GENERAL HISTOLOGY

Detailed explanation-1: -Aside from the water vascular system, echinoderms have a haemal coelom, a perivisceral coelom, a gonadal coelom and often also a perihaemal coelom.

Detailed explanation-2: -The echinoderm coelom is well-developed, and it forms two major cavities during development. One cavity becomes the actual coelom that houses internal organs, while the other develops into the water vascular system.

Detailed explanation-3: -Echinoderms also have a spacious coelom (an open, fluid-filled body cavity lined with tissue), large gonads, and (usually) a complete gut.

Detailed explanation-4: -The only phylum of animals to possess a false coelom or a pseudocoelom is the Aschelminthes or the roundworms which include organisms such as Ascaris. In these protostomes, the embryonic blastocoel persists as a body cavity.

Detailed explanation-5: -Some animals possess a “false” coelom called a pseudocoelom. These animals are known as pseudocoelomates. A pseudocoelom is a body cavity that lies between mesodermal and endodermal tissue and is, therefore, not completely surrounded by mesodermal tissue.