Echinoderms classes

The increased occurrence of the bioluminescence in ophiuroids suggests that luminescence is more widespread than initially thought, raising questions about the functional importance of luminescence in this echinoderms class. 

Janies, D. (2001) Phylogenetic relationships of extant echinoderm classes. Can. J. Zool., 79,1232-1250. 

Goad (40) and others have extensively reviewed coelenterate and echinoderm sterols including the saponins found in starfish and sea cucumbers. Cholesterol is a common sterol in most families, except for gorgonians and zoanthids some soft corals contain polyhydroxylated sterols. The amount of variation associated with phylogeny is illustrate in the echinoderms by the fact that crinoids, ophuiroids, and echinoids contain A 5 sterols while holothuriodeans and asteroids contain A 7 sterols. Some classes contain uniquely structured sterols. 

The aquatic species chosen was Strongylocentrotus purpuratus, the purple sea urchin. This animal is a common resident of the California coast, a frequent pest in commercial kelp culture, and a specialty food item of growing interest. Phylogenetically, these echinoderms are considered to be in the invertebrate class most directly linked to the vertebrates. 

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 compounds most characteristic of the phylum are the saponins, glycosolated sterols, most of which are sulfated. The suite of secondary metabolites produced by the classes Asteroidea, Ophiuroidea, and Holothuroidea are dominated by these sterols. It is believed that echinoderms do not generally undertake de novo synthesis of these sterols, but create them by modifying precursors obtained through feeding.90... 

In the marine life, 700 genera representing 13 phyla contain luminous specimens, Echinoderms represent a major phylum of benthic organisms and although their ability to produce light has been reported for decades, little is known about bioluminescence in this phylum. In echinoderms, four of the five classes contains luminous representatives (Fig. lA), a total number of 91 luminous species are now reported. ... 

B) Relative abundance of species within four classes of echinoderms known to contain luminous representatives. 

Despite the reasonable number of luminous species, a. literature survey of the last thirty years provided us with limited information about echinoderm luminescence. Inspection of luminous echinoderms listing reveals that within the echinoderm phylum bioluminescence is not uniformly distributed in each classes with 38 and 30 species, ophiuroids and holothurians represent 78 % of the echinoderm luminous species while asteroids and crinoids correspond respectively to 23 and 3% of the phenomenon. The total absence of luminescent species in echinoids remains unsolved (Fig. IB). It must be pointed out that when available, echinoderm luminescence studies have been mostly carry out on the ophiuroids largely because some species are easily observable in situ, collected and kept in captivity allowing experimental works. 

Another class of compound that can be difficult to purify is the saponins found in Echinoderms. Almost all echinoderms examined to date contain either polyhydroxylated sterols or terpene glycosides, many of which contain sulfate ester functionality. The purification of compounds (Schemes 6-9) (40) from the starfish Nardoa tuberculata exemplifies the procedure most often used to purify these metabolites (Fig. 2). 

Barrande, J. (1887) Systems silurien du centre de la Boheme. Vol. VII. Classe des echinodermes, ordre des cystidees, Prague Barrande. 

Ubaghs, G. (1961) Un echinoderme nouveau de la classe des carpoides dans I ordovicien inferieur de departement de I Herault (France) , Comptes rendus des Seances de la Societe Biologique, 253, 2565-7. 

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