USA Biology Olympiad (USABO) Practice Exam

How does the anatomy of an animal from a cold climate differ from that of an animal from the tropics?

1. The animal from the cold climate has larger ears

2. The animal from the cold climate has smaller ears

3. The animal from the cold climate has longer tails

4. The animal from the cold climate has thicker fur

The correct answer is: The animal from the cold climate has smaller ears

Animals that inhabit cold climates often possess anatomical adaptations that help them conserve heat. One such adaptation is the size of their extremities, such as ears. In cold environments, animals tend to have smaller ears compared to those in tropical regions. This reduced ear size minimizes the surface area exposed to the cold air, thereby reducing heat loss from the body. In contrast, animals from warmer, tropical climates typically have larger ears, which facilitate heat dissipation. Large ears can help increase blood flow to the skin, allowing these animals to release excess heat more effectively. Thus, the anatomical adaptations of animals in cold climates, including smaller ears, serve a crucial role in thermoregulation, making this answer the most appropriate choice in understanding how anatomy reflects environmental adaptations.