Question

Which of the following phylum do not posses true coelom.Why?
(a) Aschelminthes (b) Annelida (c) Ctenophora (d) Platyhelminthes

Answer 1

Dear student,
(a) Aschelminthes (c) Ctenophora & (d) Platyhelminthes
Coelom: Presence or absence of a cavity between the body wall and the gut wall. The body cavity, which is lined by mesoderm is called coelom.
Coelomates: Animals possessing coelom are called coelomates e.g., annelids, molluscs, arthropods, echinoderms, hemichordates and chordates.
Pseudocoelomates: Body cavity is not lined by mesoderm, instead, the mesoderm is present as scattered pouches in between the ectoderm and endoderm. Such a body cavity is called pseudocoelom and the animals possessing them are called pseudocoelomates, e.g., aschelminthes.
Acoelomates: The animals in which the body cavity is absent are called acoelomates, e.g., Platyhelminthes, Ctenophora
Regards