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1
Moltschaniwskyj, Natalie A. "Understanding the process of growth in cephalopods." Marine and Freshwater Research 55, no. 4 (2004): 379. http://dx.doi.org/10.1071/mf03147.
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Many cephalopod species grow throughout their lifetime. Critically, this means that they lack an asymptotic phase of growth, when, for a substantial part of the lifetime, growth slows and body size increases minimally. Understanding the form of the growth curve requires an understanding of the growth processes operating at several biological levels including the relative growth of organs, muscle fibre production and growth, and at the level of proximal composition and protein synthesis. There are key differences in growth processes between fish and cephalopods; cephalopods have a sac-like body form that provides greater surface area for respiration, continuous production of new muscle fibres that ensures a supply of somatic material for growth, and high retention of synthesised protein. These characteristics provide process-orientated explanations for non-asymptotic growth in cephalopods. However, differences found in growth curves of laboratory-reared animals (two-phase growth curve) and of wild animals (single growth curve) suggests that future work will be needed to resolve this paradox. We need to determine the generality of growth processes observed to date, and how biotic and abiotic factors modify these processes during the lifetime of the animals.
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Rodhouse, P. G., U. Piatkowski, and C. C. Lu. "Southern Ocean cephalopods: life cycles and populations (Proceedings of the symposium held at Kings College Cambridge, 5–9 July 1993)." Antarctic Science 6, no. 2 (1994): 136. http://dx.doi.org/10.1017/s0954102094000192.
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The first systematic sampling in the Southern Ocean to capture cephalopods took place 120 years ago aboard HMS Challenger. Over the next century taxonomic knowledge was advanced by expeditions including the Mission du Cap Horn (France), the Valdivia Deep Sea Expedition (Germany), the Discovery expeditions (UK) the Eltanin (USA) and Academic Knipovitch (USSR). Over the last decade Southern Ocean cephalopod research has at last progressed beyond the descriptive phase and is rapidly joining other fields of Antarctic marine biology in its concerns with population biology and trophic systems, Although much taxonomic work remains to be done, ecological studies on the role of cephalopods in the diet of predators has been facilitated by advances in the identification of cephalopod beaks, development of opening-closing nets has allowed fine-scale distribution studies, and as methods for the study of growth, diet and biochemical genetics have advanced, so these have been applied to Southern Ocean cephalopods.
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Cherel, Yves, and Keith A. Hobson. "Stable isotopes, beaks and predators: a new tool to study the trophic ecology of cephalopods, including giant and colossal squids." Proceedings of the Royal Society B: Biological Sciences 272, no. 1572 (2005): 1601–7. http://dx.doi.org/10.1098/rspb.2005.3115.
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Cephalopods play a key role in the marine environment but knowledge of their feeding habits is limited by lack of data. Here, we have developed a new tool to investigate their feeding ecology by combining the use of their predators as biological samplers together with measurements of the stable isotopic signature of their beaks. Cephalopod beaks are chitinous hard structures that resist digestion and the stable isotope ratios of carbon (δ 13 C) and nitrogen (δ 15 N) are indicators of the foraging areas and trophic levels of consumers, respectively. First, a comparison of δ 13 C and δ 15 N values of different tissues from the same individuals showed that beaks were slightly enriched in 13 C but highly impoverished in 15 N compared with lipid-free muscle tissues. Second, beaks from the same species showed a progressive increase in their δ 15 N values with increasing size, which is in agreement with a dietary shift from lower to higher trophic levels during cephalopod growth. In the same way, there was an increase in the δ 15 N signature of various parts of the same lower beaks in the order rostrum, lateral walls and wings, which reflects the progressive growth and chitinization of the beaks in parallel with dietary changes. Third, we investigated the trophic structure of a cephalopod community for the first time. Values of δ 15 N indicate that cephalopods living in slope waters of the subantarctic Kerguelen Islands ( n =18 species) encompass almost three distinct trophic levels, with a continuum of two levels between crustacean- and fish-eaters and a distinct higher trophic level occupied by the colossal squid Mesonychoteuthis hamiltoni . δ 13 C values demonstrated that cephalopods grow in three different marine ecosystems, with 16 species living and developing in Kerguelen waters and two species migrating from either Antarctica ( Slosarczykovia circumantarctica ) or the subtropics (the giant squid Architeuthis dux ). The stable isotopic signature of beaks accumulated in predators' stomachs therefore revealed new trophic relationships and migration patterns and is a powerful tool to investigate the role of the poorly known cephalopods in the marine environment.
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LEFKADITOU, E., and P. BEKAS. "Analysis of beak morphometry of the horned octopus Eledone cirrhosa (Cephalopoda: Octopoda) in the Thracian Sea (NE Mediterranean)." Mediterranean Marine Science 5, no. 1 (2004): 143. http://dx.doi.org/10.12681/mms.219.
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Cephalopod beaks are chitinous structures situated in the buccal mass lying at the base of their arms. Because they are among the few hard structures of cephalopods with high resistance to erosion during digestive process in predator stomachs, the study of the beak morphometry is of major importance for the species taxonomy, as well as, for the size estimation of the cephalopods consumed. In this study new information is provided on the dimensions and pigmentation process of the upper and lower beak of the horned octopus Eledone cirrhosa derived from 67 female and 47 male specimens caught by trawl in the Thracian Sea (NE Mediterranean). The growth of both beaks was allometric in relation to the mantle length and body weight. According to the results of covariance analysis, no difference was found in growth pattern of beaks between sexes. Four degrees of pigmentation were identified in both upper and lower beaks, the darkening process starting in females at a smaller size.
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Tan, Hanrong, Andrew G. Hirst, Douglas S. Glazier, and David Atkinson. "Ecological pressures and the contrasting scaling of metabolism and body shape in coexisting taxa: cephalopods versus teleost fish." Philosophical Transactions of the Royal Society B: Biological Sciences 374, no. 1778 (2019): 20180543. http://dx.doi.org/10.1098/rstb.2018.0543.
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Metabolic rates are fundamental to many biological processes, and commonly scale with body size with an exponent ( b R ) between 2/3 and 1 for reasons still debated. According to the ‘metabolic-level boundaries hypothesis', b R depends on the metabolic level ( L R ). We test this prediction and show that across cephalopod species intraspecific b R correlates positively with not only L R but also the scaling of body surface area with body mass. Cephalopod species with high L R maintain near constant mass-specific metabolic rates, growth and probably inner-mantle surface area for exchange of respiratory gases or wastes throughout their lives. By contrast, teleost fish show a negative correlation between b R and L R . We hypothesize that this striking taxonomic difference arises because both resource supply and demand scale differently in fish and cephalopods, as a result of contrasting mortality and energetic pressures, likely related to different locomotion costs and predation pressure. Cephalopods with high L R exhibit relatively steep scaling of growth, locomotion, and resource-exchange surface area, made possible by body-shape shifting. We suggest that differences in lifestyle, growth and body shape with changing water depth may be useful for predicting contrasting metabolic scaling for coexisting animals of similar sizes. This article is part of the theme issue ‘Physiological diversity, biodiversity patterns and global climate change: testing key hypotheses involving temperature and oxygen’.
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Martínez, Pilar, Vera Bettencourt, Ángel Guerra, and Natalie A. Moltschaniwskyj. "How temperature influences muscle and cuttlebone growth in juvenile cuttlefish (Sepia elliptica) (Mollusca: Cephalopoda) under conditions of food stress." Canadian Journal of Zoology 78, no. 10 (2000): 1855–61. http://dx.doi.org/10.1139/z00-115.
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Environmental factors influencing growth during the first stages of an animal's life cycle are determinative. External factors have often been implicated in the determination of rates of development of teleost larvae; however, the first stages of development of cephalopods remain poorly studied. In view of the fact that previous studies had shown that temperature is an important factor affecting cephalopod growth, particularly at high food concentrations, in this study the effect of temperature under conditions of non-satiation were investigated. A food-stress experiment was carried out for 75 days on 80 juvenile cuttlefish (Sepia elliptica) reared under two temperatures (25 and 30°C) and two food rations of glass shrimps Acetes sibogae australis at high and low proportions (2:1, respectively). We examined the effect of temperature and feeding regime on the growth of the whole animal, cuttlebone, and muscle tissue. Mantle-muscle blocks were 15% larger at 30°C than at 25°C, with the greatest difference in the middle mantle region (21% more at 30°C), whereas cuttlebone and somatic growth varied when the combination that included either the higher temperature or the higher food ration was used. Thus, at 30°C under the low feeding regime, final dorsal mantle length (DML) and cuttlebone growth index (CGI) were higher; however, at 25°C, final DML, CGI, and survivorship increased under the higher feeding regime. It was concluded that food scarcity may exaggerate the effect of small temperature differences. The results are discussed in the light of previous findings on the growth of other cuttlefish species, cephalopods, and teleosts.
