New papers on cephalopods

Discussion in 'Physiology and Biology' started by Steve O'Shea, Apr 13, 2004.

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  1. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    I thought I'd post something here, and lock the thread from further posts, to draw attention to some rather interesting papers/publications on cephalopods that are coming out.

    By no means will this ever be an exhaustive list; it will just be the abstracts and references to works that I stumble upon as I go about my thing (and likewise, stuff people send me).

    The first one, here on Nautilus.

    Bonnaud L, Ozouf-Costaz C, Boucher-Rodoni, R. 2004. A molecular and karyological approach to the taxonomy of Nautilus. COMPTES RENDUS BIOLOGIES, 327 (2): 133-138.

    Abstract:
    Nautiloids, the externally shelled cephalopods of Cambrian origin, are the most ancient lineage among extant cephalopods. Their ancestral characters are explored based on morphological and molecular data (18S rDNA sequence) to investigate the evolution of present cephalopod lineages. Among molluscs, nautilus 18S rDNA gene is the longest reported so far, due to large nucleotidic insertions. By comparison with other 18S sequences, the complete gene of N. macromphalus helps to clarify the taxonomic status of, the three universally recognised Nautilus species. The range of interspecific molecular differences supports separation of the present species into two surviving ectocochleate genera, Nautilus and Allonautilus. Nautiloid 18S is considered as corresponding to the ancestral form of 18S as is the number of chromosomes in Nautilus (52), the lowest among cephalopods. Comparison of karyological characteristics amongst cephalopods in a phylogenetic context suggests a possible correlation between duplication events and lineage divergence. (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.
     
  2. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    Here's another:

    Landman, N.H.; Cochran, J.K.; Cerrato, R.; Mak, J.; Roper, C.F.E.; Lu, C.C. 2004. Habitat and age of the giant squid (Architeuthis sanctipauli) inferred from isotopic analyses. Marine Biology 144(4): 685-691.

    Abstract
    The age and habitat of the giant squid, Architeuthis sanctipauli Velain, 1877, were determined based on isotopic analyses of the statoliths of three female specimens captured off Tasmania, Australia, between January and March 1996. Assuming that the aragonite of the statoliths formed in equilibrium with seawater, 18O analyses indicated that the squid lived at temperatures of 10.5–12.9°C, corresponding to average depths of 125–250 m and maximum depths of 500 m. The capture records indicated that these squid may have occasionally ranged still deeper, to as much as 1000 m. All the statoliths were labeled with bomb 14C (14C=+22.9 to +44.6), consistent with the depths inferred from 18O. A thin section through one of the statoliths revealed 351 growth increments grouped into check-ring structures every 10–16 increments. A model for statolith growth and the pattern of temporal change in 14C in the water column was used to estimate the ages of the three specimens. These estimates were very sensitive to the choice of depth range over which 14C values were integrated. Assuming that the capture depths represented the maximum habitat depths of these individuals, the calculations suggested an age of 14 years or less. More refined age estimates require a better understanding of the variation of 14C and temperature with depth in the areas in which the squids live.
    ........
    I can't get all of the symbols in there (triangles, isotopes of carbon etc.; sorry); Someone who knows something about this might be able to interpret it better.
     
  3. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    Tissue distribution of the amnesic shellfish toxin, domoic acid, in Octopus vulgaris from the Portuguese coast

    Authors: Costa, P.R.; Rosa, R.; Sampayo, M.A.M., 2004

    Source: MARINE BIOLOGY, 144 (5): 971-976

    Abstract:
    Domoic acid (DA), the amnesic shellfish toxin, is a food-web-transferred algal toxin that has been detected in many marine organisms from copepods to whales. However, cephalopods, which are important members of the food chain, have never been implicated in DA transfer or accumulation. Here, we present data showing relevant values of DA detected in the common octopus (Octopus vulgaris) from the Portuguese continental coast. Even though DA is hydrophilic and is not expected to be accumulated in the tissues, DA was always detected in our octopus tissue samples. Tissue distribution of DA revealed that the digestive gland and the branchial hearts are the main organs of DA accumulation. Highly variable DA concentrations, ranging from 1.1 to 166.2 mug DA g(-1), were observed in the digestive glands. Low levels of DA were detected in the digestive tract (stomach and intestine) and could be a consequence of high digestion rates or a result of non-exposure to toxic vectors during the sampling period. In fact, octopus prey, such as bivalves, crustaceans and fishes, are known to occasionally work as DA vectors. Consequently, DA uptake into octopus tissues is likely sporadic. Similar low levels were detected in the kidney, gills, systemic heart, posterior salivary glands and mantle, and no DA was found in either the gonads or the ink sac. These data are the necessary first step towards achieving an understanding of the accumulation of phycotoxins in O. vulgaris.
     
