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1
Ito, Shun, and Junji Konuma. "Disruptive selection of shell colour in land snails: a mark–recapture study of Euhadra peliomphala simodae." Biological Journal of the Linnean Society 129, no. 2 (2019): 323–33. http://dx.doi.org/10.1093/biolinnean/blz168.
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Abstract Many theoretical studies have suggested that disruptive selection plays an important role in phenotypic divergence, but few studies have determined the action of disruptive selection on phenotypic divergence via field studies. This study investigated the effect of disruptive selection on shell colour polymorphism in the Japanese land snail Euhadra peliomphala simodae to determine whether extreme phenotypes of snail shell colour are favoured over intermediate phenotypes. We conducted field surveys on an oceanic island with black, yellow and intermediate-coloured E. p. simodae snails. We captured and marked ~1800 individual snails and monitored their survival over 18 months. We quantified shell colours against images and examined the frequency distribution of shell colour variation. The variation exhibited a bimodal distribution with a far lower frequency of intermediate-coloured snails than of black or yellow snails. The population sizes of the three snail groups fluctuated synchronously with the changing seasons. Bayesian estimates showed lower survival rates for juvenile intermediate-coloured snails than for juvenile black and yellow snails, implying there was disruptive selection associated with shell colour. We suggest this disruptive selection may have resulted in the evolutionary divergence of the snail’s shell colour within the lineage having high shell colour variation.
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ESCH, G. W., L. A. CURTIS, and M. A. BARGER. "A perspective on the ecology of trematode communities in snails." Parasitology 123, no. 7 (2001): 57–75. http://dx.doi.org/10.1017/s0031182001007697.
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This paper presents a perspective on the ecology of trematodes in snail hosts based on recent evidence. Because flukes use snails almost obligatorily as first intermediate hosts, we highlight the role of gastropods as keystone species for trematodes and their communities. After reviewing recent developments in the transmission of trematodes to and from snails, we discuss trematode communities within individual snails (infracommunities) and in snail populations (component communities). Results garnered using various protocols at the infracommunity level are reviewed. The few data available, all from marine systems, indicate that low colonization rates characterize infracommunities, suggesting that trematode infracommunities tend to be isolationist in character rather than interactive. The variety of trematode species present in a component community seems to be determined by spatial overlap of definitive hosts. Relative abundance of species in a component community shows little dependence on negative interspecific interactions at the level of the infracommunity. Temporal aspects of trematode communities are related to the life history of the host snail. The component communities of long-lived snails (mostly marine) integrate many infection episodes whereas shorter-lived snails (mostly freshwater) acquire new component communities each time host cohorts turnover.
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Miller, Aroha A., and Robert Poulin. "Parasitism, movement, and distribution of the snail Diloma subrostrata (Trochidae) in a soft-sediment intertidal zone." Canadian Journal of Zoology 79, no. 11 (2001): 2029–35. http://dx.doi.org/10.1139/z01-167.
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Despite reports of their effects on host reproduction, growth, survival, and habitat use, the role of parasites in determining community structure is still poorly understood. Trematode infections in snails are a ubiquitous feature of intertidal systems worldwide. In this study, the influence of a trematode parasite on the movement and dispersal of the trochid snail Diloma subrostrata on a soft-sediment shore is examined using markrecapture experiments. The natural densities and shell widths of the snail peak between the upper and lower portions of the intertidal zone; marked snails were released within this area. Parasitized snails tended to have larger shells than nonparasitized conspecifics, and larger snails tended to move a greater linear distance than smaller snails in the 24 h following their marking and release. After shell width was corrected for, parasitized snails were found to move a significantly shorter distance than nonparasitized snails. In addition, the mean direction chosen by parasitized snails was almost parallel to the water's edge, whereas that taken by nonparasitized snails was almost directly toward the upper portion of the intertidal zone. Although the mean directions taken by the two types of snails were statistically different, the considerable scatter in the distributions of directions taken by individual snails casts a doubt over the biological significance of the result. Without detailed knowledge of the parasite's full life cycle it is difficult to determine whether this small bias in the direction of dispersal is an adaptive manipulation of snail behaviour by the parasitic trematode. Nevertheless, these results show that the trematode limits the range of movement, and possibly the direction of movement, of parasitized D. subrostrata, and can therefore contribute to the spatial structuring of the snail population.
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Hayashi, Masakazu, and Shinji Sugiura. "Shell-breaking predation on gastropods by Badister pictus (Coleoptera, Carabidae) with strikingly asymmetric mandibles." ZooKeys 1044 (June 16, 2021): 815–30. http://dx.doi.org/10.3897/zookeys.1044.62293.
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The adults and larvae of some groups in the coleopteran family Carabidae are known to prey on snails (Mollusca: Gastropoda). Most species of the carabid tribe Licinini are believed to feed on live snails. However, the snail-eating behavior of only a few species has been studied. Whether adults of the licinine genus Badister can prey on live snails was tested by providing 155 live snails of 20 species (eleven terrestrial and nine aquatic species) to adults of Badister pictus Bates, 1873, and observing their behavior under laboratory conditions. Six of the 20 snail species have an operculum that can close the aperture of the shell. Each B. pictus adult attacked all of the snails provided. Badister pictus successfully preyed on ten terrestrial and six aquatic snail species. These beetles used their strikingly asymmetrical mandibles to break the dextral shells along the dorsal part of the whorls from the outer lip of the aperture towards the apex, allowing subsequent consumption of the soft bodies. However, 41.9% of snails could not be eaten by B. pictus adults. The rate of predation success by B. pictus decreased with increasing shell size and thickness of snails. In addition, the presence of an operculum decreased the rate of predation success by B. pictus. The results show that the shell size, thickness, and operculum of some snail species could play important roles in preventing B. pictus mandibles from breaking the shells. Therefore, Badister beetles may exert selective pressure on the evolution of defensive shell structures in small-sized snails.
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Hurley, M., MN Hearnden, D. Blair, and BH Kay. "Larval trematodes in freshwater snails at the Ross River Reservoir, northern Australia, with emphasis on Trichobilharzia sp(p)., causative agents of swimmer's itch." Marine and Freshwater Research 45, no. 4 (1994): 563. http://dx.doi.org/10.1071/mf9940563.
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Prevalence of trematode cercariae within freshwater snails at the Ross River reservoir is presented, with special attention to Trichobilharzia sp(p). (Digenea:Schistosomatidae), known causative agents of schistosome dermatitis. Three pulmonate snails-a lymnaeid, Austropeplea lessoni, and two planorbids, Gyraulus gilberti and Amerianna carinata-and one prosobranch snail, Thiara balonnensis, were common in the reservoir. These snails were infected with trematode cercariae representing six different families. Both Austropeplea lessoni (4.5%) and G. gilberti (1.8%) act as intermediate hosts of Trichobilharzia sp(p). Trematode infection levels increased as snail size increased. The implication for surveillance techniques is that only the larger snails (A. lessoni > 10 mm, G. gilberti > 3 mm and Amerianna carinata >6 mm) require dissection to determine the prevalence of trematode infections.
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Paul, Pranesh, Koushik Paul, Rupsha Karmakar, Arnab Shee, Debaditya Kumar, and Gautam Aditya. "The exotic gastropod Clea helena (von dem Busch, 1847) as a predator of freshwater gastropods: a threat to native biota in India?" Limnological Review 21, no. 1 (2021): 55–62. http://dx.doi.org/10.2478/limre-2021-0005.
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Abstract The carnivorous snail Clea (Anentome) helena (von dem Busch, 1847) (Gastropoda: Nassariidae), commonly called as the “assassin snail” is sold worldwide including India for aesthetics and the ability to kill pest snails in aquaria. Assuming invasion as a fair possibility, the predation potential of C. helena on seven native freshwater snails was assessed. The exotic predator consumed all the native snail species provided in the experiment and prey consumption varied with the prey species identity, the prey density and the prey size class. Future colonization and establishment of C. helena in Indian freshwater ecosystems may reduce the abundance of the native gastropod snails, in absence of suitable intervention.
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Hayashi, Masakazu, and Shinji Sugiura. "Climbing rice plants above the waterline: escape of freshwater snails from underwater predation by snail-eating specialists." Biological Journal of the Linnean Society 130, no. 4 (2020): 751–55. http://dx.doi.org/10.1093/biolinnean/blaa087.
