Question

All non-chordates are schizocoelomates and chordates are enterocoelomates. Do you agree with the above statement? Give reasons for your positive or negative answer

Answer 1

Schizocoelomates and enterocoely are categorized based on the body cavity (coelom). Coelom of schizocoelomates arises from a layer of mesoderm. Coelom of enterocoelomate arises from out pocketing of the embryonic gut. Not all the non-chordates are schizocoelomates and not all the chordates are enterocoelomates. Some of the exceptions are there in the groups.

Complete step by step answer:
Coelom is the body cavity present in most of the animals. It surrounds the body and contains the digestive tract and other organs. In some of the animals such as Schizocoelomates coelom develops as a split in the mesoderm. One part of the cavity attaches to the ectoderm while other surrounds the endoderm. The space in between is called a coelom. These animals have true coelom as it is lined by the mesoderm. The internal organs are held in place by mesenteries. It includes phylum Annelida and
Arthropoda.
The coelom in Enterocoelomates is formed from the poches of archenteron or primitive gut. Phylum Chordata and phylum Echinodermata are examples of enterocoelomates. Presence or absence of a notochord helps to differentiate between chordates and non-chordates. Enterocoelom is present in the deuterostomes. The fusion of internal outgrowths of the archenteron contributes in the formation coelom. We do not agree with the statement given in the question. All non-chordates are not schizocoelomates. Phylum porifera are known as acoelomate while phylum Aschelminthes and Nematoda are pseudocoelomates.

Note: In chordates notochord is present at one stage of their life cycle. Notochord is absent in non-chordates. Chordates are cold-blooded or warm-blooded while all the chordates are cold blooded. Chordates are triploblastic. Non-chordates can be either triploblastic, diploblastic or neither. Non-chordates can be coelomates, acoelomates or pseudocoelomates.