In echinoderms

In echinoderms, zinc concentrations are usually higher in detrital feeders than in carnivores, higher in surface feeders than in sediment feeders, and higher in specimens collected inshore than those collected offshore in deeper waters (Eisler 1980). Sea cucumbers, Stichopus tremulus, accumulate radiozinc-65 from seawater by a factor of 1400 however, radiozinc accumulation data should be viewed with caution because addition of stable zinc can reduce zinc-65 accumulations in echinoderm viscera up to tenfold (Eisler 1981). Zinc inhibits the formation of the fertilization membrane in sea urchin eggs, possibly by interfering with cortical granule-derived proteases and proteins (Nakamura et al. 1989). 

However, the presence of specific glycolipids, the sialoglycolipids, seems to be directly associated with the evolutionary position of the animal. Sialoglycolipids, found in all vertebrates, have also been found in echinoderms, which, together with vertebrates and the other chordates,... 

Heatfield, B.M., 1970. Calcification in echinoderms effects of temperature and Diamox on incorporation of calcium-45 in vitro by regenerating spines of Strongylocentrotus purpuratus. Biol. Bull., 139 151—163. 

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. ... 

Figure 1. (A) Total number of species and known luminous species in echinoderms ...

Mallefet, J. Physiology of bioluminescence in echinoderms. In Candia Carnevali, MD, Bonasoro F. eds. Echinoderm Research 1998. Rotterdam Balkema 1999 93-102. 

The adult pentaradial symmetry shown by sea urchin seems to contradict the general head-associated Otx expression rule. It is generally held that the radial symmetry in echinoderms is a shared derived character (synapomorphy) because of their embryonic and larval bilateral symmetry (Lowe and Wray, 1997). Thus the highly divergent and non-head specific Otx expression in sea urchin can be justified as a consequence of the highly modified body plan of this phylum. 

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). 

With the exception of two sea urchin samples collected from Puerto Rico, most chromium residues reported in echinoderms have been less than l.Omg/kg DW. The elevated levels of 24.0 and 43.0mg/kg FW of whole organism in Puerto Rican sea urchins are exceptions, which were not reflected in sea cucumber muscle from the same vicinity, and thus should be viewed with caution. Echinoderms from the United Kingdom and environments were comparatively low in chromium concentrations were less than 0.46 mg Cr/kg DW whole organism. Embryos of a sea urchin (Anthocidaris sp.) developed normally in solutions containing 3.2. 2 mg Cr/L, but failed to develop at 8.4-10.0 mg Cr/L. Larvae of another species of sea urchin (Hemicentrotus sp.) were more sensitive, showing abnormal development or dying within 24 h at concenttations of < 1.0 mg Cr/L. Hexavalent chromium at 6.0 mg/L was associated with abnormal development in embryos of Anthocidaris crassispina. 

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