Question

Which of the following organisms would you expect to have the largest surface-area-to-volume ratio? Assume that all of the following are the same total length.

A) a mollusk
B) an annelid
C) an arthropod
D) a platyhelminth

Answer 1

The correct answer is: D) a platyhelminth

A platyhelminth is a simple unsegmented soft-bodied flat worm with bilateral symmetry.

Since they don’t have any respiratory and circulatory organs, respiration occurs through the whole surface of the body. So, this type of worm has a great surface area in order to absorb more oxygen.