The color of blood is related to the compounds that transport oxygen. For example, hemoglobin containing iron is red and is found in all vertebrates and a few invertebrates. Annelids (segmented worms) have either a green pigment, chlorocruorin, or a red pigment, hemerythrin. Some crustaceans (arthropods having divided bodies and generally having gills) have a blue pigment, hemocyanin, in their blood.