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    Egg masses of Loligo opalescens (Cephalopoda : Myopsida) in Monterey Bay, California following the El Nino event of 1997-1998

    Authors: Zeidberg, LD; Hamner, W; Moorehead, K; Kristof, E

    Source: BULLETIN OF MARINE SCIENCE, 74 (1): 129-141 JAN 2004

    Abstract:
    The commercial fishery for Loligo opalescens (Berry 1911) off the coast of California collapsed in 1998 following the 1997 El Nino event. Nonetheless, small schools of adult squid in non-commercial quantities routinely were attracted to night-lights below boats anchored near Monterey Harbor. Accordingly, Monterey Bay was searched for egg beds with sonar, an ROV, and with SCUBA during September and October 1998 to see if adults were spawning. Scattered egg masses were found with brown capsules in the center surrounded by more recently deposited white capsules with embryonic developmental differences of at least eight days. Brown capsules may provide visual stimulus for repeated site-specific spawning, 'hotspot' lek behavior. The egg masses were composed of multiple cohorts with capsule dimensions highly correlated to developmental stage. Means of 164 (SD = 20, n = 193) eggs/capsule and 259 (SD = 212, n = 13) capsules/mass were found, with 152 egg masses in the most concentrated 1000 m(2) of the egg bed. The expected number of eggs was 6.46 x 10(6) for this 1000 m(2). The sea star Asterina miniata (Brandt, 1835) was observed feeding on the egg masses 26 times in Monterey Bay. In the laboratory the A. miniata and the gastropods Kelletia kelletii (Forbes, 1850) and Cypraea spadicea (Swainson, 1836) ate Loligo eggs.
     
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    Steera, M.A.; Moltschaniwskyj, N.A.; Nichols, D.S.; Miller, M. 2004. The role of temperature and maternal ration in embryo survival: using the dumpling squid Euprymna tasmanica as a model. Journal of Experimental Marine Biology and Ecology 307: 73– 89.

    Abstract
    Using a ‘model’ sepiolid, Euprymna tasmanica, this study investigated the role of maternal nutritional and thermal history on egg quality and subsequent embryo survival. E. tasmanica is a multiple spawner, therefore it was possible to track egg quality and hatching success over successive spawning episodes. A two-factor orthogonal experimental design, involving two feeding levels (high and low rations) and two temperatures (summer and winter), was implemented with half of the replicates used to explore embryonic development and the remaining half examining egg-yolk quality via fatty acid analysis. Differences in reproductive output and embryo mortality were largely attributed to maternal ration and not temperature. Females maintained on low ration produced smaller clutches, consisting of smaller eggs and exhibiting higher embryo mortality rates than high ration females. Both batch fecundity and relative hatching success declined over successive clutches. Lipid content was also significantly lower in low ration females, however, the relative quality in terms of lipid and fatty acid constituents was maintained regardless of treatment and spawning frequency. It is suggested that elevated embryo mortality rate in eggs spawned by low-fed females was a function of insufficient maternally derived yolk resources to fuel embryogenesis. Results indicate that maternal nutritional and reproductive history are important determinates for offspring survival, potentially having significant effects on the magnitude of subsequent recruitment events in squid populations.
     
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    Jackson, G.D.; Jackson, C.H. 2004. Mating and spermatophore placement in the onychoteuthid squid Moroteuthis ingens. Journal of the Marine Biological Association of the United Kingdom 84: 783-784.

    Abstract
    Males of the onychoteuthid squid Moroteuthis ingens implant spermatophores directly into a variety of internal and external tissues of the female, based on the examination of 14 individuals collected south of Tasmania, Australia. Furthermore, the capture of a pair of mating individuals suggests that ‘jaw locking’ reminiscent of cichlid fish may be a behaviour associated with courtship and mating.
     
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    Kasugai, T.; Shigeno, S.; Ikeda, Y. 2004. Feeding and external digestion in the Japanese Pygmy Squid Idiosepius paradoxus (CEPHALOPODA: IDIOSEPIIDAE). Journal of Molluscan Studies 70: 231-236.


    ABSTRACT
    The ingestion of shrimps and fish in the Japanese pygmy squid Idiosepius paradoxus was examined. Idiosepius paradoxus paralysed shrimps within 1 min of seizure, extended the buccal mass into the exoskeleton of the shrimp without any biting action, and ingested the flesh. During ingestion of the shrimp flesh, the squids moved their beaks inside the buccal mass, but did not bite into the internal flesh. Idiosepius paradoxus appears to use external digestion by injecting digestive enzymes into the flesh and sucking up semi-digested flesh. The exoskeleton of the shrimp was never chipped or eaten, and the discarded remains of the shrimp contained virtually no flesh, resembling a moult with completely empty appendages. Idiosepius paradoxus was unable to paralyse captured fish. In the case of large fish, the squids left them or only partly ingested them. In the case of small fish, I. paradoxus held them within the arm crown after seizure. From a close inspection of discarded remains after feeding, it appeared that the bones of fish were not destroyed, but only the muscle had disappeared. When I. paradoxus fed on small fish, the discarded remains were intact body skeletons. The outer lip of I. paradoxus possesses a unique organ, the ‘lip gland’ that consists of goblet glandular cells. It seems likely that this organ produces a mucous secretion and appears to assist in external digestion.
     
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