A novel statistical analysis of cnidocysts in acontiarian sea anemones (Cnidaria, Actiniaria) using generalized linear models with gamma errors

Comparative studies on cnidocysts, involving adequate statistical treatment, are very scarce. Classical statistical tests are frequently used assuming normal frequency distributions of capsule lengths, but many distributions are non-normal in acontiarian sea anemones. A traditional choice in these situations are non-parametric tests, although they are not as powerful as parametric tests. An extension of classical methods was developed by some authors; these models, called Generalized Linear Models (GLM), can be used under certain conditions with non-normal data. In view of the properties of our data, that are positive, skewed and with constant coefficient of variation, a GLM with gamma distribution and inverse link function was chosen to analyse the cnidae of acontia from the species Haliplanella lineata, Tricnidactis errans and Anthothoe chilensis. Graphical analysis of residuals showed that these assumptions were reasonable. This method allowed us to avoid transformation of data set and controversial cases in the limit of significance level. For this task, appropriate subroutines in GLIM language were written. In all cases highly significant differences were found between the specimens considered for every species and nematocyst type (b-rhabdoids, p-rhabdoids B1b and p-rhabdoids B2a).     

Polypeptide cytolytic toxins from sea anemones (Actiniaria)

Abstract Biochemical and biological properties of 30 cytolytic polypeptide toxins isolated from 18 species of sea anemones ( Actiniaria ) are presented and classified into three groups according to their molecular mass, isoelectric points and the molecular mechanism of action. Phospholipase A₂-like toxins (30 kDa) from Aiptasia pallida are dissimilar to acidic metridiolysin (80 kDa) from Metridium senile and the group of about 27 predominantly basic toxins, having a molecular mass of 16–20 or 10 kDa, inhibited by sphingomyelin. They are lethal for both invertebrates and vertebrates, cardiotoxic, cutolytic and cytotoxic. Pharmacological activities, cytotoxic and cytolytic properties are mediated, at least in part, by forming pores in lipid membranes. Channels, 1–2 nm in diameter, formed in planar lipid membranes are cation selective and rectified. The mechanisms and some characteristics of ion channel formation by the toxins in the cells as well as in artificial lipid membranes are summarized and discussed in view of the structure-function studies of the toxins. Putative biological roles of toxins, based on their channel-forming activity, in the capture and killing of prey, digestion, repelling of predators and intraspecific spatial competition are suggested.     

Nematocysts of sea anemones (Actiniaria,Ceriantharia and Corallimorpharia: Cnidaria): nomenclature

A brief historical review of nematocyst terminology is given and three nomenclatural problems are discussed. It is proposed to combine the terms initiated by Weill (1934) with those of Schmidt (1969). A new mesobasic grade, intermediate between microbasic and macrobasic is proposed for amastigophores and p-mastigophores possessing a short Faltstück. A more liberal interpretation of Weill's (1934) terminology for nematocysts than that proposed by Cutress (1955) is suggested in respect of microbasic amastigophores and p-mastigophores. Basitrichs and b-mastigophores continue to be recognized as separate categories.deceased     

Features of biology of the sea anemone Charisea saxicola Torrey, 1902 (Actiniaria: Condylanthidae) from the northwest Pacific

The first data on features of the biology of the sea anemone Charisea saxicola, which is widespread in the Northwest Pacific, were obtained. That species, inhabiting the littoral of Shikotan Isl. (the Minor Kurile Ridge), belongs by its trophological attributes to nonselective deposit feeders. Animals swallow soil together with the organisms in it, not separating mineral particles from organic ones. Populations of Ch. saxicola are presented by individuals of mail and female sex, however the females prevailed in number. Hermaphrodites and evidence of sex change were not revealed in that species. Females were in the postspawning condition in all settlements. Spermatogenic cells of the new generation at two stages of development were recorded in males.     

An extremely thermophilic Methanococcus from a deep sea hydrothermal vent and its plasmid

An extremely thermophilic methanogen was isolated from a hydrothermal vent core sample from Guaymas Basin, Gulf of California, at a depth of 2003 m. The isolate, designated strain AG86, was a coccoid autotroph using H₂-CO₂ as energy and carbon source with a growth temperature range of 48 to 92°C, optimum, 85°C. AG86 required NaCl and Mg²⁺ and trace amounts of selenite and tungstate. Vitamins were not required. However, yeast extract, Casamino acids and Trypticase stimulated growth significantly. When grown in the presence of these stimulants and at the optimal growth temperature and pH 6.5, the minimum doubling time was 20 min. Cells were fragile and readily lysed by detergents. The mol% G+C was 33%. These results and partial 16S rRNA sequencing indicated that AG86 belonged to the genus Methanococcus and closely resembled Methanococcus jannaschii. Tests for extrachromosomal DNA revealed a plasmid in AG86 and two plasmids in M. jannaschii. Different patterns were obtained from restriction endonuclease digestion of the three plasmids, and no homology was observed with DNA-DNA hybridization.Abbreviations CCC DNA covalently close circular DNA - DM defined marine medium - G+C Guanine plus cytosine - MPN most probable number     