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Abstract Freshwater molluscs have physical defences such as shells to protect their inner soft bodies from underwater predators. However, some predators have specialized mouthparts that can destroy the snail’s tough and/or spiral shells. Therefore, these snails could have evolved specific defences against their specialist predators. We observed the freshwater snail Austropeplea ollula (Pulmonata: Lymnaeidae) frequently climbing rice plants above the water in paddy fields in Shimane, central Japan. We also found the beetle larvae of Hydrophilus acuminatus (Coleoptera: Hydrophilidae), which are known as snail-eating specialists, in waters of the same paddy fields. We hypothesized that A. ollula climbs rice plants above the water to escape underwater predation by H. acuminatus and that the escape behaviour of snails may be specifically triggered by chemical cues from snail-eating specialists and/or killed conspecifics. To test both these hypotheses, we conducted laboratory experiments. The results demonstrated that chemical cues (e.g. body fluids) from killed conspecifics could trigger A. ollula to crawl above the waterline. Furthermore, chemical cues (e.g. scent and digestive enzymes) from H. acuminatus could promote the behaviour. Therefore, A. ollula can successfully escape from H. acuminatus by climbing the rice plants above the water.
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Eliuk, L. K., S. Brown, R. C. Wyeth, and J. T. Detwiler. "Parasite-modified behaviour in non-trophic transmission: trematode parasitism increases the attraction between snail intermediate hosts." Canadian Journal of Zoology 98, no. 7 (2020): 417–24. http://dx.doi.org/10.1139/cjz-2019-0251.
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Many parasites with complex life cycles cause host behavioural changes that increase the likelihood of transmission to the next host. Parasite modification is often found in trophic transmission, but its influence on non-trophic transmission is unclear. In trematodes, transmission from the first to second intermediate host is non-trophic, suggesting that free-swimming larvae (cercariae) emerging in closer proximity to the next host would have higher transmission success. We performed a series of behavioural experiments with echinostome trematodes and their snail hosts to determine if potential second hosts (ramshorn snail, genus Planorbella Haldeman, 1842) were more attracted to parasitized first hosts (marsh pondsnail, Lymnaea elodes Say, 1821). In a Y maze, a responding snail (Planorbella sp.) was placed in the base and its response to five treatments was assessed: no stimulus, turion duckweed (Lemna turionifera Landolt; a food item), non-parasitized L. elodes, parasitized L. elodes, and finally parasitized versus non-parasitized L. elodes. Snails showed some attraction to uninfected snails, but had a stronger response to infected first host snails. These results indicate that potential second host snails were more attracted to parasitized, heterospecific first host snails over non-parasitized heterospecific snails. This study demonstrates that echinostome trematodes alter snail behaviour by changing navigational choices in uninfected potential hosts through a chemical communication mechanism.
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Levri, Edward P., Andrea N. Dubensky, Ashley S. Mears, and Carol A. Opiela. "Interpopulation variation in predator avoidance behavior of a freshwater snail to the same predator." Canadian Journal of Zoology 90, no. 5 (2012): 616–23. http://dx.doi.org/10.1139/z2012-027.
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The New Zealand mud snail ( Potamopyrgus antipodarum (J.E. Grey, 1843)) responds to the presence of predatory fish by moving to a safer environment. These experiments attempted to determine if predator detection by the snail results in specific responses to light and (or) gravity by the snail and if snails respond more or less to fish from their native lake compared with fish from a foreign lake. Snails and fish (Gobiomorphus cotidianus McDowall, 1975) were collected from lakes Alexandrina and Peorua from the South Island of New Zealand. Snails were placed in behavioral chambers and tested for their responses to the direction of light, vertical orientation with respect to gravity, and rate of movement in light and dark conditions. Snails from each lake were exposed to one of three treatments: plain water, water from fish from Lake Alexandrina, and water from fish from Lake Peorua. Results showed no effect of direction of light on behavior. Snails from Lake Alexandrina were not found to alter their up or down movements in response to the detection of fish. However, snails from Lake Peorua moved down more in response to fish from their own lake than fish from Lake Alexandrina or no fish. Both snail populations increase their speed in the light more when detecting Alexandrina fish compared with Peorua fish and no fish. Both snail populations show some evidence of enhanced response to local predator populations. Interestingly, different behavioral mechanisms appear to be responsible for the avoidance behaviors in each population.
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Baur, Anette, and Bruno Baur. "Are roads barriers to dispersal in the land snail Arianta arbustorum?" Canadian Journal of Zoology 68, no. 3 (1990): 613–17. http://dx.doi.org/10.1139/z90-091.
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The effect of road width on dispersal in the land snail Arianta arbustorum was examined by recording displacements of marked individuals during one activity season (3 months) in central Sweden. For two sites, a paved road (8 m wide, low traffic density) and an unpaved track (3 m wide), the snails' movements were largely confined to roadside verges. The snails followed the vegetation belts; the average displacements ranged from 1.5 to 4.9 m at different sites. Several snails covered large distances, the maximum recorded being 14 m. Despite these long-distance dispersers, only one of the recaptured snails crossed the paved road and two crossed the track, indicating that the road and, to a minor extent, the track acted as dispersal barriers. By contrast, an overgrown path (0.3 m wide) did not influence the snails' movement. Our results suggest that snail populations separated by paved roads with high traffic densities may be isolated from each other.
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Levri, Edward P. "Perceived predation risk, parasitism, and the foraging behavior of a freshwater snail (Potamopyrgus antipodarum)." Canadian Journal of Zoology 76, no. 10 (1998): 1878–84. http://dx.doi.org/10.1139/z98-122.
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Foraging behavior can be influenced by such factors as predation risk, individual size, and parasite infection. Snails (Potamopyrgus antipodarum) placed in tanks with large rocks were exposed to four types of water: (1) water with crushed snails, (2) water from a tank in which fish (Gobiomorphus cotidianus) were fed only trout chow, (3) water from a tank where the fish were also fed snails, and (4) plain water. Snails could respond by moving to the top of rocks (where algal food was present) or to the bottom of rocks (where the predation risk was lower). The snails responded to fish chemicals by moving to the bottom of rocks. The response was dependent on snail size and fish diet. Smaller snails moved to the bottom of rocks more than larger snails did. Trematode-infected snails were found on top of the rocks more than other classes of snails, but infected snails still moved to the bottom of rocks in response to the fish predator. Snails eaten by fish in the field tend to be smaller than snails in the overall available population. Thus, snails that are more vulnerable to predation respond more intensely to the odor of fish by moving to the bottom of rocks. This size-dependent response to fish appears to be independent of the occurrence of trematode infection.
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Gérard, Claudia. "Energy constraint exerted by the parasite Schistosoma mansoni on the locomotion of its snail host, Biomphalaria glabrata." Canadian Journal of Zoology 74, no. 4 (1996): 594–98. http://dx.doi.org/10.1139/z96-068.
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The consequences of the constraint caused by the parasite Schistosoma mansoni on the locomotory activity of its snail host, Biomphalaria glabrata, were studied during the patent period. Rates of locomotion were determined 6 times per 24-h period for juvenile and adult snails with single-miracidium infections, then compared with those of healthy snails of the same age. The locomotory activity of infected snails was the same during the day and at night, whereas control snails moved less at night than during the day. The locomotion of snails infected when immature was similar to that of the controls during the day and superior at night. The locomotion of snails infected when mature decreased regularly during patency and clearly decreased in comparison with that of healthy snails. The results are interpreted in terms of energy constraint on the mode of resource allocation of the host due to the parasite.
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Sutcharit, Chirasak, Phanara Thach, Samol Chhuoy, et al. "Annotated checklist of the land snail fauna from southern Cambodia (Mollusca, Gastropoda)." ZooKeys 948 (July 13, 2020): 1–46. http://dx.doi.org/10.3897/zookeys.948.51671.
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Prior to this study, few collections and records were made of the land snails in Cambodia and the historical taxa had never been reviewed. Herein a report on the land snail diversity based on specimens collected recently from karstic and non-karstic areas in southern Cambodia is provided. This checklist presents 36 species of land snails (two Neritimorpha, six Caenogastropoda, and 28 Heterobranchia). Illustrations and brief taxonomic notes/remarks are provided for every species. We also described Georrisa carinata Sutcharit & Jirapatrasilp, sp. nov. based on some distinct shell morphological characters. Since the first descriptions during the colonial period in the nineteenth century, some land snail species (e.g., Trichochloritis norodomiana, Durgella russeola, Anceyoconcha siamensis obesulacomb. nov., Anceyoconcha chaudoensiscomb. nov., and Succinea tenuis) have not been reported subsequently. This probably reflects a lack of knowledge concerning land snail biodiversity in this country. To our knowledge, this is the first comprehensive survey of land snails in southern Cambodia. A need for more field research and systematic revision of the land snails in this interesting region is also highlighted and demonstrated.
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Yanes, Yurena. "Stable isotope ecology of land snails from a high-latitude site near Fairbanks, interior Alaska, USA." Quaternary Research 83, no. 3 (2015): 588–95. http://dx.doi.org/10.1016/j.yqres.2015.03.004.
