For many years our laboratory has investigate the jelly coat that surrounds the eggs from sea urchins. This egg jelly is mostly composed of a sialoglycoprotein and a sulfated polysaccharide, mainly a fucose polymer. We have already studied the egg jellie's composition from seven species and in all of them we have found a sialoglycoprotein and sulfated fucans with regular and repetitive units. Until now, only E. lucunter, a species found in the south Atlantic ocean, exhibits a sulfated galactan composed of 3-alfa-L-Galp2(OSO₃)-. But in G. crenularis, a sea urchin from deep sea, collected in Japan, we found a totally distinct egg jelly composition. First, this species does not contain sialoglycoprotein. Second, the sulfated polysaccharide is a galactan, instead of a fucan, composed of disaccharides units, within the following structure: 3-alfa-L-Galp2(OSO₃)-1-2-beta-L-Galp, as revealed by NMR spectra. This is the first report of a sea urchin that does not present the sialoglycoprotein, an important component for the acrosome reaction, which is an obligatory event for the success of fertilization. We already tested the sulfated galactan of G.crenularis as an inducer of the acrosome reaction in the heterologous sperm of E. lucunter, and observed that this polysaccharide was less potent than the homologous sulfated galactan (approximately 50% of activity compared with the homologous polysaccharide). We are now performing experiments in the opposite way that is, using sperm of G. crenularis to study fertilization with the two sulfated galactans. We hope these studies will help us to obtain an overview of the sea urchin evolution and species diversity due to a carbohydrate-based mechanism of species recognition. Financial Support: CNPq, IFS and FAPERJ.