Kunitz-type protease inhibitors from acrorhagi of three species of sea anemones

Sea anemones are rich in biologically active polypeptides such as toxins and protease inhibitors. These polypeptides have so far been isolated from whole bodies, tentacles or secreted mucus. Recently, two novel peptide toxins with crab lethality have been isolated from acrorhagi (specialized aggressive organs elaborated by only certain species of sea anemones belonging to the family Actiniidae) of Actinia equina. This prompted us to survey biologically active polypeptides in the acrorhagi of two species of sea anemones, Anthopleura aff. xanthogrammica and Anthopleura fuscoviridis. No potent crab lethality was displayed by the acrorhagial extracts of both species. However, significantly high protease inhibitory activity was instead detected in the acrorhagial extracts of the two species and also in that of A. equina. From the acrorhagi of A. equina, A. aff. xanthogrammica and A. fuscoviridis, one (AEAPI), one (AXAPI) and two (AFAPI-I and AFAPI-III) protease inhibitors were isolated, respectively. The complete amino acid sequences of the four inhibitors were elucidated by N-terminal sequencing and sequencing of the C-terminal peptide fragment produced upon asparaginylendopeptidase digestion. The determined amino acid sequences revealed that all the four inhibitors are new members of the Kunitz-type protease inhibitor family.     

Prodigies of propagation: the many modes of clonal replication in boloceroidid sea anemones (Cnidaria,Anthozoa, Actiniaria)

Summary

Diverse modes of clonal propagation were documented in tiny zooxanthellate sea anemones from the tropical Pacific. All were boloceroidids, as indicated by the tentacles' basal sphincter and the animals' swimming behavior. In one species, single tentacles were pinched off at the sphincter, shed into the coelenteron, and brooded there while regenerating into minute new polyps in ~4 days. Within a day of release, the propagules fed on live prey and swam by lashing the tentacles. A similar process occurs in another species studied, Bunodeopsis medusoides. In a third species a previously undescribed mode of replication was seen. These anemones bore a primary cycle of tentacles that engaged actively in feeding and swimming, were not shed, and showed no sign of producing polyps. Alternating with these tentacles were fan-like clusters of shorter tentacles that were relatively inactive in feeding and swimming. Despite the sphincter at the base of each of these clustered tentacles, they were never shed singly; instead, each cluster separated as a unit that then regenerated into a new polyp. Two other replicative modes were observed in similar, minute boloceroidid anemones collected together in the same habitat: longitudinal fission, not previously reported in boloceroidids, and pedal scission. Modes of replication in these actinians are more diverse than once thought, but the selective forces behind this variation are so far unexplored. These prolific anemones may regularly be taking advantage of their combination of swimming and regenerative abilities to achieve dispersal, not only by sexually produced larvae, but also by cloned polyps.     

Growth, reproduction and survival of a tropical sea anemone (Actiniaria): benefits of hosting anemonefish

The ecological performance of the sea anemone Heteractis magnifica was examined during a 36-month experiment with respect to season and the presence and numbers of a mutualist (orange-fin anemonefish Amphiprion chrysopterus). Anemones primarily grew during the autumn, with most asexual reproduction occurring in winter; mortality was not strongly seasonal. Individual growth rates did not differ between anemones harboring one or two anemonefish, but these rates were three times faster than for anemones lacking Amphiprion. Anemones with two anemonefish had the highest fission rate, whereas those without anemonefish had the lowest. By contrast, anemones that were not defended by anemonefish suffered higher-than-expected mortality. As a consequence, anemones with two Amphiprion had the greatest net increase in surface area, and those lacking anemonefish had a negligible gain that was statistically indistinguishable from zero after three years. Anemonefish not only enhanced anemone survivorship as previously believed, they also fostered faster growth and more frequent asexual reproduction.     

Distribution of sea anemones (Cnidaria,Actiniaria) in Korea analyzed by environmental clustering

Hydrobiologia - Using environmental data and the geospatial clustering tools LOICZView and DISCO, we empirically tested the postulated existence and boundaries of four biogeographic regions in the...     