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Jackson, George D., and J. Howard Choat. "Growth in Tropical Cephalopods: An Analysis Based on Statolith Microstructure." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 2 (1992): 218–28. http://dx.doi.org/10.1139/f92-026.
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Validated size-at-age data are presented for two tropical squid species (Loliolus noctiluca and Loligo chinensis) and a sepioid (Idiosepius pygmaeus). Estimates of age were obtained from daily increments in the statolith. All species reached adult size in less than 200 d. For each species, growth in mantle length was linear over the sizes sampled. In L. chinensis, growth was fastest during December–January (summer), with males showing faster growth rates than females. For I. pygmaeus, females generally had a higher growth rate than males. The slowest growth rates for both sexes occurred in the August–September (winter) period. The size-at-age data indicated rapid linear or exponential growth and a short life span of less than 1 yr. In contrast, growth curves generated from analysis of length frequency data (ELEFAN software package) suggested an asymptotic growth curve and ages in excess of 3 yr, and such analyses therefore appear inappropriate. The results of this study and a review of the literature revealed that rapid growth and short life span is the norm for pelagic cephalopods, with tropical species growing considerably faster than their temperate counterparts.
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Semmens, J. M., G. T. Pecl, R. Villanueva, et al. "Understanding octopus growth: patterns, variability and physiology." Marine and Freshwater Research 55, no. 4 (2004): 367. http://dx.doi.org/10.1071/mf03155.
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Octopuses are generally characterised by rapid non-asymptotic growth, with high individual variability. However, in situ octopus growth is not well understood. The lack of an ageing method has resulted in the majority of our understanding of octopus growth coming from laboratory studies. Despite not being applicable to cephalopods, Modal Progression Analysis (MPA) of length–frequency data is the most common method for examining in situ octopus growth. Recently, counting growth increments in beaks and vestigial shells, and quantifying lipofuscin in brain tissue, have all shown promise for the ageing octopus. Octopuses generally demonstrate two-phase growth in the laboratory, with physiological changes possibly associated with the switch between an initial rapid exponential phase and a slower power growth phase. Temperature and food ration and quality are key factors influencing the initial growth phase. Temperature, however, does not appear to affect the second phase in any consistent way, perhaps because maturity stage can influence the growth response. There may be basic differences in the mechanisms of octopus muscle growth compared with that of other cephalopods. Furthermore, higher relative maintenance energy expenditure, along with the low energy content of their prey, may account for the relatively slow growth of deep-sea octopuses compared to littoral species.
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Hanlon, R. T., J. P. Bidwell, and R. Tait. "Strontium is required for statolith development and thus normal swimming behaviour of hatchling cephalopods." Journal of Experimental Biology 141, no. 1 (1989): 187–95. http://dx.doi.org/10.1242/jeb.141.1.187.
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When cephalopod eggs were incubated in artificial sea water it was found that they sometimes resulted in hatchlings with defects of the statocyst suprastructure, leading to the severe behavioural defect of uncontrolled swimming. Experiments in defined media (seven basic salts mixed in deionized water) with seven species of cephalopods demonstrated clearly that there is 100% normal development of the aragonite statoliths when strontium levels were 8 mg l-1. Conversely, statoliths did not develop when strontium was absent. In cuttlefish, the growth of the cuttlebone was also affected adversely when strontium was absent. In mariculture production tanks, supplementing commercial artificial sea water with strontium to normal levels of 8 mg l-1 almost eliminated the occurrence of abnormal hatchlings. Circumstantial evidence indicates that there is a critical window in development during which strontium is required for normal development. The role of strontium in biomineralization during embryogenesis is unknown, but it appears to be important in the Mollusca.
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Lopes, S. S., M. L. Coelho, and J. P. Andrade. "Analysis of Oocyte Development and Potential Fecundity of the Squid Loligo Vulgaris from the Waters of Southern Portugal." Journal of the Marine Biological Association of the United Kingdom 77, no. 3 (1997): 903–6. http://dx.doi.org/10.1017/s0025315400036262.
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This study constitutes a first approach of the use of a stereological method for estimating potential fecundity in cephalopods. Squid samples were taken in two regions from the south coast of Portugal. In Olhäo, commercial trawlers provided mainly immature squid during winter. In Quarteira, a summertime traditional jigg fishery provided maturing and mature squid, which were used in the fecundity estimates. A total of 38 female squid, Loligo vulgaris (Cephalopoda: Loliginidae), from all maturity stages were analysed. The results revealed that: (1) the development of the ovaries is monocyclic and the oocyte growth and development is asynchronous; (2) oogenesis proceeds in six histological stages, showing statistically different oocyte maximum diameters; and (3) the best estimate of potential fecundity seems to be obtained by counting all oocytes in the ovaries of the mature females in maturity stage IV
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KELLER, S., J. P. ROBIN, M. VALLS, M. GRAS, M. CABANELLAS-REBOREDO, and A. QUETGLAS. "The use of Depletion Methods to assess Mediterranean cephalopod stocks under the current EU Data Collection Framework." Mediterranean Marine Science 16, no. 3 (2015): 513. http://dx.doi.org/10.12681/mms.1127.
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Fuelled by the raising importance of cephalopod fisheries in Europe, there have been demands from scientists and stakeholders for their assessment and management. However, little has been done to improve the data collection in order to analyse cephalopod populations under the EU Data Collection Framework (DCF). While the DCF allows member states to design flexible national sampling programmes, it establishes the minimum data requirements (MDR) each state is obliged to fulfil. In this study, it was investigated whether such MDR currently set by the DCF allow the application of depletion models (DMs) to assess European cephalopod stocks. Squid and cuttlefish fisheries from the western Mediterranean were used as a case study. This exercise sheds doubt on the suitability of the MDR to properly assess and manage cephalopod stocks by means of DMs. Owing to the high plasticity of life-history traits in cephalopod populations, biological parameters should be estimated during the actual depletion period of the fished stocks, in contrast with the triennial sampling established by the DCF. In order to accurately track the depletion event, the rapid growth rates of cephalopods implies that their populations should be monitored at shorter time scales (ideally weekly or biweekly) instead of quarterly as required by the DCF. These measures would not demand additional resources of the ongoing DCF, but a redistribution of sampling efforts during the depletion period. Such changes in the sampling scheme could be designed and undertaken by the member states or directly integrated as requirements.
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Grist, Eric P. M., and George D. Jackson. "Energy balance as a determinant of two-phase growth in cephalopods." Marine and Freshwater Research 55, no. 4 (2004): 395. http://dx.doi.org/10.1071/mf03154.
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Many cephalopods exhibit early exponential growth, which abruptly shifts to a much slower rate. Using a simple model of the energy balance between intake from food and expenditure in growth plus metabolism, we consider how the two-phase growth pattern may be explained in terms of energy conservation. We determine the post-hatch size and age at which exponential growth would be expected to terminate. The model is tested with laboratory hatchling data obtained for the giant Australian cuttlefish Sepia apama. Together with growth data obtained for a related species, Sepia officinalis, model projections for critical transition size and age interestingly suggest that the metabolism of S. apama in the natural habitat may be three to four times higher than in captivity. A sensitivity analysis indicates that the critical transition size is in general more sensitive than critical transition time to any invoked changes in metabolic rate.
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Moltschaniwskyj, N. A., and C. G. Carter. "Protein Synthesis, Degradation, and Retention: Mechanisms of Indeterminate Growth in Cephalopods." Physiological and Biochemical Zoology 83, no. 6 (2010): 997–1008. http://dx.doi.org/10.1086/656387.
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Pohle, Alexander, Christian Klug, Ursula Toom, and Björn Kröger. "Conch structures, soft-tissue imprints and taphonomy of the Middle Ordovician cephalopod Tragoceras falcatum from Estonia." Fossil Imprint 75, no. 1 (2019): 70–78. http://dx.doi.org/10.2478/if-2019-0006.
