Some animals have no gills when young but then develop gills that grow larger as the animal grows larger. What is the reason for this increase in gill size?
A) Relative to their surface area, the young have more body volume in which they can store oxygen for long periods of time.
B) The young of these animals are much more active than the adult, which leads to a higher BMR basal metabolic rate) and, therefore, a higher need for oxygen.
C) The young have a higher basal metabolic rate.
D) Relative to their volume, the young have more surface area across which they can transport all the oxygen they need.

Question

Quizplus · Accepted Answer

Young animals have a smaller body volume but a larger surface area, which means they need more oxygen per unit of body volume than adults. As a result, they need a larger surface area for gas exchange, and their gills grow larger to fulfill this need.

Some Animals Have No Gills When Young but Then Develop