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Land snails have been investigated isotopically in tropical islands and mid-latitude continental settings, while high-latitude locales, where snails grow only during the summer, have been overlooked. This study presents the first isotopic baseline of live snails from Fairbanks, Alaska (64°51’N), a proxy calibration necessary prior to paleoenvironmental inferences using fossils. δ13C values of the shell (– 10.4 ± 0.4‰) and the body (– 25.5 ± 1.0‰) indicate that snails consumed fresh and decayed C 3-plants and fungi. A flux-balance mixing model suggests that specimens differed in metabolic rates, which may complicate paleovegetation inferences. Shell δ18O values (– 10.8 ± 0.4‰) were ~ 4‰ higher than local summer rain δ18O. If calcification occurred during summer, a flux-balance mixing model suggests that snails grew at temperatures of ~ 13°C, rainwater δ18O values of ~– 15‰ and relative humidity of ~ 93%. Results from Fairbanks were compared to shells from San Salvador (Bahamas), at 24°51’N. Average (annual) δ18O values of shells and rainwater samples from The Bahamas were both ~ 10‰ 18O-enriched with respect to seasonal (summer) Alaskan samples. At a coarse latitudinal scale, shell δ18O values overwhelmingly record the signature of the rainfall during snail active periods. While tropical snails record annual average environmental information, high-latitude specimens only trace summer season climatic data.
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Kaloyianni, Martha, and Maria Lazaridou-Dimitriadou. "Nitrogen excretion and the uricolytic enzymatic system in the nephridia and hepatopancreas of the snail Xeropicta arenosa." Canadian Journal of Zoology 67, no. 10 (1989): 2473–77. http://dx.doi.org/10.1139/z89-349.
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The quantitative and qualitative examination of the uricolytic system in the nephridia and hepatopancreas of the terrestrial snail Xeropicta arenosa showed the presence of all the metabolites of uric acid catabolism, and examination of the metabolites of the uricolytic system in the snails waste products revealed that uric acid was the main nitrogenous waste product excreted. Correlation of excretion capability with the age of the snails revealed that (i) uric acid concentration was nine times higher in the waste products of the juveniles than in those of the old snails, (ii) urea was detectable only in waste products of old snails, (iii) traces of ammonia were detected in the waste products of snails of both ages, and (iv) the amount of allantoin present in the old snails' nephridia and heart was significantly higher than in those of the juveniles. On the other hand, all snails, regardless of age, stored most uric in the nephridia. Uric acid nitrogen represented 1% of the total nitrogen in the nephridia. Data from chemical analysis were confirmed by radiochemical analysis and showed the existence of the complete sequence of uricolytic catabolites in the snails' waste products and nephridia.
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Phiri, A. M., I. K. Phiri, A. Chota, and J. Monrad. "Trematode infections in freshwater snails and cattle from the Kafue wetlands of Zambia during a period of highest cattle–water contact." Journal of Helminthology 81, no. 1 (2007): 85–92. http://dx.doi.org/10.1017/s0022149x07387786.
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AbstractA total of 984 snails, comprising nine species, were collected from six areas in the Kafue wetlands between August and October 2003 to assess larval trematode infections. Of these, 135 (13.7%) were positive. Most trematode infections were recorded from Lymnaea natalensis (42.8%), which harboured four of the five morphologically different cercariae found. No trematodes were recovered from Bellamya capillata, Biomphalaria pfeifferi, Melanoides tuberculata, Physa acuta and Cleopatra nswendweensis. One snail (0.2%) of 416 Bulinus snails shed brevifurcate-apharyngeate distome cercariae while three (0.7%) shed amphistomes. Gymnocephalous and longifurcate-pharyngeate distome were the commonest types of cercariae recorded while xiphidiocercaria was the least common. The highest prevalence rates of F. gigantica (68.8%) and amphistomes (50.0%) in cattle (n = 101) were in Chiyasa while those in Kaleya had the lowest (9.1 and 18.2%, respectively). In most habitats, infections were recorded in both cattle and snails. Critical determinants of infection may have been the distance of settlements and/or cattle kraals, the number of animals in nearby homesteads and the presence of susceptible host snails. This study suggests that fascioliasis and amphistomiasis could be major constraints of cattle production in the Kafue wetlands because favourable factors were available to introduce and maintain the infections. It further provides a starting point for some comprehensive studies on snail-related aspects of transmission and snail host ecology in Zambia.
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Withers, Philip, Scott Pedler, and Michael Guppy. "Physiological Adjustments during Aestivation by the Australian Land Snail Rhagada tescorum (Mollusca : Pulmonata : Camaenidae)." Australian Journal of Zoology 45, no. 6 (1997): 599. http://dx.doi.org/10.1071/zo97009.
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Specimens of the camaenid snail Rhagada tescorum were collected from Barrow Island, Western Australia, where they typically aestivate underground during the long dry season and emerge after heavy rainfall. Aestivation is associated with a profound decrease in metabolic rate (from 50 to 5 µL g-1 h-1 ) and evaporative water loss (from 11 to 0.3 mg g-1 h-1). Even after approximately 10–12 months of aestivation in the laboratory, aestivating snails had only a slightly lower body-water content (82.1% of shell-free mass) than rehydrated individuals (84.5%), but a significantly higher haemolymph sodium concentration (94 cf. 55 mM) and osmotic concentration (233 cf. 134 mOsm); the difference in haemolymph potassium concentration (3.7 cf. 2.6 mM) was not significant. The haemolymph pO2 was lower for aestivating snails (6.25 kPa) than awake snails (10.8 kPa) but there was no hypercapnia (pCO2 = 1.4 cf. 1.3 kPa) or acidosis (pH = 7.64 cf. 7.62) in aestivating snails. These physiological adjustments of Rhagada tescorum during aestivation are similar to those of other arid-zone land snails, except for the absence of hypercapnia and acidosis, and indicate that this snail is well adapted to withstand the metabolic and hygric demands of extended periods of drought.
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Nowakowska, Anna, Grażyna Świderska-Kołacz, Justyna Rogalska, and Michał Caputa. "Effect of winter torpor upon antioxidative defence in Helix pomatia." Canadian Journal of Zoology 87, no. 6 (2009): 471–79. http://dx.doi.org/10.1139/z09-025.
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Arousal of land snails from torpor is inseparably connected with an increase in oxygen consumption leading to oxidative stress. Therefore, activity of antioxidant defence system (antioxidant enzymes and reduced glutathione) and degree of oxidative damage (concentration of malondialdehyde as an index of lipid peroxidation) in the snail Helix pomatia L., 1758 were tested to check whether torpid snails are able to activate their antioxidative defence against oxidative damage prior to arousal from winter torpor. Snails, which were collected from their natural habitats, were tested at the beginning, in the middle part, and at the end of winter torpor. Active snails collected in autumn and spring were taken as control groups. Snails were immediately killed and their foot, hepatopancreas, and kidney were used for the biochemical assays. Winter torpor induced significant changes in activities of the crucial antioxidant substances. The lowest activities were observed at the beginning of torpor, whereas activity of some of these enzymes was significantly enhanced prior to spring arousal. Reduced glutathione concentration did not show time-dependent changes during winter torpor. MDA (1,3-propanedial) level was elevated in the kidney and foot but was unchanged in the hepatopancreas. In conclusion, the snail H. pomatia is able to maintain REDOX balance necessary to prevent oxidative injury during arousal.
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Kupfernagel, Sandra, and Bruno Baur. "Sperm utilization in subadult and adult simultaneous hermaphrodite snails mating in the wild." Canadian Journal of Zoology 89, no. 11 (2011): 1041–49. http://dx.doi.org/10.1139/z11-080.
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In species with multiple mating and long-term sperm storage, males are expected to show a preference for mating with virgin and young females to reduce the risk of sperm competition. In various simultaneous hermaphrodite land snail species, sperm production precedes egg production by 2–4 weeks, resulting in a short period of protandric hermaphroditism before shell growth is completed. In a natural population, we collected copulating pairs of the simultaneous hermaphrodite land snail Arianta arbustorum (L., 1758) consisting either of two adults, of two subadults, or of one adult and one subadult snail, and determined the paternity of their hatchlings that emerged from subsequently deposited eggs. Adult snails used sperm received from subadult mating partners for egg fertilization in the same frequency as sperm from adults, indicating that subadult and adult snails do not differ in male function. Furthermore, an unfinished shell is not a reliable indicator for virginity, because 35% of the subadult individuals had already sperm stored from previous mating(s). Compared with adults, young individuals exhibited a lower risk of sperm competition, indicated by a higher last mate sperm precedence. However, subadult snails produced fewer eggs than adult snails, counteracting the evolutionary advantage of preferring a young partner with low sperm competition risk.