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Abstract Tragoceras falcatum (Schlotheim, 1820) is a common, loosely coiled estonioceratid (Tarphycerida, Cephalopoda) occurring in the Kunda Regional Stage (early Darriwilian, Middle Ordovician) of Estonia. Although the species is quite well-known, we document some features for the first time. For example, one specimen from the Harku quarry (Estonia) with a phosphatized replacement shell exhibits growth halts (megastriae) on the body chamber. As they are not preserved in smaller specimens, we suggest that these megastriae formed at the approach of maturity, possibly also reflecting sexual dimorphism and cycles of reproduction (iteroparity?). Additionally, the specimen shows minute soft-tissue imprints (drag bands and pseudosutures). These imprints are comparable to patterns in other cephalopods such as ammonoids, bactritids and other nautiloids, but have not yet been reported from Palaeozoic nautiloids. However, they might have been misinterpreted as oncomyarian muscle attachment scars previously. Lastly, we discuss the taphonomy of the specimen, which was encrusted by multiple bryozoan colonies post-mortem. Furthermore, it shows questionable traces of bioerosion.
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Vidal, Erica A. G., Manuel Haimovici, and Vivian C. S. Hackbart. "Distribution of paralarvae and small juvenile cephalopods in relation to primary production in an upwelling area off southern Brazil." ICES Journal of Marine Science 67, no. 7 (2010): 1346–52. http://dx.doi.org/10.1093/icesjms/fsq080.
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Abstract Vidal, E. A. G., Haimovici, M., and Hackbart, V. C. S. 2010. Distribution of paralarvae and small juvenile cephalopods in relation to primary production in an upwelling area off southern Brazil. – ICES Journal of Marine Science, 67: 1346–1352. The distribution of paralarvae and small juvenile cephalopods sampled by a rectangular midwater trawl (opening area 8 m2) over the continental shelf off Cape Santa Marta Grande, southern Brazil (28°09′S–29°56′S) during spring 1989 is discussed. An intrusion of Brazil Current Tropical Water (22°C; 36.5) separates warm, less-saline water (22°C; 35.2) from cooler, more-saline water (15°C; 36.4). Prevailing northeasterly winds led to upwelling of South Atlantic Central Water over the shelf, promoting high Chl a concentrations. Three species constituted 99% of the 628 cephalopods collected: Illex argentinus (n = 540; 4–40 mm mantle length, ML), Argonauta nodosa (n = 46; 2–19 mm ML), and Loligo sanpaulensis (n = 42, 2–21 mm ML). Segregation of I. argentinus juveniles of similar size suggests school formation as small as 10 mm ML. The presence of mature males along with fertilized female A. nodosa indicates mating early in life. There was a consistent and direct link between high plankton production and high densities of juvenile cephalopods through a short and ecologically efficient food chain. The relationship between production, pycnocline intensity, and the density of paralarvae and juveniles revealed suitable conditions for survival and growth during the upwelling season.
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Lewis, Andrew R., and J. Howard Choat. "Spawning Mode and Reproductive Output of the Tropical Cephalopod Idiosepius pygmaeus." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 1 (1993): 20–28. http://dx.doi.org/10.1139/f93-003.
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Reproductive biology of the tropical sepioid cephalopod Idiosepius pygmaeus was investigated in wild specimens and in individuals maintained in aquaria through the adult life span. This species produced multiple egg batches over 80% of the observable adult weight range, indicating a coordination of reproductive and somatic growth. Reproductive output was consistent within, but variable between, individuals. Oocyte synthesis and maturation occur continuously after sexual maturation has been reached. Senescence and death are not related to an exhaustion of reproductive potential. On average, captive female I. pygmaeus with access to unlimited food produced 640 eggs in 11 batches over 18 d. When reproductive output was expressed as a ratio of dry female body weight, on average, specimens had incorporated five times their body weight into eggs and egg coatings. Under food stress, captive specimens laid fewer eggs but maintained egg size and periodicity of egg laying. Food stress had no effect on either laying duration or weight at death. This study provides further evidence that terminal spawning modes are not ubiquitous amongst cephalopods.
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Moltschaniwskyj, N. A., and G. D. Jackson. "Growth and tissue composition as a function of feeding history in juvenile cephalopods." Journal of Experimental Marine Biology and Ecology 253, no. 2 (2000): 229–41. http://dx.doi.org/10.1016/s0022-0981(00)00257-4.
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Kadri, Hasna, Sondes Marouani, Mohamed Nejmeddine Bradai, and Abderrahmen Bouaïn. "Diet and feeding strategy of thornback ray, Raja clavata (Chondrichthyes: Rajidae) from the Gulf of Gabes (Tunisia—Central Mediterranean Sea)." Journal of the Marine Biological Association of the United Kingdom 94, no. 7 (2014): 1509–16. http://dx.doi.org/10.1017/s0025315414000587.
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Food and feeding strategy of the thornback ray, Raja clavata, were studied from stomach contents analysis of specimens caught monthly in the Gulf of Gabes. The data were analysed according to sex, size and season. At total of 1280 stomachs was examined, from specimens ranging from 14 to 110 cm total length (TL), of which 1076 (83.98%) contained food. Thornback ray feed mainly on teleosts, crustaceans and cephalopods, whereas gastropods and polychaetes are occasionally consumed. Significant differences were found between the diets of males and females; however, ontogenetic changes were also detected, with crustaceans constituting the greatest proportion of the diet of smaller rays. Both teleosts and cephalopods increased in importance with growth of the skates. Prey diversity increased with size; large and mobile prey species were more commonly found in the diet of larger skates. Diet composition showed seasonal variations. Quantitative analyses and graphical methods indicate that the thornback ray is a generalist feeder.
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Arkhipkin, Alexander I. "Statoliths as 'black boxes' (life recorders) in squid." Marine and Freshwater Research 56, no. 5 (2005): 573. http://dx.doi.org/10.1071/mf04158.
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The present study presents an overview of recent developments in statoliths studies. Statoliths are calcareous structures located in the equilibrium organs of cephalopods, which serve to detect body accelerations during movement in water. They are perfect ‘black boxes’ because they record a lot of information about the lives of squid and cuttlefish. For instance, it is possible to reveal the hatchling size and temperature of embryonic development, estimate age and growth rates of the animal with daily precision, date life transitions, analyse possible migratory routes and population structure of squid using trace element analysis, and even reveal how many spawning events a given animal has had by analysing statolith microstructure. Furthermore, because the paralarval statolith is embedded completely within the adult statolith, its features can be used to identify cephalopod paralarvae, which are sometimes very different from adult animals. The shape of statoliths is physiologically specific, which enables the determination of the movement pattern of the animal. Statoliths are usually one of the few remains of squid in fossil records, and their features can be used to infer ideas about the life styles of extinct species.
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Niko, Shuji. "Orthoceratid cephalopods from the Early Devonian Fukuji Formation of Gifu Prefecture, central Japan." Journal of Paleontology 67, no. 2 (1993): 210–16. http://dx.doi.org/10.1017/s0022336000032133.
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Gedinnian (Early Devonian) orthoceratid cephalopods were previously not well known in Japan. Five species are described from the Fukuji Formation of Gifu Prefecture, central Japan: Michelinoceras yamakoshii n. sp., Michelinoceras yoshikiense n. sp., Plagiostomaceras? sp., Polygrammoceras sp., and Metaspyroceras insignis n. sp. Growth and position of the cameral deposits in Michelinoceras indicate that the deposits precipitated from cameral fluids and living Michelinoceras maintained the shell horizontally in swimming orientation.
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Ward, Peter Douglas. "Periodicity of chamber formation in chambered cephalopods: evidence from Nautilus macromphalus and Nautilus pompilius." Paleobiology 11, no. 4 (1985): 438–50. http://dx.doi.org/10.1017/s0094837300011726.
