Any cold-blooded animal—that is, any animal whose body temperature regulation is dependent on external sources, such as sunshine or a hot rock surface. Fishes, amphibians, reptiles, and invertebrates are all ectotherms. Endotherms, such as mammals and birds, can regulate their own body temperature internally. They do so by using oxygen consumption and heat production during exercise or when exposed to cold temperatures. Humans are an example of an endotherm.
Ectothermy is often used as a synonym for "cold-blooded," but this is incorrect. While all ectotherms must obtain their body temperature from outside sources, not all cold-blooded animals are ectotherms. For example, some insects (such as bees) are capable of regulating their body temperature using chaperone proteins within their cells. These organisms remain cold-blooded even though they aren't reliant on sunlight for body temperature regulation.
Ectothermy is more commonly used to describe animals that rely primarily on external sources for body temperature regulation. This may include animals that live in colder climates but have special adaptations (such as fur or feathers) that allow them to maintain a constant body temperature despite the fact that they are not exercising or exposed to direct sunlight. Ectotherms include most fish, reptiles, and amphibians; humans are an example of an ectotherm.
Ectotherms are creatures that keep themselves warm by absorbing heat from their environment. The body temperature of most ectotherms varies in response to variations in the ambient temperature. When the temperature drops, they slow down. When it rises, they speed up. This allows them to maintain a fairly constant body temperature.
Ectotherms can be divided into two main groups based on how they absorb heat from their environment: endothermic animals and heterothermic animals. Endothermic animals such as mammals and birds use their own internal heat to keep their bodies warm. Heterothermic animals such as reptiles and fish rely primarily on external sources for heat, sometimes using their internal heat to help out but mostly not. Fish, for example, can change the moisture content of their scales to adjust their skin temperature. This is called adaptive hypoventilation and it allows fish to control their body temperature more easily.
Endothermy is much more efficient at keeping an animal's body temperature stable than heterothermy. This is because heterothermic animals need to expend energy maintaining two different temperatures - one for blood cells and one for muscle cells. This is called "double-billing" and it makes them less efficient at using energy than endotherms.
However, heterothermy has some advantages of its own.
An ectotherm (reptile or amphibian) regulates its body temperature mostly through its surroundings. Endotherms (birds) can control their body temperatures by creating heat within their bodies. Ectotherms are the configurations of animal habitats. Endothermic animals need oxygen to burn energy produced by cellular respiration; this requires a large surface area in contact with air for effective heat loss or gain. Land mammals, including humans, are endothermic; they generate heat by muscle activity and lose it by radiation into the atmosphere and by conduction through their fur and skin.
Ectotherms are those organisms whose main method of regulating body temperature is via external factors such as sunlight, wind, and water. Animals in this category may be reptiles or amphibians. They include fish, birds, and mammals. Endotherms are those organisms that use internal sources to generate heat, such as metabolizing food into energy cells reserves that can be used later when energy is needed. Humans and other mammals are endothermic; we generate heat by metabolic processes and lose it by radiation into the atmosphere and by conduction through our fur and skin.
Endothermy is a term used to describe the mechanism by which organisms regulate their body temperatures. All endotherms must obtain their heat from an external source since they cannot produce it internally.
A cold-blooded animal, often known as an ectotherm, relies on external heat sources to control its body temperature. However, body temperatures within each species can vary based on a variety of reasons. In humans, women run cooler than men, and elderly people have lower body temperatures than younger people. Animals that are cold-blooded include reptiles, amphibians, fish, and birds.
Many plants and animals have evolved ways to control their body temperature. Some organisms with this ability are called endotherms because they derive energy from the environment instead of from food. Endotherms include mammals, birds, and some types of fish. Humans are an example of an endothermic organism. We derive our energy from both food and the environment, but most of us prefer to eat when we're not hungry and to sleep when we're not tired. This behavior is beneficial because it allows us to function at our best without getting sick or dying prematurely.
Some organisms such as bacteria, fungi, and algae are called heterotrophs because they extract nutrients from their surroundings. Heterotrophic organisms do not generate their own energy sources like plants and animals do. Instead, they obtain their energy from other organisms or substances in their environment. For example, bacteria use the sugar found in foods to make new cells and enzymes. Without these chemicals, bacteria would die quickly. Algae are another type of heterotrophic organism.