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Khan, Hamid R., Mary Lou Ashton, Spencer T. Mukai, and A. S. M. Saleuddin. "The effects of mating on the fine structure of neurosecretory caudodorsal cells in Helisoma duryi (Mollusca)." Canadian Journal of Zoology 68, no. 6 (1990): 1233–40. http://dx.doi.org/10.1139/z90-184.
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The hermaphroditic snail Helisoma duryi does not lay eggs if raised as a virgin in isolation or when castrated. The fine structure of its neurosecretory caudodorsal cells (CDC), which produce the putative egg-laying hormone, was studied in reproductively inactive virgin and castrated snails and compared with that of the reproductively active mated snails, using electron microscopy, tannic acid incubation technique, and electron microscope autoradiography after injection of [3H]leucine. The CDC of virgin and castrated snails accumulate large numbers of elementary granules and appear synthetically inactive, whereas the CDC of mated snails contain fewer elementary granules and possess features characteristic of increased protein synthesis. The flattened cisternae of the rough endoplasmic reticulum of the CDC of the virgins become swollen 3 h after first mating. In tannic acid incubated tissues, more released granules were seen in CDC from snails 12 h after first mating than in CDC from virgin and castrated snails. Autoradiography showed more silver grains on the CDC from snails 12–48 h after first mating than on those from snails 3–6 h after first mating. It is suggested that, in Helisoma, mating provides a stimulus to the CDC for increased protein synthesis and release of the putative egg-laying hormone.
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Mažuran, Neda, and Goran Kovačević. "Growth and Reproduction of Planorbarius corneus (Linnaeus, 1758) in Laboratory Conditions." Croatian Journal of Fisheries 79, no. 3 (2021): 111–18. http://dx.doi.org/10.2478/cjf-2021-0012.
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Abstract This study presents the results of observation on growth and reproduction of Planorbarius corneus (Linnaeus, 1758) (Gastropoda, Pulmonata) over the course of several years of continuous rearing in the laboratory in order to use them as test organisms for toxicity testing of chemicals. Some growth and reproduction features (shell diameter increase, fecundity, hatching time and rate, age at first reproduction, juvenile survival), which could provide more information for culturing P. corneus in the laboratory, are presented. The quantitative results of growth and reproduction in laboratory conditions were obtained: heterogenous growth varied between 0.1 mm and 5.3 mm in individual snails, production of 0.6 egg masses per snail/day and 11 eggs per snail/day. A statistically significant negative correlation between initial snail size and growth was noticed. In the second part of the experiment, the reproductive output of 4 isolated snails was compared to that of permanently grouped snails. As a result, 2-fold decreased growth and 4-fold decreased reproductive output in the progeny of isolated animals was noticed.
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McKenzie, V. J., W. E. Hall, and R. P. Guralnick. "New Zealand mudsnails (Potamopyrgus antipodarum) in Boulder Creek, Colorado: environmental factors associated with fecundity of a parthenogenic invader." Canadian Journal of Zoology 91, no. 1 (2013): 30–36. http://dx.doi.org/10.1139/cjz-2012-0183.
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New Zealand mudsnails (Potamopyrgus antipodarum (Gray, 1853)) are non-native snails that are increasingly spreading in freshwater systems in North America. Most invasive populations are parthenogenic and threaten native freshwater diversity. We observed variability of P. antipodarum fecundity each month for 16 months at a recently invaded site in Boulder Creek, Colorado. We collected 100 snails each month and dissected them to count embryos in the brood sac. We used a general linear model analysis to examine water-quality variables as predictors of the monthly variability in P. antipodarum fecundity. After dissecting 1600 snails, we observed four male individuals (<1%), brood sizes ranging from 0 to 70 embryos per snail, reproductively mature females at 3.2 mm in length or greater, and a significant relationship between snail length and embryo counts (r2 = 0.38, p < 0.001). The model with the highest level of support for predicting variability in snail fecundity included water temperature, snail shell length, water hardness (calcium carbonate), and nutrient levels (total phosphate) (adjusted r2 = 0.53, p < 0.01). These variables may be important for snail growth and promote increased rates of reproduction in this parthenogenic, invasive snail. These results can further inform efforts to model geographic areas at high risk of P. antipodarum establishment and rapid demographic growth.
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Peraud, Olivier, Jason S. Biggs, Ronald W. Hughen, et al. "Microhabitats within Venomous Cone Snails Contain Diverse Actinobacteria." Applied and Environmental Microbiology 75, no. 21 (2009): 6820–26. http://dx.doi.org/10.1128/aem.01238-09.
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ABSTRACT Actinomycetes can be symbionts in diverse organisms, including both plants and animals. Some actinomycetes benefit their host by producing small molecule secondary metabolites; the resulting symbioses are often developmentally complex. Actinomycetes associated with three cone snails were studied. Cone snails are venomous tropical marine gastropods which have been extensively examined because of their production of peptide-based neurological toxins, but no microbiological studies have been reported on these organisms. A microhabitat approach was used in which dissected tissue from each snail was treated as an individual sample in order to explore bacteria in the tissues separately. Our results revealed a diverse, novel, and highly culturable cone snail-associated actinomycete community, with some isolates showing promising bioactivity in a neurological assay. This suggests that cone snails may represent an underexplored reservoir of novel actinomycetes of potential interest for drug discovery.
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Shaw, Ross. "Host tracking and photosensitivity in Chaetogaster limnaei limnaei (Oligochaeta)." Canadian Journal of Zoology 70, no. 3 (1992): 578–81. http://dx.doi.org/10.1139/z92-086.
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Chaetogaster limnaei limnaei were separated from host snails (Physa skinneri) for increasing periods of time. The oligochaetes responded to a snail's slime trail by increased activity and distance moved along the slime trail. These responses increased with increasing periods of separation from the snail. When exposed to a directional light source, C. l. limnaei displayed an initial positive phototactic response. Movement towards light from the same direction decreased significantly in a second 4-h period, but movement towards light from a different direction was equivalent to the initial response, suggesting the response was an initial one to a change in light.
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Gao, Jian, Cheng Yang, Zehui Zhang, Zhengwen Liu, and Erik Jeppesen. "Effects of co-occurrence of invading Procambarus clarkii and Pomacea canaliculata on Vallisneria denseserrulata-dominated clear-water ecosystems: a mesocosm approach." Knowledge & Management of Aquatic Ecosystems, no. 422 (2021): 29. http://dx.doi.org/10.1051/kmae/2021029.
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Single invaders often substantially alter ecosystems, but the potential impacts by multiple invaders remain understudied. The golden apple snail (Pomacea canaliculata) and the red swamp crayfish (Procambarus clarkii) are two widespread coinvaders. To test the effects of co-occurrence of the two species on a clear-water macrophyte state, we performed a 20-day experiment in 16 mesocosms (4 contained only two snails, 4 contained only two crayfishes, 4 contained two snails and two crayfishes, and 4 controls). Comparing with the control, the leaf length, number, and biomass of Vallisneria denseserrulata had decreased in the snail-only and crayfish-only treatments. In the crayfish-only treatment, total nitrogen, total phosphorus and total suspended solids had increased compared with the control, while they did not differ between the snail-only and the control treatment. Nutrients and turbidity concentrations did not differ between the snail + crayfish and the crayfish-only treatment, and plant biomass did not differ between the snail + crayfish and the snail-only treatment. These findings suggest that golden apple snails mainly affected the lake ecosystem by plant grazing, while red swamp crayfishes disturbed the sediment by increasing nutrients in the water and through resuspension. These snail and crayfish together had mainly additive effects on macrophyte and the physico-chemical variables studied.
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Baker, GH. "The Dispersal of Cernuella-Virgata (Mollusca, Helicidae)." Australian Journal of Zoology 36, no. 5 (1988): 513. http://dx.doi.org/10.1071/zo9880513.
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The dispersal of the land snail Cernuella virgata was measured in South Australia by mark-release- recapture. Dispersal was not influenced by the paint used for marking, displacement of the snails during the marking process or crowding at release points. Snails moved out of a well-grazed permanent pasture to adjacent weedy roadside vegetation in early summer. They returned to the pasture in autumn. Factors which might direct this movement are discussed. Average movements varied between 0.1 and 0.4 m day-'. Some snails moved more than 25 m in one month in spring-summer and 50 m in 3 months in autumn-winter.
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GAUSLAA, Y., H. HOLIEN, M. OHLSON, and T. SOLHØY. "Does snail grazing affect growth of the old forest lichen Lobaria pulmonaria?" Lichenologist 38, no. 6 (2006): 587–93. http://dx.doi.org/10.1017/s0024282906006025.
