Question

Define the terms and give one example of each
(1) Bilateral symmetry
(2) Coelom
(3) Triploblastic

Answer 1

Answer:

(1) The animals with Bilateral symmetry are put in group bilateria. The body can be divided into two identical right and left halves in only one plane. e.g., Annelids, arthropods, etc.

(2) Coelom is the body cavity present between the body wall and the gut wall. Presence or absence of Coelom is very important basis of classification.

(a) Acoelomate- Coelom is absent. e.g., poriferous, coelentrates and flatworms.

(b) Pseudocoelomate- The body cavity isn't lined by mesoderm instead it is present as scattered pouches in betweene mesoderm and endoderm. e.g., round worms.

(c) Eucoelomate- Present of true Coelom. True Coelom is of two types

• Schizocoelom- Develops by splitting up of mesoderm.
• Enterocoelom- The mesoderm arises from wall of embryonic gut.

(3) Germ layers give rise to all the tissues/organs of the fully formes individuals. On the basis of number of germ layers animals can be

(a) Diploblastic- The body cells are arranged in two layers on outer ectoderm and on inner endoderm, e.g., coelentrates.

(b) Triploblastic- Body wall of animals is made up of three germ layers i.e., ectoderm, mesoderm, and endoderm e.g., platyhelminthes to chordates.