Question

LE
5. Give reasons for the following:
(a) from Phylum Platyhelminthes onwards animals are categorised as triploblastic
of the presence of coelom in an animal's body is considered as advantageous​

Answer 1

The presence of three germ layers gives rise to new organs and their development (in the other phylla), which enhance the organism's bodily functions as well as develop new bodily funcions.

Answer 2

Explanation:

Animal are classified on the basis of symmetry of body plan and germ layers if the body plan is made up of three germ layers called as triploblastic and if it made up of two germ layers called as diploblastic. Ctenophores are biradially symmetrical and diploblastic, whereas some species are triploblastic.

Sponges are asymmetrical and and diploblastic.

Coelenterates are radially symmetrical and diploblastic.

Aschelminthes are bilaterally symmetrical and triploblastic.