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. A veliger is found strictly in terrestrial molluscs
b. The trochophore is considered ancestral and the veliger is a derived larval stage
c. The two larval forms represent two early and distinct branches of molluscs
d. The veliger is ancestral and the trochophore is a derived larval stage
e. Only the cephalopods have the veliger stage; all other molluscs have a trochophore stage


Answer: b. The trochophore is considered ancestral and the veliger is a derived larval stage

Biology & Microbiology

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