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The growth rates of ammonites and extinct nautiloids have been estimated in two ways: through analyses of shell growth lines and by analyzing the patterns of oxygen isotopic values from successive septa. In both types of studies, it has been assumed that the amount of time between successive chamber formation events is approximately constant. This assumption has never been tested with living cephalopods, however. To examine this, 10 immature Nautilus pompilius and two immature N. macromphalus were maintained in a surface aquarium for a period of 1 yr and periodically radiographed. The radiographs allowed direct observation of chamber formation events and apertural shell growth. During this observational period 61 separate chamber formation events were observed in the nautiluses. The time between separate chamber formation events increased in successively produced chambers, and varied from a minimum of 2–3 wk in a specimen of 45-mm shell diameter to a maximum of 13–15 wk in a specimen of 132-mm shell diameter. Unlike interval of chamber formation, which increased during ontogeny, rate of apertural shell growth showed no observable rate increase or decrease during ontogeny prior to maturity. With the onset of maturity, as marked by the shell characteristics defined by Collins et al. (1980), apertural shell growth rates dropped markedly, and ceased coincident with the removal of the last volumes of cameral liquid in the last formed, approximated chamber. Both rate of apertural shell growth and septal spacing were affected by degree of shell breakage.
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Tajika, Amane, and Christian Klug. "How many ontogenetic points are needed to accurately describe the ontogeny of a cephalopod conch? A case study of the modern nautilid Nautilus pompilius." PeerJ 8 (March 26, 2020): e8849. http://dx.doi.org/10.7717/peerj.8849.
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Recent advancements in tomographic techniques allow for detailed morphological analysis of various organisms, which has proved difficult in the past. However, the time and cost required for the post-processing of highly resolved tomographic data are considerable. Cephalopods are an ideal group to study ontogeny using tomography as the entire life history is preserved within a conch. Although an increasing number of studies apply tomography to cephalopod conchs, the number of conch measurements needed to adequately characterize ontogeny remains unknown. Therefore, the effect of different ontogenetic sampling densities on the accuracy of the resultant growth trajectories needs to be investigated. Here, we reconstruct ontogenetic trajectories of a single conch of Nautilus pompilius using different numbers of ontogenetic points to assess the resulting accuracies. To this end, conch parameters were measured every 10°, 30°, 45°, 90°, and 180°. Results reveal that the overall patterns of reconstructed growth trajectories are nearly identical. Relatively large errors appear to occur where growth changes occur, such as the points of hatching and the onset of morphogenetic countdown before the attainment of maturity. In addition, a previously undocumented growth change before hatching was detected when measurements were taken every 10°, 30°, and 45°, though this growth change was obscured when fewer measurements were used (90° and 180°). The lower number of measurements also masks the subtle fluctuating patterns of conch parameters in middle ontogeny. We conclude that the measurements of a conch every 30° and 45° permit a reasonably precise description of conch ontogeny in nautilids. Since ammonoids were likely more responsive to external stimuli than to nautilids, a much denser sampling may be required for ammonoids.
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Somasekharan, Jayasekhar, Harilal K. N, and Parameswaran M. "Coping with the Standards Regime: Analyzing Export Competitiveness of Indian Seafood Industry." Sustainable Agriculture Research 2, no. 1 (2012): 98. http://dx.doi.org/10.5539/sar.v2n1p98.
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<p>In this research paper a Constant Market Share (CMS) approach was employed to learn export performance dynamics of Indian seafood (shrimps and cephalopods) in the major export destinations (EU, USA and select Asian countries), which accounts for a sizeable market for Indian seafood. The Constant Market Share model was used to disintegrate the growth in exports of seafood into market size effect, market composition effect and competitiveness effect. The analysis was performed for the seafood exports for a span of 12 years from the year 1996 to the year 2007, the period during which India had to face severe challenges from evolving food safety regulations in the EU and USA. The analysis was extended to account for the competitiveness at dis-aggregated commodity level. In the present study we observed enhanced competitiveness in the case of cephalopods while shrimp exports were less competitive. To a certain extent it shows that trade facilitating as well as trade restricting effects can coexist as an impact of strict food safety regulations.</p>
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Hu, Marian Y., Yung-Che Tseng, Meike Stumpp, et al. "Elevated seawater Pco2 differentially affects branchial acid-base transporters over the course of development in the cephalopod Sepia officinalis." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 300, no. 5 (2011): R1100—R1114. http://dx.doi.org/10.1152/ajpregu.00653.2010.
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The specific transporters involved in maintenance of blood pH homeostasis in cephalopod molluscs have not been identified to date. Using in situ hybridization and immunohistochemical methods, we demonstrate that Na+/K+-ATPase ( soNKA), a V-type H+-ATPase ( soV-HA), and Na+/HCO3− cotransporter ( soNBC) are colocalized in NKA-rich cells in the gills of Sepia officinalis. mRNA expression patterns of these transporters and selected metabolic genes were examined in response to moderately elevated seawater Pco2 (0.16 and 0.35 kPa) over a time course of 6 wk in different ontogenetic stages. The applied CO2 concentrations are relevant for ocean acidification scenarios projected for the coming decades. We determined strong expression changes in late-stage embryos and hatchlings, with one to three log2-fold reductions in soNKA, soNBCe, socCAII, and COX. In contrast, no hypercapnia-induced changes in mRNA expression were observed in juveniles during both short- and long-term exposure. However, a transiently increased ion regulatory demand was evident during the initial acclimation reaction to elevated seawater Pco2. Gill Na+/K+-ATPase activity and protein concentration were increased by ∼15% during short (2–11 days) but not long-term (42-days) exposure. Our findings support the hypothesis that the energy budget of adult cephalopods is not significantly compromised during long-term exposure to moderate environmental hypercapnia. However, the downregulation of ion regulatory and metabolic genes in late-stage embryos, taken together with a significant reduction in somatic growth, indicates that cephalopod early life stages are challenged by elevated seawater Pco2.
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Kröger, Björn. "Early growth-stages and classification of orthoceridan Cephalopods of the Darriwillian (Middle Ordovician) of Baltoscandia." Lethaia 39, no. 2 (2006): 129–39. http://dx.doi.org/10.1080/00241160600623749.
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Arkhipkin, Alexander I., and Zhanna N. Shcherbich. "Thirty years' progress in age determination of squid using statoliths." Journal of the Marine Biological Association of the United Kingdom 92, no. 6 (2011): 1389–98. http://dx.doi.org/10.1017/s0025315411001585.
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The discovery thirty years ago of daily growth increments in squid statoliths and the development of statolith ageing techniques gave new insight into squid age, growth and metabolism. The techniques have shown that the majority of recent coleoid cephalopods live in the ‘fast lane’, growing rapidly and completing their life cycles in a year or less. Surprisingly, these useful approaches to the study of age and growth in squid have not gained much momentum. Only approximately an eighth of more than 300 squid species have had their basic age assessed and described. Two dozen species are subject to continuing arguments about which increments to consider as daily growth increments. This paper outlines major problems encountered during age determination of squid and suggests ways to improve the techniques and make them applicable to a wider spectrum of species.
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Pecl, G. T., M. A. Steer, and K. E. Hodgson. "The role of hatchling size in generating the intrinsic size-at-age variability of cephalopods: extending the Forsythe Hypothesis." Marine and Freshwater Research 55, no. 4 (2004): 387. http://dx.doi.org/10.1071/mf03153.
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Cephalopods are characterised by extreme variability in size-at-age, with much of this variation attributed to effects of temperature and food. However, even siblings reared under identical conditions display a wide range of sizes after a period of growth. Hatchling size may represent a source of variation encompassed within adult size-at-age data (i) within a given cohort (variation in hatchling size suggests that a cohort’s growth trajectory will have a ‘staggered start’) and (ii) as hatchling size also varies as a function of incubation temperature this will vary across broader scales (i.e. between cohorts). Field-hatchling size data for Sepioteuthis australis were used in simple deterministic simulations, extending Forsythe’s (1993) temperature hypothesis, to investigate the influence of hatchling size on adult size-at-age variability. Within a cohort, our growth projections suggest that after 90 days, a large hatchling growing at a specific constant percentage daily growth rate (%BW day–1), would be approximately double the size of the small hatchling growing at exactly the same rate, irrespective of the growth rate used. When considering growth of different cohorts, decreases in hatchling size, as temperatures increase during a spring/summer spawning season, may be partially counteracting the ‘Forsythe-effect’ of increased growth rate at higher temperatures.
