Definition

Noun: * An animal whose internal body temperature changes significantly and matches the temperature of its surrounding environment. These animals are often called "cold-blooded" and rely on external heat sources to regulate their body temperature. This group includes all animals except for birds and mammals.

Usage

• The term is used in scientific contexts, particularly in biology, zoology, and ecology, to classify animals based on their thermoregulation.
• It describes an animal's physiological state, not its behavior.
• Example: "Reptiles, amphibians, and fish are all poikilotherms."

Examples

• "A lizard basking on a rock is a classic example of a poikilotherm regulating its body temperature behaviorally."
• "The metabolic rate of a poikilotherm increases as the environmental temperature rises."
• "Unlike endotherms, poikilotherms do not use metabolic energy to maintain a constant internal temperature."

Advanced Usage

• Poikilothermic (adj): Describing the condition of having a variable body temperature.
  • Example: "Snakes exhibit poikilothermic physiology."
• The term is often contrasted with homeotherm (an animal that maintains a constant internal body temperature).

Variants and Related Words

• Poikilothermy (n): The state or condition of being a poikilotherm; having a body temperature that varies with the environment.
• Ectotherm (n): A closely related and often synonymous term. While all poikilotherms are ectotherms, some biologists make a subtle distinction, with "ectotherm" emphasizing the source of heat (external) and "poikilotherm" emphasizing the result (variable temperature).
• Cold-blooded (adj, informal): The common, non-scientific term for poikilothermic animals.

Synonyms

• Ectotherm
• Cold-blooded animal (informal)

Antonyms

• Homeotherm
• Endotherm
• Warm-blooded animal (informal)

Noun

1. an animal whose body temperature varies with the temperature of its surroundings; any animal except birds and mammals