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Grazing marks from snails are frequently observed in populations of the old forest epiphyte Lobaria pulmonaria. However, grazing marks are more numerous in thalli from deciduous broadleaved forests than in thalli from boreal Picea abies forests, due to higher populations of lichen-feeding molluscs in deciduous stands. Here we tested for deleterious effects of snails on the lichens by transplanting 600 more or less grazed L. pulmonaria thalli from deciduous forests to snail-free P. abies forests. Subsequent measurements showed that growth rates were as high in thalli with many grazing marks as those without, suggesting that growth of mature lobes of L. pulmonaria are not inhibited by the recorded grazing pressure imposed by lichen feeding snails.
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Lailiyah, Shofiyatul, Diana Arfiati, Asus Maizar Suryanto Hertika, Neni Diah Kusumaning Arum, and Catur Budi Noviya. "The Effectiveness of Filopaludina javanica and Sulcospira testudinaria in Reducing Organic Matter in Catfish (Clarias sp.) Aquaculture Wastewater." Jurnal Ilmiah Perikanan dan Kelautan 13, no. 1 (2021): 106. http://dx.doi.org/10.20473/jipk.v13i1.23085.
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HighlightCatfish aquaculture wastewater contains organic matter that exceeds the quality standard of 68.75 mg / L and 72.48 mg / L.Tutut Jawa snail (F. javanica) can reduce organic matter in waste by up to 92%.Susuh Kura snail (S. testudinaria) can reduce organic matter in waste by up to 87%.Catfish aquaculture wastewater treatment with snails only takes 8 hours. Abstract The residual or wastewater from the cultivation process that is discharged directly into common waters can reduce the quality of the waters because it contains a lot of organic material from organism feces and feed residue, so it needs management first. The purpose of this study was to determine the ability of Javanese snails and freshwater gastropods to reduce total organic matter in catfish culture waste. The research method used was the experiment with 2 factor Factorial completely randomized design, namely the measurement time (4, 8, 12, and 16 hours) and the abundance of the Tutut Java snail and freshwater gastropods (100%, 75%, 50%, 25%, and control) with 5 repetitions. Tutut Java snails were taken from the pond at UPR Sumbermina Dau and brought to the laboratory. The results obtained in the treatment with the addition of Tutut Java snail, the total organic matter content decreased at 75% snail density by 90% (from 68.75 mg / L to 5.31 mg / L) at the 12th hour. The treatment with the addition of Freshwater Gastropods at a density of 25%, the total organic matter content decreased by 87% (from 72.48 to 9.35 mg / L) at the 8th hour. Water quality during the study was in a condition that could tolerate the Tutut Java snails and freshwater gastropods. The conclusion is that the addition of Tutut Java snail and / or freshwater gastropods can reduce the total organic matter content to the water quality standard.
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Baur, Bruno. "Effects of early feeding experience and age on the cannibalistic propensity of the land snail Arianta arbustorum." Canadian Journal of Zoology 65, no. 12 (1987): 3068–70. http://dx.doi.org/10.1139/z87-465.
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The influence of early feeding experience on egg cannibalism was examined in hatchlings of the land snail Arianta arbustorum. The propensity for cannibalism was not affected by cannibalistic or by vegetarian early feeding experience. It was, however, negatively correlated with the age of the snails. Freshly hatched snails with no prior feeding experience chose eggs exclusively, while 16-day-old snails preferred vegetable food. Furthermore, the cannibalistic propensity varied between offspring from different clutches. Restriction of the cannibalistic propensity to the hatchling stage, its nonmodifiability, and differences in its extent between clutches suggest that egg cannibalism in A. arbustorum is a genetically determined trait.
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Barrientos, Zaidett. "Sistema reproductivo, comportamiento de apareamiento y ecología básica de un caracol tropical extremadamente raro: Drymaeus tripictus (Stylommatophora: Bulimulidae)." Revista de Biología Tropical 64, no. 1 (2016): 55. http://dx.doi.org/10.15517/rbt.v64i1.18582.
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Very little is known about the ecology and biology of Drymaeus tripictus, an extremely rare and endemic land snail species from Costa Rican highlands. I studied the ecology and reproductive biology of D. tripictus from April 2009 through June 2010 in an old forest, a young forest and a Cupressus lusitanica plantation in central Costa Rica. Every three months I visited each habitat and collected specimens in 20 random sampling plots (3x3 m2 each). I observed the snail’s activity and microhabitat preference in the field, and in the laboratory I recorded high definition videos of its mating behavior and analyzed reproductive morphology with light microscopy. The snail is more abundant in the old forest (0.017 ind./m2) and prefers leaves with little epiphyllous cover (0-25 % cover, chi-square test, p <0.0001). During the dry season the snails become active between 20:00 pm and 8:00 am (chi-square = 22.65, df=3, p < 0.0001); they are inactive mainly during the afternoon (11:00 am to 16:59 pm). I found active individuals mostly on the upper side of leaves, where they feed (Chi-square =6.76, df=1, p = 0.0093). Mating is unilateral, by shell mounting, with cryptic phallus intromission and without role switching or multiple mating. Its reproductive system is morphologically similar to that of Drymaeus costaricensis. Mating behavior is as expected for snails with high-spired shells, except for the lack of role switching. The density of D. tripictus is low even when compared with other endangered bulimulids.
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Rosemond, Amy D., Patrick J. Mulholland, and Susan H. Brawley. "Seasonally shifting limitation of stream periphyton: response of algal populations and assemblage biomass and productivity to variation in light, nutrients, and herbivores." Canadian Journal of Fisheries and Aquatic Sciences 57, no. 1 (2000): 66–75. http://dx.doi.org/10.1139/f99-181.
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We determined whether there were seasonal changes in the relative importance of consumers and resources in controlling stream periphyton. Our analysis included effects on algal populations and assemblage biomass and productivity. We used factorial experiments in which we manipulated snail densities, irradiance, and streamwater nutrient concentrations during two seasons, fall and spring, and compared responses with previously published summer findings. Periphyton biomass and productivity were much greater when snails were removed and nutrients and light were elevated during all seasons, indicating that all three factors were limiting or nearly limiting throughout the year. However, the relative importance of factors shifted seasonally. Irradiance limited periphyton biomass in summer and fall but not spring. In contrast, nutrients were more limiting in seasons in which light levels were higher: nutrient addition generally resulted in effects of greater magnitude in fall and spring than in summer. Snail growth was stimulated by enhanced irradiance in summer (p = 0.06) and by nutrient addition in fall, indicating resource limitation of both periphyton and snails. However, top-down control of periphyton by snails was also important: snails maintained low biomass assemblages dominated by only a few grazer-resistant species (e.g, basal cells of Stigeoclonium tenue, Chamaesiphon investiens) during all seasons.
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Chen, Xiaofeng, and Bruno Baur. "The effect of multiple mating on female reproductive success in the simultaneously hermaphroditic land snail Arianta arbustorum." Canadian Journal of Zoology 71, no. 12 (1993): 2431–36. http://dx.doi.org/10.1139/z93-339.
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The simultaneously hermaphroditic land snail Arianta arbustorum mates several times in the course of a reproductive season. Repeated matings might be adaptive for the male function of A. arbustorum to inseminate several "females." We designed an experiment to evaluate the effects of repeated mating on the female reproductive success of this hermaphrodite. Reproductive traits and survival were examined over 2 years in individuals that copulated several times per year (snails were kept in pairs), in individuals that copulated twice (once at the beginning of each year) or once (at the beginning of the first year only), and in individuals prevented from copulating (they were kept isolated). Copulations were not always reciprocally successful: 3 of 57 snails (5.3%) failed to produce fertile eggs, although their mates reproduced successfully. Similarly, 2 of 15 pairs (13.3%) failed to reproduce successfully. Snails allowed to mate repeatedly within each season tended to lay more eggs than snails that mated once per year. However, the numbers of hatchlings did not differ significantly between the two treatment groups, because eggs laid by snails allowed to mate repeatedly had a lower hatching success. Snails that remated in the second year laid more eggs that had higher hatching success, and thus produced more hatchlings than snails that mated once at the beginning of the first year only. Snails that were prevented from mating produced a few hatchlings (by self-fertilization) in the second year; their reproductive success was less than 1% of that of mated snails. Our results suggest that multiple mating is also adaptive for the female function of A. arbustorum by increasing female fecundity and fertility and serving as a hedge against unsuccessful copulations.
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Akan, Madina, Florian Michling, Katrin Matti, Sinje Krause, Judith Muno-Bender, and Jürgen Wendland. "Snails as Taxis for a Large Yeast Biodiversity." Fermentation 6, no. 3 (2020): 90. http://dx.doi.org/10.3390/fermentation6030090.
