What are Echinoderms?
Echinoderms are a very old phylum of marine animals whose name means “spiny skin” in Greek. This name is a misnomer, however, because not all echinoderms have spines. Their more fitting universal trait is common ancestry, including a unique water-based vascular system, and frequent five-fold symmetry. Though they do not always display five-fold symmetry (sea cucumbers are echinoderms, and they have bilateral symmetry), echinoderms are known for often playing games with the typical bilateral symmetry trend, as in sea urchins (radial symmetry), and the numerous starfish and sand dollars (five-fold symmetry). Echinoderms are one of several phyla that is exclusively marine. The first known echinoderm is thought to be Arkarua, an ancient disc-like fossil about 1 cm in diameter with a five-fold pattern of dents that leads scientists to classify it as a likely echinoderm. This fossil dates to the Late Ediacaran, about 550 million years ago. Other than that, the first certain echinoderms appea
Echinoderm: the name means spiny skin but we aren’t talking about porcupines, unless we rename sea urchins the porcupines of the sea. Sea urchins are the spiniest members of the marine phylum Echinodermata. Other echinoderms are starfish, brittle stars, the lesser known crinoids, and the sea cucumbers, the least spiny of the lot. They are a strange lot, with no eyes or brains, radially symmetrical, with rows of tube feet around a central mouth from which the stomach sometimes protrudes, and yet they are distant relatives of the chordates, our own phylum.
Page Description: In this science printable about invertebrates, students will evaluate true/false statements about echinoderms and use reference materials to identify drawings of a sea cucumber, a starfish, a sand dollar, and a sea urchin. Grade Levels: 6 – 12 The full page is available ONLY to subscribers. Sign up today for a free 7-day trial to get access to this page and all of the 20,000 items on TeacherVision.
