ectotherms

Both amphibians and reptiles are ectotherms, meaning that they derive heat from the environment, rather than producing it internally.

Amphibian 2008

As “ectotherms” they depend on the external environment to control their body temperature.

Lizards are in Danger of Extinction from Global Warming? | Impact Lab 2010

Generally, sea surface temperatures in the Arctic are low, but true ectotherms (previously called "cold-blooded organisms", i.e., their body temperatures vary with the temperature of their surroundings) can grow at the freezing point of seawater.

Physical factors mediating ecological change in the Artic 2009

The high diversity of Late Maastrichtian dinosaurs in high latitudes, where ectotherms are absent, strongly questions hypotheses according to which dinosaur extinction was a result of temperature decline, caused or not by the Chicxulub impact.

Neoceratopsian publications for 2008 ReBecca Foster 2009

Fish are ectotherms, thus, for the most part, their body temperature is governed by that of the surrounding waters.

Information required to project responses of arctic fish 2009

Endotherms differ from an ectotherm because they typically have core temperatures above that of the surrounding environment, whereas the core temperatures of ectotherms depend on external sources of heat – primarily from solar radiation.

Endotherm 2008

Many ectotherms are able to regulate their body temperature behaviorally, by moving into and out of sunlight.

Endotherm 2008

Some mammals and birds that at times have high and well-regulated body temperatures, but at other times they are more like ectotherms and are referred to as heterotherms (Greek hetero = different).

Endotherm 2008

Endotherms such as mammals maintain a preferred body temperature with heat generated by their own metabolic processes, while ectotherms such as lizards obtain their body heat from the environment.

Fundamental principles of energy 2008

For example, the body temperature of a small tropical fish in warm water or desert lizard on hot sand (both of which are considered ectotherms) may have body temperatures higher than birds or mammals in the same environment-largely because of the insulation provided by feathers and fur and associated behavioral and physiological heat-dissipating mechanisms that prevent their body temperatures from increasing above critical temperatures.

Endotherm 2008