Ectotherm

An ectotherm (from Ancient Greek ἐκτός (ektós) 'outside' and θερμός (thermós) 'heat'), more commonly called a "cold-blooded animal", is an animal that does not create much heat inside its body to keep warm. Instead, it uses heat from the world around it. This helps the animal use energy efficiently. Animals like frogs are ectotherms.

Some ectotherms live where the temperature stays almost the same, like in the deep ocean. These can be thought of as homeothermic ectotherms. In places where the temperature changes a lot, many animals, such as reptiles, find ways to control their temperature. For example, they may sit in the sun to get warm or find shade to cool down.

Unlike ectotherms, endotherms make most of their heat from inside their bodies using their own energy. Mesotherms use a method that is in between these two.

Because animals use more than just two ways to control their temperature, words like warm-blooded and cold-blooded are not used much in science anymore.

Adaptations

See also: Insect thermoregulation

Ectotherms, or cold-blooded animals, have special ways to help control their body temperature. Reptiles and many insects warm up by finding sunny spots and positioning themselves to get the most sunlight. When it gets too hot, they look for shade or cool water. In cold weather, honey bees stay warm by clustering together. Butterflies and moths can warm up by holding their wings in a way that catches the sun’s heat before they fly. Some caterpillars stay warm by grouping together.

Ectotherms also have body changes that help with temperature control. Diving reptiles keep warm by letting cold blood near their skin pick up heat from warmer blood inside their bodies. Bullfrogs cool down by making extra mucus on their skin when it’s hot. During very cold times, some ectotherms go into a resting state called torpor, where their body processes slow down. Reptile owners sometimes use special ultraviolet lights to help their pets warm up.

The article mentions a few specific animals and terms:

• forest tent caterpillar
• fall webworm
• endothermically
• poikilothermy
• homeothermy
• heat exchange
• torpor
• wood frog

Pros and cons

See also: Ambush predator

Ectotherms, often called cold-blooded animals, use heat from outside their bodies to stay warm. They rely on things like sunlight to reach the right body temperature for moving around and doing things. Unlike warm-blooded animals, which make their own heat inside their bodies, ectotherms depend on their surroundings to control their temperature.

Because ectotherms need outside heat, they are usually more active during the day when the sun is out. Some, like certain lizards, are nocturnal and wait quietly to catch their food without using much energy. This helps them go for long times without eating, unlike warm-blooded animals, which need to eat often to keep their body heat.