Question

Identify a deuterostome.
A. Leucosolenia
B. Dentalium
C. Dugesia
D. Ophiothrix

Answer 1

All the echinoderms and chordates are deuterostomes and in deuterostomes, the blastopore is developed into an anal opening. The blastopore in deuterostome is developed into an anal opening.

Complete answer:
Deuterostomes constitute a super phylum of animals. Most of the deuterostomes belong to two groups and the majority of members are the echinoderms which include skinned starfish, sea urchins and their relatives and the chordates which include fish and other vertebrates. All the echinoderms and chordates are the deuterostomes. In deuterostomes, the blastopore is developed into an anal opening.
Protostomes are the primary invertebrates, the blastopore is developed into a mouth. These include the animals which undergo protostome during the embryonic development. It includes a group of animals which are arthropods, molluscs, annelid worms.

Option A is Leucosolenia. It belongs to porifera so it is a poriferan which is a protostome not deuterostomes. Therefore, this option is not the correct one.
Option B is Dentalium. It is a mollusc and molluscs are protostome. Therefore this option is also not the correct one.
Option C is Dugesia and it is flatworm which belongs to platyhelminthes and these are protostome therefore it is not the correct option as deuterostome is asked.
Option D is Ophiothrix. It is an echinoderm and all the echinoderms are deuterostomes. Therefore, this option is the correct one.

Hence, the correct answer is option (D).

Note: Echinoderms are considered as deuterostomes because they have unique feature which is water vascular system and the echinoderms are bilaterally symmetrical as larvae and therefore they meet deuterostome criteria even though they change shape as they become mature.