Question

In echinoderms, ossicles are

• A. Exoskeletal plates
• B. Endoskeletal plates
• C. Regions of ambulacral grooves
• D. Regions from where oral tentacles develop

Answer 1

The correct option is B Endoskeletal plates

A) They do not have exoskeletal plates, but they have endoskeletal plates called ossicles.

B) Echinoderms have mesodermal endoskeletal plates which are calcareous and are called ossicles.

C) Echinoderms have ambulacral parts like ossicles, plates, spines, and suckers in the ambulacral groove.

D) Oral tentacles are present around the mouth while ossicles are present uniformly over the surface of the echinoderm.

So the correct answer is 'Endoskeletal plates'.