Question

Write short notes on:
(a) Coelom (b) Metamerism (c) Notochord

Answer 1

(a) Coelom: The body cavity, which is lined by mesoderm (on both sides) is called coelom. Animals possessing coelom are called coelomates. Coelom is a cavity between alimentary canal and body wall enclosed by mesoderm on both sides. E.g. Annelids, Arthropods, Molluscs, Echinoderms, Hemichordates, and Chordates.

(b) Metamerism: In some animals, the body is externally and internally divided into segments. For example, in the earthworm, the body shows this pattern called metameric segmentation and the phenomenon is known as metamerism or true segmentation. Metamerism is found in 3 animal phylum - Annelida, Arthropoda, and Chordata.

(c) The notochord is a mesodermally derived rod-like-structure formed on the

dorsal side during embryonic development in some animals and it is the part of the skeletal system. Nerve cord is the part of the nervous system.