Chitinase gene diversity at a deep sea station of the east Pacific nodule province

The Pacific nodule province covered about 4.5 million km² in the east tropical Pacific with an abundance of polymetallic nodules at the seafloor. In view of the environmental protection and resource preservation, the survey of biodiversity was important during the reconnaissance and exploitation in this area. As one of the important component of the deep sea ecosystem, the microbial community in the Pacific nodule province was still largely unknown. The chitinolytic bacteria diversity in deep-sea sediment of a station within the Pacific nodule province was examined by molecular technology. A total of 18 chitinase genes were detected by a set of degenerate PCR primer specific for chiA gene fragment of family 18 chitinase. Most of them belonged to the Serratia-like chitinase. Eight genes had different amino acid sequences in the conserved motif, encompassing the catalytic site among the ChiA protein of family 18 glycosyl hydrolases, and clustered in an independent clade on the phylygenetic tree.     

Toward a natural classification: phylogeny of acontiate sea anemones (Cnidaria,Anthozoa, Actiniaria)

Acontia—nematocyst‐dense, thread‐like extensions of the mesenterial filaments―are the characteristic feature of the actiniarian group Acontiaria. Phylogenetic analyses have shown that acontiate taxa form a clade that also includes some taxa without acontia. We analyse five molecular markers from 85 actiniarians to explore the phylogenetic relationships among families in Acontiaria, including acontiate species assigned to other higher taxa and species without acontia that have been allied to Acontiaria. Based on our results, we redefine the group to accommodate those lineages that have lost acontia, and formalize it as superfamily Metridioidea. Based on stable and well supported clades, we resurrect Phelliidae and Amphianthidae, redefine Kadosactinidae and Actinoscyphiidae, and move two species to new genera: that previously termed Sagartiogeton erythraios belongs in Jasonactis gen. nov.; and that previously termed Anthosactis pearseae belongs in Ostiactis gen. nov., type genus of Ostiactinidae fam. nov. We also synonymized Halcampoididae and Halcampidae (as Halcampidae) and Andvakiidae and Isophelliidae (as Andvakiidae). The results of our phylogenetic analyses indicate that the diagnostic morphological characters used in the family‐level taxonomy of acontiate actiniarians such as the nematocysts of the acontia, the marginal sphincter muscle, and mesenteries divisible into macro‐ and micro‐cnemes, have to be revisited, as these features are highly homoplasious.     

Fissuroderes, a new genus of Kinorhyncha (Cyclorhagida) from the deep sea and continental shelf of New Zealand and from the continental shelf of Costa Rica

Specimens of Kinorhyncha collected by RV Sonne from the continental shelf off the coast of Costa Rica and from the deep sea East of New Zealand as well as by RV Kaharoa in the Firth of Thames are identified as five new species of a new genus Fissuroderes gen. nov. which is distinguished from all other kinorhynch genera by a ring-like cuticle in the first trunk segment and a cuticle with midventral and lateral articulations resulting in two sternal plates and one tergal plate in segments 2-10. Fissuroderes higginsi sp. nov. can be distinguished from all other species of Fissuroderes by a laterodorsal spine in segment 2 and the lack of a lateroventral spine in segment 8. Fissuroderes rangi sp. nov. is recognized from all other species by the lack of a ventrolateral spine in segment 2, the lack of a lateroventral spine in segment 5, an extremely elongate spinose tergal extension of segment 11 and a prominent midventral spinose process of the sternal plates in segment 11. Fissuroderes papai sp. nov. is identified by the short spinose process of the sternal plate of segment 11. Only Fissuroderes thermoi sp. nov. possesses bilobed sternal plates in segment 11 and a short conical tergal extension. Fissuroderes novaezealandia sp. nov. differs from F. higginsi sp. nov. in the lack of a laterodorsal spine in segment 2, the lack of an accessory spine in a lateral position in segment 8, the lack of a sublateral spine in segment 10, the existence of a lateroventral spine in segment 8 and in the lack of a subdorsal type 2-gland cell outlet in segment 2. The former species differs from F. papai sp. nov. in the lack of a lateroventral spine in segment 8, the lack of longitudinal indentations in the posterior part of the trunk cuticle of each segment and in the existence of an elongate spinose tergal extension of segment 11 and of many fine hairs on the surface of the cuticle. Fissuroderes is included into the Echinoderidae which is suggested to enclose also the genera Echinoderes and Cephalorhyncha. Echinoderes nybakkeni Higgins, 1988 is now combined as Cephalorhyncha nybakkeni (Higgins, 1988) comb. nov.     

