Which term defines an animal whose body temperature is regulated by the environment?

Which term defines an animal whose body temperature is regulated by the environment?

• A. Vertebrate
• B. Reptile
• C. Scales
• D. Cold-blooded

Answer: (D)

Body temperature regulation splits between animals that generate heat internally and those that rely on the environment. When an animal’s body temperature largely follows the surrounding conditions, we describe it as cold-blooded. This term captures the idea that heat comes from outside rather than being produced by metabolism, so their warmth isn’t kept constant across environments. Reptiles, amphibians, and many fish are typical examples, often basking to warm up or seeking shade to cool down. In contrast, vertebrate is a broad group that includes animals with backbones and spans both cold- and warm-blooded species, so it isn’t specific to how temperature is regulated. Scales are just a body covering, not about heat management. A reptile is commonly cold-blooded, but not all cold-blooded animals are reptiles, since fish and amphibians are also included.