Animals that swim expend less energy to move than do animals that walk or fly because
A)water provides less resistance than air.
B)gravity has more impact on aquatic animals than it does on terrestrial animals.
C)aquatic animals do not have to use muscles to move their fins and tails.
D)the streamlined shapes and nonstick surfaces of aquatic animals reduce resistance due to drag.

Question

Quizplus · Accepted Answer

The streamlined shapes and nonstick surfaces of aquatic animals reduce resistance due to drag, allowing them to expend less energy to move than walking or flying animals. Water does provide less resistance than air, but this alone does not explain why aquatic animals require less energy to move. Gravity does not have more impact on aquatic animals than it does on terrestrial animals, as both are subject to the same force of gravity. Aquatic animals do in fact use muscles to move their fins and tails, but the streamlined shapes and nonstick surfaces of their bodies reduce the amount of energy required to do so.

Animals That Swim Expend Less Energy to Move Than Do