Patterns of Symbiodinium spp. associations within the family Aiptasiidae,a monophyletic lineage of symbiotic of sea anemones (Cnidaria,Actiniaria)

Coral Reefs - Although the symbiotic relationships between dinoflagellates and cnidarians are well recognized, few studies have examined these associations from an evolutionary perspective. This is...     

Hansenomysis anaramosae n. sp., a new suprabenthic mysid (Crustacea: Mysidacea: Petalophthalmidae) from the Bellingshausen Sea (Southern Ocean)

A new petalophthalmid mysid, Hansenomysis anaramosae n. sp., is described from specimens sampled with a suprabenthic sled in the Bellingshausen Sea (Southern Ocean). Hansenomysis anaramosae is clearly distinguishable from its closest congener, H. angusticauda Tattersall, by the carapace sculpturing, the rostrum produced into a spine-like process, the shape and armature of the antennal scale, eyeplate, and telson. This new species is the fourth Hansenomysis species described from the Southern Ocean. A key to these Antarctic species is presented.     

Copepods in spring annual sea ice at Terra Nova Bay (Ross Sea,Antarctica)

The aim of this study was to investigate patterns of abundance, distribution, temporal changes and species composition of the dominant ice-associated copepods in the spring annual pack ice, platelet ice and water column at Terra Nova Bay, Ross Sea, during late spring 1997. Ice cores were drilled for temporal and spatial scales. Stephos longipes and Harpacticus furcifer dominated the sea ice meiofauna in terms of numbers in the lower few centimeters of the bottom ice associated with high chlorophyll a and phaeopigment levels. Nauplii dominated the S. longipes population (91.6%) and occurred in extremely high concentrations. In contrast, copepodids were the dominant stages in H. furcifer. How H. furcifer carries out its entire life cycle and how it differs from ecologically similar species such as Drescheriella glacialis should be examined in more detail.     

Chemical recognition by hermit crabs of their symbiotic sea anemones and a predatory octopus

The ability of the hermit crabs Dardanus venosus and Pagurus pollicaris to recognize chemically their symbiotic sea anemone Calliactis tricolor and a common octopus predator, Octopus joubini, were studied. The crabs were tested for chemoreceptive responses using a Y-trough olfactometer, which prevented visual cues from being used. Choice tests showed that D. venosus could chemically detect Calliactis. If, however, D. venosus had a Calliactis on its shell at the time of the trial, it could not detect the test anemone. P. pollicaris (without a symbiotic anemone) did not locate the test anemone. Both species of crab avoided a water current carrying octopus chemical cues. Chemoreception may play an important role in the interaction of a hermit crab with its symbiotic anemone and an octopus predator.     

A study of the spirocytes from the Ceriantharia and Actiniaria (Cnidaria: Anthozoa)

Summary The structure and ultrastructure of ceriantharian and actiniarian spirocysts were compared. In the ceriantharian spirocyst, the apical cap consisted of two layers and the wall consisted of three, whereas in the actiniarian spirocyst, the number of layers was reversed. The inner wall of the ceriantharian spirocyst was smooth in longitudinal section whilst that of the actiniarian was serrated. The apical ends of ceriantharian spirocytes posessed either a set of microvilli or an arrangement that included both microvilli and a flagellum. The actiniarian spirocyte possessed only microvilli. Fine tubules occupying the undischarged tube of the ceriantharian spirocysts were of both moderate and strong electron densities, whilst those of the actiniarian were consistently electrondense. Undischarged ceriantharian spirocytes possessed tubules situated in the pleats and in the centre of the tube, whilst the tubes of undischarged actiniarian spirocytes possessed only centrally placed tubules. Fine electron-dense filaments linking the cell membrane to the spirocyst were present at the apical ends of actiniarian spirocytes. A different electron-dense network of filaments was present in the apical end of ceriantharian spirocytes. All cnidae of ceriantharians lacked tripartite opercula whilst the nematocysts of actiniarians possessed them. Primitive features of ceriantharian cnidae are discussed.     

High abundance of Myriochele fragilis Nilsen & Holthe, 1985 (Polychaeta: Oweniidae) in the deep sea of the Eastern Mediterranean

An exceptionally high abundance of Myriochele fragilis Nilsen & Holthe, 1985 (Polychaeta: Oweniidae) is reported for the Ierapetra Basin in the Eastern Mediterranean Sea from depths of 4159 and 4260 m, representing the first record outside the Norwegian and Arctic Sea and extending the depth range by more than 1600 m. Specimens are described and compared to closely related species.