An endotherm is an animal that generates most of its body heat internally from metabolic reactions and keeps its core temperature fairly constant, whatever the temperature of the surroundings. Mammals and birds are endotherms.
Endotherms have a high metabolic rate. Much of the energy released in respiration is lost as heat, and this heat keeps the body warm. They can also adjust their heat production and heat loss physiologically, for example by shivering or sweating.Advantages
• A constant core temperature near the optimum for their enzymes, so metabolism runs at a steady, fast rate.
• They can stay active when the environment is cold, including at night and in winter.
• They can live in a wide range of habitats, including polar and high-altitude regions.
• They can respond quickly (for example, to escape a predator) without first having to warm up.Disadvantages
• A large proportion of the energy from food is used to generate heat, so endotherms need much more food than ectotherms of the same mass.
• Less energy is left over for growth and reproduction.
• Small endotherms have a large surface area to volume ratio, so they lose heat quickly and must eat very often. A shrew, for example, must feed every few hours.For example, a mouse and a lizard of similar mass live in the same place. The mouse needs several times as much food energy each day, because most of it is spent keeping warm, but it can forage on a cold night when the lizard cannot move.
Endotherms have a high metabolic rate. Much of the energy released in respiration is lost as heat, and this heat keeps the body warm. They can also adjust their heat production and heat loss physiologically, for example by shivering or sweating.Advantages• A constant core temperature near the optimum for their enzymes, so metabolism runs at a steady, fast rate.
• They can stay active when the environment is cold, including at night and in winter.
• They can live in a wide range of habitats, including polar and high-altitude regions.
• They can respond quickly (for example, to escape a predator) without first having to warm up.Disadvantages
• A large proportion of the energy from food is used to generate heat, so endotherms need much more food than ectotherms of the same mass.
• Less energy is left over for growth and reproduction.
• Small endotherms have a large surface area to volume ratio, so they lose heat quickly and must eat very often. A shrew, for example, must feed every few hours.For example, a mouse and a lizard of similar mass live in the same place. The mouse needs several times as much food energy each day, because most of it is spent keeping warm, but it can forage on a cold night when the lizard cannot move.