Question

Annelida and mollusca resemble in many embryonic features because both have

• A. Spiral cleavage and mesoderm formation
• B. Identical conspicuous segmentation in body, muscles and nervous system
• C. Meroblastic cleavage and ectoderm formation
• D. Special types of mouth parts

Answer 1

The correct option is A Spiral cleavage and mesoderm formation

Mollusca and Annelida probably have evolved from free-living flatworms. They both show resemble many embryonic features. Molluscs are protostomes. They are developed by spiral cleavage. Their embryonic cells are determinate. They show mesoderm formation. The coelom is developed from a split within the mesoderm tissue. Hence, they are also called as schizocoelous.

Thus, the correct answer is option A.