What physiological adjustment does the jackrabbit’s circulatory system make during hot days?

The jackrabbit’s circulatory system primarily increases blood flow to the ears during hot days as an adaptive mechanism to help regulate body temperature. The large, vascularized ears of jackrabbits play a crucial role in thermoregulation. By increasing blood flow to these ears, the jackrabbit can dissipate excess body heat through convection and radiation, effectively cooling the blood before it circulates back to the core of the body.

This adaptation is significant for a desert-dwelling animal, allowing it to maintain homeostasis in an environment with high temperatures. It ensures that the rabbit can remain active and avoid overheating while foraging for food or evading predators.