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Di Beneditto, Ana Paula Madeira, and Renata Maria Arruda Ramos. "Biology of the marine tucuxi dolphin (Sotalia fluviatilis) in south-eastern Brazil." Journal of the Marine Biological Association of the United Kingdom 84, no. 6 (2004): 1245–50. http://dx.doi.org/10.1017/s0025315404010744h.
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Age, growth and reproductive parameters related to the marine tucuxi are presented, as well as feeding habits and parasitism. The specimens' age ranged from zero (newborn) to 21 years for males and 0·5 to 30 years for females. In relation to the body dimension, length distributions were bell-shaped for both sexes with male marine tucuxi ranging from 86·0 to 200·0 cm in length and females from 117·5 to 198·0 cm. The body length of new-born and calves varied between 86·0 to 117·5 cm and the postnatal growth curve an asymptotic reached length of 191·0 cm. According to the relationship between age, body length and reproductive characteristics, male and female specimens were considered sexually mature when [ges ]6 years and body length [ges ]180·0 cm and [ges ]6 years and body length [ges ]160·0 cm, respectively. Males and females up to six years old represented around 80% of the captures, indicating a bias towards juveniles and individuals that have yet to reach sexual maturity. The youngest specimen with solid contents in the stomach was 119·0 cm in length and seven months old. The marine tucuxi feeds on neritic prey, preferentially on the teleost fishes Trichiurus lepturus and Porichthys porossisimus, and on the cephalopods Loligo sanpaulensis and L. plei. Back calculation of prey lengths indicated that fish ranged from 1·2 to 106·9 cm and cephalopods from 3·4 to 22·2 cm. The barnacle Xenobalanus globicipitis was recorded attaching to the caudal fin and the helminths Braunina cordiformis, Anisakis typica, Halocercus brasiliensis and Nasitrema sp. were found in the internal organs.
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Challier, Laurence, Matthew R. Dunn, and Jean-Paul Robin. "Trends in age-at-recruitment and juvenile growth of cuttlefish, Sepia officinalis, from the English Channel." ICES Journal of Marine Science 62, no. 8 (2005): 1671–82. http://dx.doi.org/10.1016/j.icesjms.2005.06.006.
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Abstract The cuttlefish Sepia officinalis is an important fishery resource in the English Channel, and one of the largest stocks of cephalopods in the Northeast Atlantic. Cuttlefish live for approximately 2 years and catches consequently depend largely on recruitment. Early life stages were analysed for differences in juvenile growth and age-at-recruitment to the commercial fisheries. Recruits were sampled monthly between October 2000 and June 2003, and pre-recruits from the coastal waters of the UK and France in the summers of 2000 and 2002. Age (days) was determined from statoliths. Although most cuttlefish were recruited during autumn, there was some recruitment throughout the year. Age-at-recruitment varied significantly between season and cohort, but was consistently in the range 3–4 months, so although there was some hatching throughout the year, most cuttlefish hatched during summer. Fitted growth models indicated that the growth rates of pre-recruits (7–59 mm mantle length) were significantly higher in 2002 than in 2000. Spatial differences in growth rate were apparent in 2000, suggesting that pre-recruit growth may depend on local environmental conditions. Pre-recruits and recruits combined (7–106 mm mantle length) also showed significant variation in growth between hatching months and years. Hypotheses explaining the observed patterns of growth and recruitment are presented.
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Guex, Jean. "A generalization of Cope’s rule." Bulletin de la Société Géologique de France 174, no. 5 (2003): 449–52. http://dx.doi.org/10.2113/174.5.449.
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Abstract For numerous shelly invertebrates, Cope’s rule is shown in this paper to merely describe the particular case where volume increase is strictly coupled with diameter or length. Allometries, which are frequently observed in the evolution of the shells’ geometry, mean that their size, volume and surface can vary independently. The consequences of this can be summarized as follows : 1) volume increase not coupled with an increase of diameter or length of the organisms generates increasing involution and/or lateral width in the shell of cephalopods, foraminifera and radiolarians ; 2) an increase of the biomineralizing surface, not coupled with volume increase, generates increasing apparent complexity in the sutures and growth lines in ammonites, and an increase in the complexity and number of chambers in foraminifera.
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Pecl, Gretta T., and Natalie A. Moltschaniwskyj. "Life history of a short-lived squid (Sepioteuthis australis): resource allocation as a function of size, growth, maturation, and hatching season." ICES Journal of Marine Science 63, no. 6 (2006): 995–1004. http://dx.doi.org/10.1016/j.icesjms.2006.04.007.
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Abstract Many cephalopods continue growing while laying multiple egg batches over the adult life, with repro-somatic allocation continuing beyond attainment of reproductive maturity. Many species show extreme individual variation in reproductive investment. Factors driving this variation in adult Sepioteuthis australis were evaluated by examining allocation of energy to somatic and reproductive growth as a function of body shape, growth rate, maturation, and hatching season. Hatching season influence was sex-specific; males hatched in warmer months had greater reproductive investment, faster growth, and better somatic and reproductive condition, whereas females hatched in spring and summer had less reproductive investment. Seasonal impacts on life history resulted in an “alternation of generations”, with slow-growing squid in poor condition and with high levels of reproductive investment producing a generation with completely different life-history characteristics. This suggests that abiotic and biotic conditions that change seasonally could play a large role in determining energy allocated to reproduction. However, this was not driving trade-offs between size and number of offspring. Life-history trade-offs should be detectable as negative correlations between relevant traits. However, in Sepioteuthis australis there was little evidence of trade-offs between reproduction and growth or condition of individuals, suggesting a “live for today” lifestyle.
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Anderson, T. J., and R. C. Babcock Leigh. "Subcutaneous electromagnetic tagging of benthic octopus: a preliminary evaluation." Marine and Freshwater Research 50, no. 3 (1999): 225. http://dx.doi.org/10.1071/mf98152.
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Electromagnetic tags were subcutaneously implanted in the dorsal crown of 28 octopus (20 aquarium tagged; and 8 wild octopus tagged in situ) from two species: Octopus tetricus and O. maorum. Laboratory tagged octopus retained tags for the duration of the study (14 months), as did octopus tagged in the wild (13 weeks). No signs of lesions, physical deterioration, or abnormal behaviours were apparent in either laboratory or field tagged octopus. Tagging had no significant effect on growth trajectories. Both laboratory and field tagged octopus appeared healthy, physically vigorous, maintained voracious apetites, and regularly stalked and attacked vigorous prey (laboratory observations only). Subcutaneously implanted electromagnetic tags enabled individuals to be tagged, and tags to be read in situ with minimal disturbance to the animal. Electromagnetic tagging is a potentially invaluable tool in studying benthic octopus and may have similar value in the study of many cephalopods and other soft bodied organisms.
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Mikheev, P. B., and T. A. Sheina. "Application of the analysis of trace elements composition for calcified structures of fish to solve fundamental and applied scientific tasks: a review." Izvestiya TINRO 200, no. 3 (2020): 688–729. http://dx.doi.org/10.26428/1606-9919-2020-200-688-729.
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Microchemical analysis of calcified structures of fish is a modern technique for determining the origin of fish species and ontogenetic reconstructions of their habitat that can be applied for such tasks as stocks separation in mixed samples, tracking of fish migrations, determining of spawning, feeding or wintering areas, differentiation of fish of artificial and natural origin, growth analysis, age evaluation, etc. The approach is based on analysis of trace elements concentration between the center and periphery of a calcified structure, or precise measurement of the elements and their isotopes concentration in certain sites of sample. The calcified structures most often used for analysis are otoliths, skeleton bones, scales, and also statoliths of lampreys or beaks and statoliths of cephalopods. Specifics of the method application are described with examples of its use for solving diverse tasks of fundamental and applied science, in particular in complex studies of biological resources in the Amur River basin.
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Nicosia, Aldo, Monica Salamone, Salvatore Mazzola, and Angela Cuttitta. "Transcriptional and Biochemical Effects of Cadmium and Manganese on the Defense System ofOctopus vulgarisParalarvae." BioMed Research International 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/437328.
