Question

In some molluscs, the free-swimming larva is a trochophore, while in others, it is a veliger with the beginnings of a foot, shell, and mantle. What is the relationship of these molluscan juvenile stages?

a. Trochophore is an earlier stage than veliger.
b. Veliger is an earlier stage than trochophore.
c. Trochophore and veliger are different developmental paths.
d. Trochophore and veliger are synonymous terms.

Answer 1

The molluscan juvenile stages are sequentially related, with the trochophore as an earlier larval form followed by the more developed veliger stage.

Step-by-step explanation:

The relationship of the molluscan juvenile stages trochophore and veliger can be understood through their developmental sequence. The trochophore is an earlier larval stage found in the life cycle of many mollusks, characterized by bands of cilia for movement and an apical tuft of cilia.

This stage is followed by the veliger stage in some species, which represents a more developed larval form with beginnings of a foot, shell, and mantle, indicating that it is a later stage in development. Thus, the correct relationship is that trochophore is an earlier stage than veliger.