Question

Trochophore larva is found in
A. Annelida
B. Mollusca
C. Coelenterata
D. Both A and B

Answer 1

Hint: Trochophore larva is a small, ciliated, unsegmented and pear-shaped creature. They are planktotrophic animals. They are found in marine environments. They move in a wheel like movement with the help of cilia. This larva is a characteristic of many protostomes groups of animals and exists as a larval form within the trochozoa clade.

Complete answer:
Option A Annelida: Phylum annelida is a very broad phylum in the animal kingdom. They are triploblastic, bilaterally symmetrical and segmented Metazoa. Some of the annelids belong to the Lophotrochozoa lineage. Trochophore larva occurs in phylum annelida. This option is correct but there are more than one answer in the given options.
Option A is incorrect.
Option B Mollusca: Mollusca is one of the largest marine phylums. They also live in freshwater and terrestrial habitats. They are bilaterally symmetrical and stratified. Trochophore also occurs in molluscs. This option is also correct but we also have annelida.
Option B is incorrect.
Option C Coelenterata: Phylum Coelenterata is a group of aquatic or marine organisms. They are normally found attached to the rocks at the bottom of the sea. They are multicellular and invertebrate animals. They also exhibit a tissue-level organization. Trochophores do not occur in coelenterata.
Option C is incorrect.
Option D Both A and B: Since both the Phylum Annelida and Mollusca have trochophore larvae in them, this option is correct.
Option D is correct.

Hence, Option D) Both A and B are correct answers.

Note:
The Trochophore larvae is of great phylogenetic significance. Many animals such as polychaetes, sipunculans, bryozoans develop a trochophore larva with certain modifications. The trochophore larva grows and develops by proliferation of tissue in the growth zone. During metamorphosis the planktonic life of the trochophores ends and loss of various larval structures occur.