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Due to anthropogenic activities the relative concentrations of cadmium and manganese have increased in the marine environment. Cephalopods are able to accumulate such metals and, as inhabitant of coastal waters,Octopus vulgarisis continuously exposed to anthropogenic activities. Since no study is available on the effects of heavy metals at molecular level in developing octopuses, herein we exposed 1-day-old paralarvae for 24 h to 10, 100, and 1000 μg/L of CdCl2or MnCl2. Cd exerted a concentration-dependent inhibition of survival and a reduction in growth rate was shown while Mn exposure did not affect the survival rate even at the highest concentrations. Gene expression profiles ofhsp70, sod, cat, andgstgenes were analyzed by quantitative real-time PCR and defined patterns of transcription were observed. Moreover posttranscriptional analyses were also performed suggesting the impairment of metabolic functions, under strong oxidative conditions (as occurred in paralarvae exposed to Cd) or the complete detoxification events (as occurred in paralarvae exposed to Mn).
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Tajika, Amane, Naoki Morimoto, Ryoji Wani, Carole Naglik, and Christian Klug. "Intraspecific variation of phragmocone chamber volumes throughout ontogeny in the modern nautilidNautilusand the Jurassic ammoniteNormannites." PeerJ 3 (October 6, 2015): e1306. http://dx.doi.org/10.7717/peerj.1306.
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Nautilusremains of great interest to palaeontologists after a long history of actualistic comparisons and speculations on aspects of the palaeoecology of fossil cephalopods, which are otherwise impossible to assess. Although a large amount of work has been dedicated toNautilusecology, conch geometry and volumes of shell parts and chambers have been studied less frequently. In addition, although the focus on volumetric analyses for ammonites has been increasing recently with the development of computed tomographic technology, the intraspecific variation of volumetric parameters has never been examined. To investigate the intraspecific variation of the phragmocone chamber volumes throughout ontogeny, 30 specimens of RecentNautilus pompiliusand two Middle Jurassic ammonites (Normannites mitis) were reconstructed using computed tomography and grinding tomography, respectively. Both of the ontogenetic growth trajectories from the twoNormannitesdemonstrate logistic increase. However, a considerable difference inNormanniteshas been observed between their entire phragmocone volumes (cumulative chamber volumes), in spite of their similar morphology and size. Ontogenetic growth trajectories fromNautilusalso show a high variation. Sexual dimorphism appears to contribute significantly to this variation. Finally, covariation between chamber widths and volumes was examined. The results illustrate the strategic difference in chamber construction betweenNautilusandNormannites. The former genus persists to construct a certain conch shape, whereas the conch of the latter genus can change its shape flexibly under some constraints.
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Groeneveld, J. C., G. Cliff, S. F. J. Dudley, A. J. Foulis, J. Santos, and S. P. Wintner. "Population structure and biology of shortfin mako, Isurus oxyrinchus, in the south-west Indian Ocean." Marine and Freshwater Research 65, no. 12 (2014): 1045. http://dx.doi.org/10.1071/mf13341.
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The population structure, reproductive biology, age and growth, and diet of shortfin makos caught by pelagic longliners (2005–10) and bather protection nets (1978–2010) in the south-west Indian Ocean were investigated. The mean fork length (FL) of makos measured by observers on longliners targeting tuna, swordfish and sharks was similar, and decreased from east to west, with the smallest individuals occurring near the Agulhas Bank edge, June to November. Nearly all makos caught by longliners were immature, with equal sex ratio. Makos caught by bather protection nets were significantly larger, males were more frequent, and 93% of males and 55% of females were mature. Age was assessed from band counts of sectioned vertebrae, and a von Bertalanffy growth model fitted to sex-pooled length-at-age data predicted a birth size (L0) of 90 cm, maximum FL (L∞) of 285 cm and growth coefficient (k) of 0.113 y–1. Males matured at 190 cm FL, aged 7 years, and females at 250 cm, aged 15 years. Litter sizes ranged from nine to 14 pups, and the presence of gravid females in bather protection nets suggested that some pupping occurred in shelf waters. Teleosts (mainly Trachurus capensis) occurred in 84% of stomachs collected on longliners, whereas elasmobranchs (63.5%) were most common in samples collected from bather protection nets, followed by teleosts (43.1%) and cephalopods (36.5%). Larger prey size may be a factor that attracts large makos to coastal waters.
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Rice, Sean H. "The bio-geometry of mollusc shells." Paleobiology 24, no. 1 (1998): 133–49. http://dx.doi.org/10.1017/s0094837300020017.
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The shells of gastropods and cephalopods grow by production of new material, by the mantle, at the lip of the shell. I derive a model of shell form that allows us to describe the morphology of a shell in terms of independently definable biological parameters. These are (1) the relative rates of shell production at different points around the aperture, (2) the total amount of shell produced per time interval, (3) the growth rate of the aperture, (4) aperture shape, and (5) the orientation of the animal within the shell. Describing shell form in these terms allows us to see what biological changes must occur in development in order to change one shell morphology into another and what constraints are associated with particular morphological transformations. The model shows that it is developmentally easy to derive a slightly coiled limpet shell from that of a high-spired ancestor, but difficult to take the next step to a fully conical limpet. Many, if not most, real gastropod shells are not conical but rather have a convex or concave profile. I show that these forms result from a decoupling of shell production rates from the growth rate of the animal within the shell. The model also shows how truly different forms, such as vermetid snails and heteromorph ammonites, escaped the confines of spiral growth–sometimes by rotating the body within the shell, and sometimes by taking up a growth strategy that does not constrain them to coil. This model is compatible with shell morphometric models that have been widely discussed in the literature but strives toward a different goal: understanding the relationships between the various biological processes involved in shell development.
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da Silva, Thaísy Emmanuelle Florentino, Rosangela Lessa, and Francisco Marcante Santana. "Current knowledge on biology, fishing and conservation of the blue shark (Prionace glauca)." Neotropical Biology and Conservation 16, no. 1 (2021): 71–88. http://dx.doi.org/10.3897/neotropical.16.e58691.
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The blue shark (Prionace glauca) is a large predator in marine ecosystems, figuring as the most common and abundant species in oceanic fisheries. For this reason, many studies on this species were conducted throughout its entire distribution range. However, no comparison has been made regarding the variability of the aspects addressed herein. Thus, the present study aims at analyzing the available information on P. glauca. This species constitutes between 85 and 90% of the total elasmobranchs caught by oceanic fisheries with pelagic longlines. Growth parameters reveal that individuals in the Atlantic Ocean show the highest asymptotic lengths when compared to those found in other oceans. Females present an average uterine fecundity of 30 embryos. Although it shows a diverse diet, it is mainly composed of teleost fish and cephalopods. Currently, the main threat to the species is commercial fishing, being listed in Brazil and worldwide, according to IUCN as Near Threatened. Regardless, information on crucial aspects, such as its population dynamics, are still scarce or unreliable for many areas. Despite the number of studies regarding its distribution, abundance, and biology, data for new stock assessments of P. glauca are still needed to improve the species’ management.
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Rodríguez-González, Valverde, and García. "Performance of Marine Lecithin Supplemented Feeds for the Common Octopus (Octopus vulgaris) Ongrowing: Changes in Proximate Composition and Lipid Classes’ Profile." Fishes 4, no. 3 (2019): 47. http://dx.doi.org/10.3390/fishes4030047.
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The development of artificial diets is considered vital for feasible cephalopods’ culture. Octopus vulgaris need a diet with a high protein content but also lipids are important at a lower quantity, as polar lipids and LC-PUFA are essential for development during early stages. In the present study the suitability of marine lecithin as a dietary supplement for O. vulgaris juveniles’ formulated feeds was tested for 56 days, assessing the performance, changes in proximate composition, and lipid classes’ profile in the digestive gland and carcass. Sixteen octopus were fed one of two semi-moist feeds based on dry ingredients: either CALPRO (N = 4) as control or CALPRO-LM (N = 8); which differed from the first, due to the inclusion of 20 g/kg of marine lecithin as a phospholipid dietary supplement. Results showed that marine lecithin did not enhance feed intake, growth, protein or lipid incorporation, nutrients digestibility or feed efficiency. Moreover, at this level of inclusion, the composition of tissues (digestive gland and carcass) regarding macronutrients and lipid classes’ profile presented only a small amount of differences. In conclusion, the inclusion of marine lecithin did not promote beneficial effects on performance, making necessary further research related to the nutritional requirements of common octopus.
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Waite, J. N., V. N. Burkanov, and R. D. Andrews. "Prey competition between sympatric Steller sea lions (Eumetopias jubatus) and northern fur seals (Callorhinus ursinus) on Lovushki Island, Russia." Canadian Journal of Zoology 90, no. 1 (2012): 110–27. http://dx.doi.org/10.1139/z11-117.