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Yeasts are unicellular fungi that harbour a large biodiversity of thousands of species, of which particularly ascomycetous yeasts are instrumental to human food and beverage production. There is already a large body of evidence showing that insects play an important role for yeast ecology, for their dispersal to new habitats and for breeding and overwintering opportunities. Here, we sought to investigate a potential role of the terrestrial snails Cepaea hortensis and C. nemoralis, which in Europe are often found in association with human settlements and gardens, in yeast ecology. Surprisingly, even in a relatively limited culture-dependent sampling size of over 150 isolates, we found a variety of yeast genera, including species frequently isolated from grape must such as Hanseniaspora, Metschnikowia, Meyerozyma and Pichia in snail excrements. We typed the isolates using standard ITS-PCR-sequencing, sequenced the genomes of three non-conventional yeasts H. uvarum, Meyerozyma guilliermondii and P. kudriavzevii and characterized the fermentation performance of these three strains in grape must highlighting their potential to contribute to novel beverage fermentations. Aggravatingly, however, we also retrieved several human fungal pathogen isolates from snail excrements belonging to the Candida clade, namely Ca. glabrata and Ca. lusitaniae. Overall, our results indicate that diverse yeasts can utilise snails as taxis for dispersal. This courier service may be largely non-selective and thus depend on the diet available to the snails.
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Lockyer, Anne E., Catherine S. Jones, Leslie R. Noble, and David Rollinson. "Trematodes and snails: an intimate association." Canadian Journal of Zoology 82, no. 2 (2004): 251–69. http://dx.doi.org/10.1139/z03-215.
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Trematode parasites share an intimate relationship with their gastropod intermediate hosts, which act as the vehicle for their development and transmission. They represent an enormous economic and medical burden in developing countries, stimulating much study of snail–trematode interactions. Laboratory-maintained snail–trematode systems and in vitro cell cultures are being used to investigate the molecular dialogue between host and parasite. These dynamic and finely balanced antagonistic relationships, in which parasites strongly influence the physiology of the host, are highly specific and may occasionally demonstrate co-speciation. We consider the mechanisms and responses deployed by trematodes and snails that result in compatibility or rejection of the parasite, and the macroevolutionary implications that they may effect. Although for gastropods the fossil record gives some insight into evolutionary history, elucidation of trematode evolution must rely largely upon molecular approaches, and for both, such techniques have provided fresh and often surprising evidence of their origins and dispersal over time. Co-evolution of snails and trematodes is becoming increasingly apparent at both cellular and population levels; the implications of which are only beginning to be understood for disease control. Untangling the complex interactions of trematodes and snails promise fresh opportunities for intervention to relieve the burden of parasitic disease.
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Yamazaki, Daishi, Tomoki Aota, and Satoshi Chiba. "The genetic structure of the marine flatworm Stylochoplana pusilla (Rhabditophora: Polycladida) and its use of intertidal snails." Journal of the Marine Biological Association of the United Kingdom 100, no. 5 (2020): 713–17. http://dx.doi.org/10.1017/s0025315420000570.
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AbstractAlthough marine phylogeographers have accumulated knowledge of the evolutionary history of various invertebrates, there is a large bias among the taxa regarding genetic data. The order Polycladida is a typical example for which little genetic information at population level is available. Here, we focused on the polyclad flatworm Stylochoplana pusilla, distributed in the Japanese Pacific coastal area. Stylochoplana pusilla is known to have commensal relationships with certain intertidal snails, using snails (mainly Monodonta confusa) as a refugee house. During low tide, S. pusilla hides in the mantle cavity of snails to protect themselves from desiccation and predation. Here, we investigated the genetic structure of S. pusilla using a mitochondrial Cytochrome Oxidase I marker and the species diversity of snails used by it. We found that S. pusilla has high genetic diversity of its populations. While S. pusilla showed a significant genetic differentiation among populations, it was relatively low. In addition, we also showed that S. pusilla used several intertidal snail species which inhabit various coastal environments. The present study suggests S. pusilla has sufficient dispersal ability to connect among its local populations. Also, the range of available snails for S. pusilla may help the connectivity among local populations. We provide important knowledge about this invertebrate taxon with a unique ecology, which has been insufficiently studied.
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Lau, Danny C. P., Kenneth M. Y. Leung, and David Dudgeon. "Experimental dietary manipulations and concurrent use of assimilation-based analyses for elucidation of consumer - resource relationships in tropical streams." Marine and Freshwater Research 59, no. 11 (2008): 963. http://dx.doi.org/10.1071/mf07213.
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The relative contribution of autochthonous foods to consumer biomass in small tropical streams is unknown, but extrapolation of findings from temperate forest streams, where food webs are based on allochthonous resources, might be misleading. Experimental dietary manipulations were conducted to investigate the food used by the snail Brotia hainanensis (Pachychilidae), a generalist primary consumer common in Hong Kong streams, through the concurrent use of stoichiometry, stable isotope analysis (SIA) and fatty acid (FA) profiling. Juvenile B. hainanensis collected from the field were cultured under laboratory conditions and fed with conditioned leaf litter, periphyton or commercial fish-food flakes for 6 months and then compared with field-collected snails at the end of the trial. The results of the SIA and FA profiling showed that snails depended primarily on algal food. Prolonged feeding with leaf litter put B. hainanensis under elemental constraints and litter-fed snails deviated from strict stoichiometric homeostasis. Periphyton-fed, flake-fed and field-collected snails contained more total lipids and autochthonous FA biomarkers than litter-fed snails. The concurrent application of assimilation-based analyses allowed effective and accurate elucidation of consumer–resource relationships and, in the present study, confirmed the importance of autochthonous energy in a tropical stream food web. This approach will be useful for investigating complex trophic interactions.
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Chase, R., E. Darbyson, K. E. Horn, and E. Samarova. "A mechanism aiding simultaneously reciprocal mating in snails." Canadian Journal of Zoology 88, no. 1 (2010): 99–107. http://dx.doi.org/10.1139/z09-121.
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The majority of hermaphroditic animals mate on a given occasion as either male or female, but terrestrial snails and slugs generally mate reciprocally with each partner participating in both sexual roles. This manner of mating requires that the genitalia be exactly opposed prior to copulation attempts, a task made difficult in snails and slugs by the absence of hearing and very limited vision. In the brown garden snail, Cornu aspersum (Müller, 1774), we found that a small protruding structure associated with the genital atrium plays an important role in positioning the snails prior to copulation. Lesions of the penial lobe reduced mating success rates, delayed mating, increased the number of attempted intromissions, and increased the number of unilateral intromissions. The sensory capacity of the penial lobe is demonstrated by histological and electrophysiological evidence, and behavioral data suggest that the lobe is also a stimulus for the partner snail. A literature review suggests that structures functionally equivalent to the penial lobe may be present in many gastropod molluscs that mate simultaneously and reciprocally, but in none that mate in other ways.
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Hill, Walter R., Harry L. Boston, and Alan D. Steinman. "Grazers and Nutrients Simultaneously Limit Lotic Primary Productivity." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 3 (1992): 504–12. http://dx.doi.org/10.1139/f92-059.
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Nitrate and phosphate were added to two of four flow through channels in a second-order stream in eastern Tennessee to raise nutrient concentrations to 3–4 times background, while two of four sets of colonized ceramic tiles in each channel were raised above the substratum to exclude grazing snails (Elimia clavaeformis). Snail grazing maintained a thin layer of periphyton dominated by Stigeoclonium basal cells, regardless of nutrient regime. Although nutrient effects on periphyton ash-free dry mass were statistically insignificant, nutrient additions significantly increased chlorophyll a, especially where snails were excluded. Snail densities were 89% higher in nutrient-enriched channels. Photosynthesis–irradiance data suggested that nutrient enrichment increased self-shading in the periphyton. Areal-specific productivity was simultaneously limited by grazing and low nutrient concentrations: snail exclusion and nutrient enrichment both increased productivity > 2 times. The negative effect of snails on areal-specific productivity was due to (1) reduction in biomass by cropping and (2) depression of chlorophyll-specific productivity. The means by which Elimia depresses chlorophyll-specific productivity is unclear, but the depression is clearly disadvantageous to food-limited grazers. Because Elimia was the dominant invertebrate, our results indicate that low nutrient concentrations limit secondary as well as primary production in autumn.
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Schmera, Dénes, Anette Baur, and Bruno Baur. "Size-dependent shell growth and survival in natural populations of the rock-dwelling land snail Chondrina clienta." Canadian Journal of Zoology 93, no. 5 (2015): 403–10. http://dx.doi.org/10.1139/cjz-2014-0307.
