Starfish may be described in terms of their symmetry, germ cell layers, coelom, circulatory system, reproduction, feeding, excretion, and nervous system. Echinodermatas have a five-rayed symmetry where they are presents as radial or bilateral. As for layers, they have over two layers including several organs and tissues. In terms of body cavity, they are coeloms. They do no have gills, instead they have an open circulatory system. For reproduction, it is usually through gonochoristic sexual reproduction. They feed through a mouth that is located in the center of their backs and is broken done inside. Echinodermatas do not have excretory organs; however, they have a circum-oesophageal ring as their nervous system. Below are image examples of the living classes of Crinoidea, Ophiocistioidea, Astroidea, Echiinoidea, and Holothuoidea.
Crinoidea
Sources: http://www.earthlife.net/inverts/echinodermata.html
google images
No comments:
Post a Comment