Question

Phylum Annelida resembles Mollusca in embryonic features as both have

• A. Spiral cleavage and mesoderm formation
• B. Meroblastic cleavage and ectoderm formation
• C. Special types mouth parts
• D. Trochophore larva in their life cycle

Answer 1

The correct option is D Trochophore larva in their life cycle

Phylum Annelida and phylum Mollusca both are invertebrates. In both the phylum, reproduction is by asexual and sexual means depending on the species. In Annelida, external fertilisation takes place in dioecious organism whereas internal fertilisation takes place in a monoecious organism. In Mollusca, fertilisation may be internal or external. In external fertilisation, they swim to the surface and release their gametes into the water, where fertilisation takes place. In both the phylum, the fertilised eggs develop into larvae before getting transformed to adults. There may be one or more larval stages. Each one is different from the adult stage. They have a unique larval form called a trochophore. Trochophore is a tiny larval organism with bands of cilia for swimming.

Thus, the correct answer is option D.