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Rock-dwelling land snails, feeding on algae and lichens that grow on stone surfaces, may influence the structure and function of these ecosystems. Yet, little is known about the life history of rock-dwelling snails. We performed a 30-month mark–release–resight study in four populations of Chondrina clienta (Westerlund, 1883) inhabiting vertical walls of abandoned limestone quarries on the Baltic island of Öland, Sweden, to assess growth rate and survival of juvenile snails and determine age at maturity. We marked 800 individuals ranging in shell height from 1.4 to 4.9 mm, released them in their original habitat, and remeasured their shell height at intervals of 6 months. Shell growth of juvenile C. clienta was affected by the site (quarry wall) and the size of the individual, being highest in medium-sized snails. Shell growth occurred during both summer and winter. Annual apparent survival rates of C. clienta were size-dependent and ranged from 58.6% to 96.3%. Sexual maturity was reached at an age of 5 years, which is later than in most large snail species. Our study extends current knowledge on life history of land snails to a rarely studied group dwelling on rock surfaces.
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Devereaux, Jacqueline S. L., and Allie Mokany. "Visual and chemical cues from aquatic snails reduce chironomid oviposition." Australian Journal of Zoology 54, no. 2 (2006): 79. http://dx.doi.org/10.1071/zo05069.
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Chironomus oppositus sensu lato and the freshwater gastropod Physa acuta are distantly related taxa inhabiting temporary ponds. Although their distributions overlap, their peak abundances do not coincide in time and space. This study used field-based mesocosm experiments to examine the effect of P. acuta on the distribution and abundance of C. oppositus. Results indicated that chironomid larval abundance was substantially higher in mesocosms without P. acuta. The abundance of C. oppositus decreased as snail density increased, from one snail per litre. To investigate whether this result was due to differential survival by chironomid larvae or preferential oviposition by chironomid adults, both factors were manipulated separately and the mechanisms involved investigated. Direct-interaction experiments demonstrated that direct (mechanical) and indirect (water-borne) interference by snails had limited impact on the survivorship of third- or fourth-instar C. oppositus. Oviposition trials indicated that chironomid egg strings were five times less abundant in mesocosms containing both visual and water-borne snail cues. However, the presence of each of these cues separately did not result in a similar reduction. This study demonstrates that negative covariance occurred between larval chironomids and snails, with chironomids avoiding snails through oviposition site selection. This has important implications for understanding the mechanisms structuring freshwater communities.
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HERTEL, J., B. HABERL, J. HAMBURGER, and W. HAAS. "Description of a tandem repeated DNA sequence of Echinostoma caproni and methods for its detection in snail and plankton samples." Parasitology 126, no. 5 (2003): 443–49. http://dx.doi.org/10.1017/s0031182003003093.
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Echinostome larval stages in the snail have a great potential as effective competitors for the control of schistosomes and adult worms can cause painful intestinal diseases in humans. Ecology and transmission of the larval stages of trematodes are poorly understood, especially because their identification in field-collected samples by microscopy is difficult. We cloned, sequenced and analysed a 192 bp tandem repreated DNA sequence of Echinostoma caproni (EcSau3A), an often discussed antagonist of Schistosoma mansoni in Biomphalaria snails. PCR primers against this sequence can detect less than 10 fg of E. caproni DNA, 2 miracidia in snails 1 day p.i., 1 metacercaria in 50 mg snail tissue and 1 cercaria in 50 mg plankton with high specificity. Methods described in this study can support the discovery of fundamental ecological principles on distribution, host specificity and epidemiology of E. caproni larvae under field conditions.
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Kreps, Timothy A., Ashley K. Baldridge, and David M. Lodge. "The impact of an invasive predator (Orconectes rusticus) on freshwater snail communities: insights on habitat-specific effects from a multilake long-term study." Canadian Journal of Fisheries and Aquatic Sciences 69, no. 7 (2012): 1164–73. http://dx.doi.org/10.1139/f2012-052.
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Most studies of the impacts of invasive species are done at small spatial and short temporal scales, greatly limiting generalizations to natural ecosystems. In contrast, we examined the long-term, whole-lake impacts of predation by the introduced rusty crayfish ( Orconectes rusticus ) on snail communities in 10 lakes in northern Wisconsin, USA. In 1987 and 2002, crayfish and snails were surveyed in lakes that initially differed in O. rusticus abundance; during the 15 years between surveys, crayfish abundance changed substantially in four lakes. In the two lakes where O. rusticus populations increased from low to high densities, large reductions occurred in snail abundance. As predicted, snails declined much more in habitats preferred by O. rusticus (sand and cobble) than in habitats that are avoided by the crayfish (muck). In the two lakes where O. rusticus abundance decreased dramatically after 1987, no significant increase occurred in snail densities, illustrating the difference in response time of snail populations to release from predation relative to increasing predation. Contrary to prediction, no consistent difference in snail species composition existed between high and low crayfish density lakes.
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ARAVIND, NEELAVAR ANANTHRAM, RAJASHEKHAR KHANAGOWDA PATIL, and NEELAVAR ANANTHRAM MADHYASTHA. "Micromolluscs of the Western Ghats, India: Diversity, distribution and threats." Zoosymposia 1 (July 25, 2008): 281–94. http://dx.doi.org/10.11646/zoosymposia.1.1.17.
Full textAbstract:
The Western Ghats, India, is one of the 34 hotspots of biological diversity in India and harbour high levels of endemism in a variety of taxa. Research on the faunistic diversity of this hotspot have focused on higher taxa such as mammals and birds and lesser taxa such as land snails have not been studied. Given the rapid land transformation occurring in the Western Ghats, there is an urgent need to study the impact of land use change on poorly known taxa such as land snails. The fi rst attempt was made here to assess the distribution patterns of the land snails of the Western Ghats in relation to land use and habitat disturbances. We assessed geographical distribution patterns of microgastropods along the Western Ghats on the basis of published literature and data from fi eld studies and the impact of land use change and habitat disturbance on microgastropods in the wet forests of the central Western Ghats: a) approximately 40% of the total 269 species of land snails recorded from the Western Ghats were microgastropods, b) the southern Western Ghats harbours high species richness for both micromolluscs as well as macromolluscs compared to the central and northern Western Ghats, c) micromolluscs occur in very high densities compared to macrospecies and d) land use changes and habitat disturbances has led to 10% increase in macrogastropods over microgastropods. The present study clearly shows that land transformation and disturbance has had a severe impact on land snail diversity. Little effort is currently made in India to include lesser known taxa such as land snails in conservation programmes. This is mainly due to our lack of knowledge on the diversity and ecology of this cryptic group. There is, therefore, an urgent need to study the distribution and landscape ecology of land snails to ensure their effective conservation.
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Digweed, Scott C. "SELECTION OF TERRESTRIAL GASTROPOD PREY BY CYCHRINE AND PTEROSTICHINE GROUND BEETLES (COLEOPTERA: CARABIDAE)." Canadian Entomologist 125, no. 3 (1993): 463–72. http://dx.doi.org/10.4039/ent125463-3.
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AbstractI examined the relative feeding preferences of five carabid beetle species for terrestrial gastropod prey. Scaphinotus marginatus Fischer, thought to be a snail specialist, discriminated among seven species of potential prey by size and species, with the slug Deroceras reticulatum (Müller) being the most preferred. Scaphinotus marginatus appears to use its elongated and narrowed mouthparts, head, and thorax to prey upon terrestrial snails without having to crush their shells. The relative feeding preferences of four pterostichine generalist predators (Pterostichus adstrictus Eschscholtz, P. pensylvanicus LeConte, P. protractus LeConte, and P. surgens LeConte) for two species of small snails [Discus cronkhitei (Newcomb) and Euconulus fulvus (Müller)] also were examined. Although all four carabids ate E. fulvus in varying proportions, only P. protractus consumed D. cronkhitei. I suggest that snail shell thickness and differing feeding preferences affect which snail species are eaten by these pterostichines.
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Chen, Y. J., J. Y. Wu, C. T. A. Chen, and L. L. Liu. "Effects of low-pH stress on shell traits of the dove snail, <i>Anachis misera</i>, inhabiting shallow-vent environments off Kueishan Islet, Taiwan." Biogeosciences 12, no. 9 (2015): 2631–39. http://dx.doi.org/10.5194/bg-12-2631-2015.
