A carbohydrate-based mechanism of species recognition in sea urchin fertilization. P.A.S. Mourão. Braz J Med Biol Res 2007; 40: 5-17.   

Figure 2. Structures of sulfated polysaccharides from marine invertebrates. The figure shows 9 fully characterized structures of sulfated polysaccharides from the egg jelly of sea urchins and the tunic of ascidians. The specific pattern of sulfation and the position of the glycosidic linkage vary among sulfated fucans from different species. The structures of some a-L-galactans are also included in the figure. L-galactose and L-fucose are closely related sugars, differing only by the CH2OH and CH3 radicals at position 5, respectively. In fact, a common designation for L-fucose is 6-deoxy-L-galactose.