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Academic literature on the topic 'Cephalopods growth'
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Journal articles on the topic "Cephalopods growth"
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.
Full textAbstract:
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.
Full textAbstract:
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.
7
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.
8
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.
9
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.
Full textAbstract:
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