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Abstract. The effects of naturally acidified seawater on shell traits were quantified through the comparison of dove snails (Family: Columbellidae) Anachis misera from vent environments with Euplica sp. from non-vent sites in northeastern Taiwan. Samples of A. misera were collected around a shallow vent (24.8341° N, 121.96191° E), which included the east, south, southwest, and northwest sites. An absence of Anachis snails was found in the most acidic north site (pH 7.19–7.25). Based on the similarities of protein expression profiles, the Anachis snails were classified into two groups, i.e., V-South (pH 7.78–7.82) and V-Rest (pH 7.31–7.83). Comparing their shell traits to the non-vent Euplica sp. from Da-xi (DX) and Geng-fang (GF) (pH 8.1–8.2), a difference in shell shape (shell width : shell length) was found, with the populations having more globular shells than the non-vent ones. The means of shell width were significantly different among sites (p < 0.01), with a descending order of GF > DX > V-South and V-Rest. The relationships of shell length to total weight were curvilinear for both Anachis and Euplica snails. The logarithmically transformed slopes differed significantly among sites, and the mean body weight of the GF population was greater than that of the others (p < 0.01). Positive correlations between shell length and shell thickness of body whorl (T1) and penultimate whorl (T2) were only observed in non-vent GF and DX populations. Anachis snails from vent sites were thinner in T1 and T2 compared to the Euplica snails from non-vent sites (p < 0.05). Within each vent group, shell thickness between T1 and T2 was insignificantly different. Between vent groups, T1 and T2 from V-Rest showed a decrease of 10.6 and 10.2%, respectively, compared to V-South ones. The decrease of T1 and T2 between vent Anachis snails and non-vent Euplica snails was as great as 55.6 and 29.0%, respectively. This was the first study to compare snail's morphological traits under varying shallow-vent stresses with populations previously classified by biochemical responses. Overall, the shallow-vent-based findings provide additional information from subtropics on the effects of acidified seawater on gastropod snails in natural environments.
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Fröberg, Lars, Anette Baur, and Bruno Baur. "Differential herbivore damage to calcicolous lichens by snails." Lichenologist 25, no. 1 (1993): 83–95. http://dx.doi.org/10.1006/lich.1993.1015.
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AbstractA laboratory experiment was conducted to determine the damage caused by snail grazing to 35 calcicolous lichen species and cyanobacteria from the Baltic island of Oland, Sweden. Individuals of four species of land snails (Balea perversa, Chondrina cliema, Clausilia bidentata and Helicigona lapicida) were allowed to graze on identified lichen species growing on pieces of limestone. Snail grazing on thalli and ascocarps was classified into four categories ranging from no damage to completely eaten. In general, some lichen species were heavily grazed, whereas others were only slightly damaged or not injured. Aspiciha calcarea, Tephromela atra and Verrucaria nigrescens were preferred by all snail species except Chondrina cliema. In general, lichen thalli that were not immersed in the calcareous rock and cyanobacteria were preferred, whereas ascocarps were avoided by one of the snail species (C. clienta). Immersed perithecia with a carbonized outer layer were avoided by all snail species except C. bidentata. Possibilities of chemical and mechanical defence properties in calcicolous lichens are discussed.
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Brodie, Gilianne, Gary M. Barker, Froseann Stevens, and Monifa Fiu. "Preliminary re-survey of the land snail fauna of Rotuma: conservation and biosecurity implications." Pacific Conservation Biology 20, no. 1 (2014): 94. http://dx.doi.org/10.1071/pc140094.
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In May 2012 Rotuma Island, the main island of the remote Rotuma Group (Fiji), was surveyed to document the composition of the non-native land snail fauna and to investigate if populations of previously recorded native land snail species persist. From sampling at nine locations, twenty-one land snail species from eleven gastropod families were found. Of these, eight species are non-native and two of these Parmarion martensi Simroth, 1893 and Quantula striata (Gray, 1834) (Ariophantidae) are new records for the Rotuma Group. Ten of the 13 species of native land snails found — including the endemic partulid Partula leefi E. A. Smith, 1897 and the rhytidid Delos gardineri (E. A. Smith, 1897) — were detected only as empty shells. The native Ouagapia perryi (E. A. Smith, 1897) and the endemic Succinea rotumana E. A. Smith, 1897 and Sinployea rotumana (E. A. Smith, 1897) remain undetected on Rotuma Island since their first collection in 1897. The non-native, invasive predatory flatworm, Platydemus manokwari, was also found and represents a major threat to the island’s land snail fauna. This non-native species appears to be absent in many other parts of the Fiji Island archipelago and thus a re-evaluation of existing quarantine measures is required to address its potential spread to non-invaded areas. Comparisons with earlier surveys indicate a shift in the structure of the Rotuman land snail fauna over a 115-year period, with declining native components and increasing prevalence of non-native species. Further sampling, focusing on residual native habitat in less accessible areas such as coastal cliffs and offshore islets, is urgently needed to establish the conservation status of Rotuman native land snails and determine the threat posed by both, non-native snails and P. manokwari.
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Baker, GH. "The Life-History, Population-Dynamics and Polymorphism of Cernuella-Virgata (Mollusca, Helicidae)." Australian Journal of Zoology 36, no. 5 (1988): 497. http://dx.doi.org/10.1071/zo9880497.
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The terrestrial snail, Cernuella virgata, was sampled over 3 years in a permanent pasture and adjacent roadside vegetation at Mt Benson, S.A. C. virgata has an annual life cycle, breeding from autumn to winter. Shell size and the presence of a rib which forms on the inner margin of the shell aperture of large snails during early autumn were used to separate the two cohorts of snails (adults and their young) present during winter. Snails (>6 mm shell diameter) were most abundant in the pasture in spring and in the roadside vegetation in summer. I discuss the importance of dispersal between habitats in contributing to these changes in abundance. C. virgata was aggregated within the pasture at all times of the year, but especially during summer when large proportions of the population (>50%) aestivated on the weed Marrubium vulgare. C. virgata and another abundant snail, Theba pisana, were rarely found together in large numbers in small areas (0.25 m2) within the pasture although both had similar general distributions. Shell sizes and banding patterns of C. virgata varied geographically throughout south-eastern Australia. No correlations between climate and size and banding were found. Size was, however, inversely related to population density. At Mt Benson, unbanded snails were slightly more prevalent in the pasture compared with the roadside vegetation. Shell growth and formation of the marginal rib of C. virgata were advanced by exposure to warm, moist conditions in a glasshouse in summer, but maturation of the albumen gland, and hence reproduction, was not.
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Abraham, Isaac, Hamid R. Khan, and A. S. M. Saleuddin. "The elevation of cAMP levels by a putative diuretic hormone in the osmoregulatory organs of the freshwater snail Helisoma duryi." Canadian Journal of Zoology 69, no. 11 (1991): 2800–2804. http://dx.doi.org/10.1139/z91-394.
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In the freshwater snail Helisoma duryi, the kidney and mantle are major organs for osmoregulation and the visceral ganglion is the putative source of diuretic hormone. The role of cAMP as a second messenger in hormonal regulation of these organs has been studied. Hypo-osmotic treatment of snails raised the levels of intracellular cAMP in their kidney and mantle tissues. Forskolin, isobutylmethylxanthine, and theophylline also increased the levels of intracellular cAMP in these tissues. In addition, when these tissues from snails that were acclimated in isosmotic medium were treated in vitro with extracts of visceral ganglion of snails that were acclimated in hypo-osmotic medium, elevated levels of cAMP were observed, 12-fold for the kidney tissue and 4-fold for the mantle tissue. The stimulatory substance from the visceral ganglion was heat stable but labile to proteolytic digestion. In similar in vitro experimental conditions, hemolymph taken from hypo-osmotically treated snails also raised levels of cAMP. It is suggested that in H. duryi cAMP is involved as a second messenger for hormonal osmoregulation by kidney and mantle, and that the putative diuretic hormone is a neuropeptide.
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CURTIS, L. A. "Ecology of larval trematodes in three marine gastropods." Parasitology 124, no. 7 (2002): 43–56. http://dx.doi.org/10.1017/s0031182002001452.
Full textAbstract:
To comprehend natural host–parasite systems, ecological knowledge of both hosts and parasites is critical. Here I present a view of marine systems based on the snail Ilyanassa obsoleta and its trematodes. This system is reviewed and two others, those of the snails Cerithidea californica and Littorina littorea, are then summarized and compared. Trematodes can profoundly affect the physiology, behaviour and spatial distribution of hosts. Studying these systems is challenging because trematodes are often embedded in host populations in unappreciated ways. Trematode prevalence is variable, but can be high in populations of all three hosts. Conditions under which single- and multiple-species infections can accumulate are considered. Adaptive relations between species are likely the most important and potentials for adaptation of parasites to hosts, hosts to parasites, and parasites to other parasites are also considered. Even if colonization rate is low, a snail population can develop high trematode prevalence, if infections persist long and the host is long-lived and abundant. Trematodes must be adapted to use their snail hosts. However, both I. obsoleta and L. littorea possess highly dispersed planktonic larvae and trematode prevalence is variable among snail populations. Host adaptation to specific infections, or even to trematodes in general, is unlikely because routine exposure to trematodes is improbable. Crawl-away juveniles of C. californica make adaptation to trematodes in that system a possibility. Trematode species in all three systems are not likely adapted to each other. Multiple-species infections are rare and definitive hosts scatter parasite eggs among snail populations with variable prevalences. Routine co-occurrence of trematodes in snails is thus unlikely. Adaptations of these larval trematodes to inhabit the snail host must, then, be the basis for what happens when they do co-occur.