Echinodermata, echinoderms

Kalinin. V.I., Anisimov, N.N., Prokofeva, N.G., Avilov, S.A., Afiyatulov, S.S., and Stonik, V.A. (1996a) Biological activities and biological role of triterpene glycosides from holothuroids (Echinodermata). Echinoderm. Stud., 5,139-181. 

Echinodermata (Echinoderms) 7000 Marine benthic free-living invertebrates, calcium carbonate... 

Coelenterates and Echinoderms. In the phylla Coelenterata and Echinodermata approximately 90 species have been investigated for toxicity (see Tables II and IH). Only 20 or so have been extensively studied (e.g., sea anemones, sea cucumber, and jellyfish). Even so, while relatively complete studies have been made on isolation, characterization, and elucidation of mechanisms of action, in no one species have all of the toxins present been identified. Thousands of species have not been subjected to even the most cursory examination. 

The phylum Echinodermata comprises about 7000 living species [177]. Echinoderm means spiny-skinned and these organisms are characterised by the tube feet, which they use to move about. These have suction discs on the ends, which operate by an internal bulb pumping water in and out of the foot, causing expansion and contraction. The phylum is sub-divided into five classes the asteroids (sea stars), the holothurians (sea cucumbers), the crinoids (sea lilies), the echinoids (sea urchins) and the ophiuroids (brittle stars) [178]. As stated in the introduction to this review, sulfated sterols and saponins, which comprise the majority of echinoderm metabolites containing sulfur, are not included here. 

The echinoderms (phylum Echinodermata) include starfish, sea-urchins, sea cucumbers, and crinoids. A great many of these organisms were fossilized because they have skeletons made of calcite plates. The greatest number of different genera of echinoderms lived during the Carboniferous (360-286 million years ago). The embryology of modern echinoderms suggests that they are... 

In addition to cholesterol and 5a-cholest-7-en-3y8-ol, many C2g and C29 conventional sterols are present in Echinodermata. These sterols are probably derived from the diet. However, echinoderms are able to synthesize sterols. Thus, [ C]mevalonic acid was incorporated into squalene, lanosterol and desmosterol by the sea urchin. Echinus esculentus [87]. The ability of ophiurpids to synthesize sterol from [ C]acetate has also been demonstrated [88]. Sterol biosynthesis by a holothuroid was first investigated by Numura [89], and sterol biosynthesis from [ C]acetate in sea cucumbers has also been reported [90]. 

I toxins. Among the echinodermata, the stalked grasping organ (pedicellaria) of isolated species of sea urchins and st sh may also serve as a poison weapon. The sea urchin Toxopneustes pileolus is much feared in East Asian waters. Other species of sea urchins also possess poisonous spines (e.g., Diadema setosum). The chemical composition of the venoms is mostly unknown. The cuvierian organs extruded from the cloaca of sea cucumbers when disturbed from sticky fibers in water may also secrete a venom, e.g., the holothurins see also echinoderm saponins. 

Jefferies, R.P.S. (1988) How to characterize the Echinodermata—some implications of the sister-group relationship between echinoderms and chordates , in Paul, C.R.C. and Smith, A.B. (eds) Echinoderm phylogeny and evolutionary biology, Liverpool Geological Society and Oxford Clarendon Press, pp. 3-12. 

Investigation of protostomates, believed to be older than the echinoderms, e.g. Brachiopoda and Bryozoa also gave negative results for sialic acid. In order to confirm the Echinodermata as the initial sialic acid-containing phylum, further comparative studies of phyla believed to have developed at this stage in evolution must be carried out. 

The chemotaxonomic relations observed in the phylum Echinodermata are particularly clear each class is characterized by a particular set of secondary metabolites that is probably specific to the class. For the class Crinoidea, these are anthraquinonic pigments, often sulfated, which have been found in all species studied. The other four classes of echinoderms also contain quinonic pigments but these are naphthoquinones, which are widespread among Echinoidea (spinochromes), rare in Asteroidea and Ophiuroidea, and exceptional among Holothuroidea (Scheuer, 1973). 

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