Question

Identify me.
I Am diploblastic and acoelomates. Which phylum do I belong to?

Answer 1

Hint: Diploblastic organisms are the ones which consist of two germ layers namely ectoderm and endoderm whereas triploblastic organisms consist of three germ layers called ectoderm, mesoderm and endoderm. Based on the presence or absence of coelom, these are divided into coelomates, pseudocoelomates and acoelomates.

Complete answer:
Coelom is nothing but the body cavity that is formed during embryonic development that is present in between the alimentary canal and the body wall. In acoelomates, the body cavity is absent and is completely occupied by mesoderm. Examples include Porifera, Cnidaria. In pseudocoelomates, only the partial body cavity is lined with mesoderm hence it is said to be false coelom Ex: roundworms. In coelomates, the mesoderm is present towards the body wall and also the gut and hence are called true coelomates or acoelomates. Ex: annelida, arthropoda etc. As the terms diploblastic and triploblastic have been discussed, let us see the examples of it. The diploblastic animals include Cnidaria which is acoelomate and Ctenophora which is pseudocoelomate whereas triploblastic animals include arthropods, molluscs etc. By the above explanation, the phylum that includes diploblastic and acoelomate organisms is Cnidaria.

Hence, the correct answer is Cnidaria.

Note:
The diploblastic animals do not have a true body cavity as they lack mesoderm which is found in coelomates. Hence, all the triploblasts are coelomates. The other distinguishing feature between them is that diploblastic animals have radial symmetry whereas triploblastic animals have bilateral symmetry. In diploblasts instead of mesoderm, mesoglea is present.