Question

Triaxon spicules occur in

• A. Hexactinellida
• B. Calcarea
• C. Demospongiae
• D. All the above

Answer 1

The correct option is A Hexactinellida

A. Sponges of class Hexactinellida are also called glass rope sponges. Spicules are siliceous and six-rayed or triaxon.

B. Sponges of class Calcarea are small sized calcareous sponges with solitary and colonial habitat. Spicules are calcareous and monoaxon.

C. Sponges of class Demospongiae have skeleton of siliceous spicules or spongin or both. Spicules are mostly monoaxon or tetraxon, but never triaxon.

Hence, triaxon spicules occur in hexactinellida.

So, the correct answer is 'Hexactinellida'.