Phyla Echinodermata

Phylum Echinodermata Sea lilies, seastars, sea urchins, sand dollars, sea cucumbers... 

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. 

More than 460 compounds are included. It is worth noting that while sulfated marine metabolites are mostly found in the phylum Echinodermata (350 out of 500), the non-sulfated systems are more widely distributed among all the phyla. 

In the sixties, however, sialoglycolipids were found in the tissues of some invertebrates, the sea urchins Arbacia punctuata,64 Pseudocentrotus depressus,6S and Strongylocentrotus intermedius.66 These compounds were soon found in other species belonging to the phylum Echinodermata, and their systematic study began. 

Further work in the phylum Echinodermata shows a variable ability to biosynthesize steroids. In the class Holothuroidea and Echinoidea, the representatives examined could synthesize squalene but not triterpenoids or sterols from acetate. However, several examples from the class Asteroidea were able to synthesize squalene, lanosterol, and other steroids. In the later stages of steroid metabolism it was shown that cholesterol was converted into cholest-7-enol via cholestanol. 

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 Asteroidea and Holothuroidea, the phylum Echinodermata (Greek echinos, spiny derma, skin) comprises the classes Ophiuroidea (brittle stars), Crinoidea (sea lilies and feather stars) and Echinoidea (sea urchins). There is no report of occurrence of steroid or triterpenoid glycosides in sea lilies, feather stars or sea urchins. Brittle stars contain sulfated polyhydroxylated steroids [10-12] and only two sulfated steroidal monoglycosides have been isolated from the brittle star Ophioderma longicaudum [13]. 

SALMFamide peptides, a family of neuropeptides isolated from species belonging to the phylum Echinodermata. SALMFamide-1 (SI) H-Gly-Phe-Asn-Ser-Ala-Leu-Met-Phe-NHz and SALMFamide-2 (S2)SGPYSFNSGL TFaarethefirstmem-bers of this family found in the radial nerve cords of the starfish (class Aster-oidea). SI and S2 are present in the in-... 

Sea cucumbers belong to the phylum Echinodermata, class Holothuroidea, and are thus also called holothuroids. Of the approximately 1400 species that have been described so far, some 77 are harvested commercially at various scales around the world (Purcell et al, in press). While the footballshaped shmy creatures are not necessarily attractive at first glance, they are nonetheless a prized commodity. 

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). 

As mentioned in Figure 26.1, ophiuroids may be considered chemically marginal in the phylum Echinodermata because they have the characteristics of crinoids and... 

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