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Approximately 1 000 Steller sea lions ( Eumetopias jubatus (Schreber, 1776); SSL) and 14 000 northern fur seals ( Callorhinus ursinus (L., 1758); NFS) breed sympatrically on Lovushki Island in the Russian Far East, creating the potential for interspecific competition for prey. An additional 13 000 – 14 000 juvenile NFS are present during the breeding season. The diets of breeding SSL and both breeding and juvenile NFS were examined through analysis of scats and spews collected during the breeding seasons of 2003, 2005, and 2007–2008. There were significant overlaps in the prey species and size selection of SSL and juvenile NFS. There were significant differences between the diets of SSL and breeding NFS. SSL and juvenile NFS fed primarily on Atka mackerel ( Pleurogrammus monopterygius (Pallas, 1810)), while breeding NFS fed on cephalopods, salmon (genus Oncorhynchus Suckley, 1861), Atka mackerel, and northern smoothtongue ( Leuroglossus schmidti Rass, 1955). The partitioning of resources between breeding animals has allowed both species to coexist within the same region and likely reflected differences in foraging abilities and provisioning strategies of the adults and the fasting abilities of their pups. However, continued growth of the NFS population may lead to the exclusion of SSL owing to interspecific competition for prey.
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Adams, Josh, John Y. Takekawa, and Harry R. Carter. "Stable foraging areas and variable chick diet in Cassin's auklets (Ptychoramphus aleuticus) off southern California." Canadian Journal of Zoology 82, no. 10 (2004): 1578–95. http://dx.doi.org/10.1139/z04-140.
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Planktivorous seabirds readily respond to changes in marine ecosystems and have the ability to integrate information regarding variability in abundance, availability, and community composition of key prey resources. We studied the foraging and breeding ecology of the Cassin's auklet, Ptychoramphus aleuticus (Pallas, 1811), off southern California during three breeding seasons (1999–2001), when large intra- and inter-annual variability occurred in local oceanographic conditions during a prolonged La Niña event. Radio-marked parents used consistent core foraging areas within 30 km of their colony, aggregated in shelf waters (<200 m depth), and occasionally foraged in deeper waters. Parents delivered primarily euphausiids, pelagic larval-juvenile fishes, and minor amounts of cephalopods and other crustaceans. Whereas the euphausiid Thysanoessa spinifera Holmes, 1900 was most important during 1999 and 2001, Euphausia pacifica Hansen, 1911 replaced adult T. spinifera in 2000 after an anomalous eastward inflection of the California Current occurred near the auklets' foraging area. Differences in chick diets, however, did not significantly influence fledging success and growth among first chicks, but the proportion of pairs successfully fledging an alpha chick and initiating a second clutch was exceptional in 1999 (63%) and 2000 (75%), and less in 2001 (7%). We suggest that dietary composition was influenced by modified prey availability driven in part by fluctuations in regional upwelling and circulation.
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Lacoue-Labarthe, T., S. Martin, F. Oberhänsli, et al. "Effects of increased <i>p</i>CO<sub>2</sub> and temperature on trace element (Ag, Cd and Zn) bioaccumulation in the eggs of the common cuttlefish, <i>Sepia officinalis</i>." Biogeosciences Discussions 6, no. 3 (2009): 4865–94. http://dx.doi.org/10.5194/bgd-6-4865-2009.
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Abstract. Cephalopods play a key role in many marine trophic networks and constitute alternative fisheries resources, especially given the ongoing decline in finfish stocks. Along the European coast, the eggs of the cuttlefish Sepia officinalis are characterized by an increasing permeability of the eggshell during development, which leads to selective accumulation of essential and non-essential elements in the embryo. Temperature and pH are two critical factors that affect the metabolism of marine organisms in the coastal shallow waters. In this study, we are testing the effects of pH and temperature through a crossed (3×2) laboratory experiment. Seawater pH showed a strong effect on the egg weight and non-significant impact on the hatchlings weight at the end of development implying egg swelling process and embryo growth disturbances. The lower pH of incubation seawater of eggs, the more the hatchlings accumulated 110m Ag in their tissues. The 109Cd CF decreased with increasing pH and 65Zn CF reached the maximal values pH 7.85, independent of temperature. Our results suggest that pH and temperature affected both the permeability properties of the eggshell and the embryo metabolism. To the best of our knowledge, this is one of the first studies on the ocean acidification and ocean warming consequences on the metal uptake in marine organisms, stimulating further interest to evaluate the likely ecotoxicological impact of the global change on the early-life stage of the cuttlefish.
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Landing, Ed, Jonathan B. Antcliffe, Martin D. Brasier, and Adam B. English. "Distinguishing Earth’s oldest known bryozoan (Pywackia, late Cambrian) from pennatulacean octocorals (Mesozoic–Recent)." Journal of Paleontology 89, no. 2 (2015): 292–317. http://dx.doi.org/10.1017/jpa.2014.26.
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AbstractBryozoans and all biomineralized metazoan phyla extend back into the Cambrian.PywackiaLanding, 2010 is confirmed as a secondarily phosphatized, late Cambrian stenolaemate bryozoan with colonial habit; mineralized zooarium (originally calcareous); granular/rarely granular-prismatic histology of its trilamellar walls; and polymorphism shown by deep autozooecia with diaphragms and hemiphragms, axial zooecia with diaphragms, and probable nanozooecia. The irregular form ofPywackiareflects growth as a 14-hedron that could not branch and a lack of structures such as thickened walls or styles that maintain regular autozooecial spacing in later stenolaemates.Pywackiais a stem group stenolaemate with a stolon modified into a budding axial zooid and autozooid budding. It is morphologically simpler than the highly evolved late Tremadocian bryozoans of South China with features such as styles, cystiphragms, thickened zooecial walls, and massive or branching colonies. As with some bryozoans,Pywackialacks holdfasts but has lineated living chambers and variably sized autozooecia. The late Cambrian origin of bryozoans, euconodonts, polyplacophorans, and cephalopods set the stage for the Ordovician Radiation’s complex communities.Pywackiais not a pennatulacean octocoral. It lacks both a pennatulacean axial rod histology and a budding zooid that remains confluent with daughter autozooids. Indeed,Pywackiawalled off its axial zooid. Similarity of the 6- and 12-sidedPywackiazooarium with circular to 4-sided pennatulacean axes only includes calcareous composition and the general shapes ofPywackiazooaria and someLituariaaxial rods. The pennatulacean record does not extend from the Mesozoic into the Cambrian, and early cnidarians were not phosphatic. The diagnosis ofPywackiais modified.
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Hoving, Hendrik Jan T., Marek R. Lipiński, and Lammertjan Dam. "The male reproductive strategy of a deep-sea squid: sperm allocation, continuous production, and long-term storage of spermatophores in Histioteuthis miranda." ICES Journal of Marine Science 67, no. 7 (2010): 1478–86. http://dx.doi.org/10.1093/icesjms/fsq041.
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Abstract Hoving, H. J. T., Lipiński, M. R., and Dam, L. 2010. The male reproductive strategy of a deep-sea squid: sperm allocation, continuous production, and long-term storage of spermatophores in Histioteuthis miranda. – ICES Journal of Marine Science, 67: 1478–1486. Squid are semelparous organisms. Much of what we know about squid reproduction relates to females, because few studies have addressed males and, although males are similarly challenged by semelparity, it remains virtually unknown what tactics squid have evolved to allocate sperm to spermatophores. The male reproductive strategy of the deep-sea squid Histioteuthis miranda was examined by describing the male reproductive anatomy, which appears unique among cephalopods, and by quantifying spermatophore production and sperm allocation. The species produces and stores spermatophores over a considerable period of continuous somatic growth. Body size and spermatophore length (SpL) are positively correlated, and the size difference between spermatophores stored by a single individual was up to 270%. Individuals had between 136 and 2276 spermatophores inside their reproductive system, and spermatophores may be stored for as long as 4.5 months. The relationship between SpL and the mass of sperm per spermatophore was polynomial, demonstrating that larger spermatophores did not necessarily contain more sperm. The unique male morphology and the continuous production and long-term storage of spermatophores in H. miranda seem to allow the species to increase the window in which reproduction can take place, a strategy that may be valuable in the deep-sea environment.
