The circulatory systems of bony fishes, rays, and sharks are most similar to ________.
A) those of birds, with a four-chambered heart
B) the portal systems of mammals, where two capillary beds occur sequentially, without passage of blood through a pumping chamber
C) those of reptiles, with one pumping chamber driving blood flow to a gas-exchange organ, and a different pumping chamber driving blood to the rest of the circulation
D) those of sponges, where gas exchange in all cells occurs directly with the external environment
E) those of humans, where there are four pumping chambers to drive blood flow

Question

Quizplus · Accepted Answer

Bony fishes, rays, and sharks have a single-loop circulatory system with a two-chambered heart, similar to the portal systems of mammals where blood passes through two capillary beds in sequence. This is unlike the four-chambered hearts of birds and humans, the more complex circulatory systems of reptiles, or the direct environmental gas exchange seen in sponges.

The Circulatory Systems of Bony Fishes, Rays, and Sharks Are