Sulfated glycosaminoglycans were isolated from 23 species of 13 phyla of invertebrates and characterized by their electrophoretic migration in three different buffer systems coupled with enzymatic degradation using bacterial heparinase, heparitinases and chondroitinase AC. Heparan sulfate is a ubiquitous compound present in all species analyzed whereas chondroitin sulfate was present in 20 species and heparin-like compounds in 12 species of the invertebrates. The heparin-like compounds were purified from the echinoderm Mellita quinquisperforata (sand dollar) and the crustacean Ucides cordatus (crab) with anticoagulant activities of 60 and 52 IU/mg, respectively. Degradation of these heparins with heparinase produced significant amounts of the trisulfated disaccharide typical of mammalian heparins. This was confirmed by 13C-NMR spectroscopy of the crab heparin. An updated phylogenetic tree of the distribution of sulfated glycosaminoglycans in the animal kingdom is also presented.