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Shea, Elizabeth K., and Michael Vecchione. "Ontogenic changes in diel vertical migration patterns compared with known allometric changes in three mesopelagic squid species suggest an expanded definition of a paralarva." ICES Journal of Marine Science 67, no. 7 (2010): 1436–43. http://dx.doi.org/10.1093/icesjms/fsq104.
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Abstract Shea, E. K., and Vecchione, M. 2010. Ontogenic changes in diel vertical migration patterns compared with known allometric changes in three mesopelagic squid species suggest an expanded definition of a paralarva. – ICES Journal of Marine Science, 67: 1436–1443. Planktonic and newly hatched cephalopods are routinely called paralarvae. Currently, the onset of diel vertical migration (DVM) marks the end of the paralarval phase, although changes in ontogenic growth trajectories may also be used. Patterns of DVM are reported for the first time for three poorly understood mesopelagic squid species. Discrete-depth samples taken during the Amsterdam Mid North Atlantic Plankton Expeditions (AMNAPE) of 1980–1983 are used to examine the timing of ecological and morphological changes in Chtenopteryx sicula, Mastigoteuthis magna, and Brachioteuthis sp. 3. DVM patterns are species-specific, and ontogenic changes in DVM coincide with allometric changes in the arm, fin, and funnel characters of C. sicula at 7 mm mantle length. Mastigoteuthis magna is not concentrated in the upper 250 m of the water column during the day, and no clear DVM pattern is found in Brachioteuthis sp. 3, meaning that the endpoint of the paralarval phase cannot be defined ecologically in these species. Other ecological transformations, e.g. changes in prey-capture ability, are therefore explored as alternatives to DVM. The pad-shaped club and long neck are proposed as visual markers of the end of the paralarval phase of C. sicula and Brachioteuthis sp. 3, respectively.
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Lacoue-Labarthe, T., S. Martin, F. Oberhänsli, et al. "Effects of increased <i>p</i>CO<sub>2</sub> and temperature on trace element (Ag, Cd and Zn) bioaccumulation in the eggs of the common cuttlefish, <i>Sepia officinalis</i>." Biogeosciences 6, no. 11 (2009): 2561–73. http://dx.doi.org/10.5194/bg-6-2561-2009.
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Abstract. Cephalopods play a key role in many marine trophic networks and constitute alternative fisheries resources, especially given the ongoing decline in finfish stocks. Along the European coast, the eggs of the cuttlefish Sepia officinalis are characterized by an increasing permeability of the eggshell during development, which leads to selective accumulation of essential and non-essential elements in the embryo. Temperature and pH are two critical factors that affect the metabolism of marine organisms in the coastal shallow waters. In this study, we investigated the effects of pH and temperature through a crossed (3×2; pH 8.1 (pCO2, 400 ppm), 7.85 (900 ppm) and 7.6 (1400 ppm) at 16 and 19°C, respectively) laboratory experiment. Seawater pH showed a strong effect on the egg weight and non-significant impact on the weight of hatchlings at the end of development implying an egg swelling process and embryo growth disturbances. The lower the seawater pH, the more 110 mAg was accumulated in the tissues of hatchlings. The 109Cd concentration factor (CF) decreased with decreasing pH and 65Zn CF reached maximal values pH 7.85, independently of temperature. Our results suggest that pH and temperature affected both the permeability properties of the eggshell and embryonic metabolism. To the best of our knowledge, this is one of the first studies on the consequences of ocean acidification and ocean warming on metal uptake in marine organisms, and our results indicate the need to further evaluate the likely ecotoxicological impact of the global change on the early-life stages of the cuttlefish.
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Gao, Chunxia, Siquan Tian, Richard Kindong, and Xiaojie Dai. "Biology and Environmental Preferences of Wahoo, Acanthocybium solandri (Cuvier, 1832), in the Western and Central Pacific Ocean (WCPO)." Journal of Marine Science and Engineering 8, no. 3 (2020): 184. http://dx.doi.org/10.3390/jmse8030184.
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Wahoo Acanthocybium solandri is a common bycatch pelagic species in oceanic fisheries targeting tuna and tuna-like species. Biology and environmental preferences are important parameters in understanding life history of fish species including wahoo. Despite the socio-economic importance of wahoo in many coastal countries, little is known about their biological and fisheries information in the Western and Central Pacific Ocean (WCPO). These parameters were analyzed on the basis of samples collected via the Chinese tuna long-line Fishery Observer Programme in 2012. Results obtained from this study show that the fork length (FL) of wahoo ranged from 59 to 169 cm with an average of 111.3 cm, and two dominant size groups were identified at 100 to 130 cm for males and 90 to 130 cm for females. Body size did not significantly differ between female and male wahoo specimens. Wahoo specimens expressed a positive allometric growth (b = 3.183), and the sex ratio was 1.9:1 (female/male), which differed significantly between both sexes. Only female wahoo were observed in catches of FL > 150 cm. The estimated lengths at 50% maturity (FL50) of female and male wahoo were 84 cm and 83 cm, respectively. Gonadosomatic index (GSI) of wahoo was at its peak in November, and on the basis of the stomach content analysis, wahoo mainly preyed on fish (84.64%), cephalopods (14.26%), and crustaceans (1.1%), found on the basis of prey number. The optimal swimming depth and water temperature of wahoo in the WCPO were found to range between 70 and 110 m and 23.1 and 24 °C, respectively. The updated life history information presented in this work helps to address current data limitations and provides critical information for future assessments of wahoo stocks in the WCPO.
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Barroso-Barcenilla, Fernando, María José Comas-Rengifo, Luís Vítor Duarte, Antonio Goy, and Gemma Martínez. "A new genus of nautiloid in the Toarcian of the Iberian peninsula (Spain and Portugal)." Bulletin de la Société Géologique de France 182, no. 5 (2011): 391–404. http://dx.doi.org/10.2113/gssgfbull.182.5.391.
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Abstract Historically, most of the nautiloids arisen during the Early Jurassic have been assigned initially to the genus NautilusLinnaeus, 1758, and subsequently to CenocerasHyatt, 1884. At present, a tendency to rehabilitate other genera or to describe new ones predominates among the few authors who try to classify and to group these problematic cephalopods. In the present work, the new genus Ligeiceras has been described for remarkably small and involute nautiloids with notably retrogressive suture lines. It has a smooth or slightly ornamented external surface, limited to thin tenuous, ventraly retroverse and distant growth lines and longitudinal and transversal striae. This group, seemingly, appeared after the biotic crisis of the end of the Tenuicostatum/Polymorphum Zone, evolved during the radiation of the Early Toarcian Serpentinum/Levisoni Zone and the Late Toarcian, and survived at least until the Aalenian. New specimens from the Iberian peninsula (Basque-Cantabrian and Iberian basins, Spain; and Lusitanian basin, Portugal), belonging to the taxa Nautilus fournetiDumortier, 1874 (selected as type species), Nautilus inornatusd’Orbigny, 1843, Nautilus anomphalusPia, 1914, Nautilus jurensisQuenstedt, 1846-49, and, with doubts, Cenoceras globulusRulleau, 2008, have been collected, described and assigned to this systematic group. Although some of these species have already been cited in the literature, Ligeiceras fourneti, Ligeiceras jurensis and Ligeiceras? globulus have never been previously clearly described or illustrated, and their stratigraphic distribution has not been determined accurately for the Iberian peninsula, as has been done here for these taxa and for Ligeiceras inornatus and Ligeiceras anomphalus. Therefore, the present work on the new genus Ligeiceras constitutes a notable advance in the knowledge of these nautiloids, and seems to confirm that the dwarfism could have been a relatively generalized tendency in the Upper Toarcian of southwestern Europe, possibly due to palaeoenvironmental causes.
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Villanueva, R. "Diet and mandibular growth ofOctopus magnificus(Cephalopoda)." South African Journal of Marine Science 13, no. 1 (1993): 121–26. http://dx.doi.org/10.2989/025776193784287239.
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Cortez, Tito, Angel F. González, and Angel Guerra. "Growth of cultured Octopus mimus (Cephalopoda, Octopodidae)." Fisheries Research 40, no. 1 (1999): 81–89. http://dx.doi.org/10.1016/s0165-7836(98)00203-3.
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