AP BIOLOGY

Detailed explanation-1: -ectotherm, any so-called cold-blooded animal-that is, any animal whose regulation of body temperature depends on external sources, such as sunlight or a heated rock surface. The ectotherms include the fishes, amphibians, reptiles, and invertebrates.

Detailed explanation-2: -In vertebrates, endothermy is typically associated with birds and mammals while fishes, amphibians, and reptiles are generally typified as ectotherms.

Detailed explanation-3: -Amphibians and reptiles are well-known for being ectothermic (cold-blooded). This means that they are unable to internally regulate their body temperature, and instead they rely on their external environment to do so.

Detailed explanation-4: -By and large (with more than 8, 000 species, there are exceptions to almost every rule), reptiles are ectotherms. That is, they rely upon ambient thermal heterogeneity to regulate their internal temperatures-for example, by basking in sunlight to become warm, and moving to shade to cool down.

Detailed explanation-5: -Most fish are ectotherms. Ectothermy can be metabolically more efficient than endothermy because organisms do not have to expend any energy to self-regulate their body temperatures.