Question

The name of phylum is derived from certain features of animals. Select how many of these are correct.
a. Cnidaria- Cnidoblasts / cnidocytes
b. Flatworms- Dorsoventrally flattened body
c. Platyhelminthes- Circular cross section
d. Aschelminthes-Body surface is indistinctly marked out into segments or metameres
e. Echinodermata - Exoskeleton of calcareous ossicles

Answer 1

Correct statements
Statement a: Cnidaria- Cnidoblasts / cnidocytes
Cnidoblasts, also known as cnidocytes, are ‘stinging cells’ present on the tentacles and the body of the members of the phylum Cnidaria (earlier known as Coelenterata). They contain an organelle called nematocysts that serve as an organ of prey capture, defence and for locomotion. Hence statement ‘a’ is correct.

Statement b: Flatworms- Dorsoventrally flattened body
Members of the phylum Platyhelminthes are called flatworms as their bodies are dorso-ventrally flattened from head to tail, soft and they appear ribbon-like. Hence statement ‘b’ is correct.

Statement d: Aschelminthes- Body surface is indistinctly marked out into segments or metameres.
Members of the phylum Aschelminthes are roundworms like Ascaris, that appear circular in cross section and do not have distinctly marked out body surface into segments or metameres. Hence, statement ‘d’ is correct.