2 1 8 Compare Responses Of Named Australian Ectothermic And

The terms ectotherm and endotherm relate to the ability of an animal to regulate its body temperature. Ectothermic organisms rely on an external source – the environment – to provide them with heat energy (these include fish, amphibians and reptiles). Endothermic organisms rely on internal sources such as metabolic activity for heat energy.

In laboratory conditions the body temperature of ectotherms fluctuates over a wide range, as it is influenced by the ambient temperature. In nature, these organisms will alter their behaviour in order to maintain a relatively constant body temperature. In laboratory conditions the body temperature of endotherms tends to remain stable despite a variation in the ambient temperature. Endotherms have the ability to control its body temperature and maintain it in a stable narrow range. If the ambient temperature drop or increases above the animal’s tolerance range, endothermic animals can adjust their metabolic rate to control heat loss. In low ambient temperatures endotherms generate heat through increased metabolic activity, the size of the organism also plays a significant part – as smaller organisms lose heat faster and hence tend to have a higher metabolic rate. If the ambient temperature is high, an endothermic animal can alter the flow of blood near its surface which can cool the animal.


Ectothermic - The eastern brown snake: the eastern brown snake inhabits most dry and hot areas in Australia, along the eastern seaboard. Generally brown snakes are diurnal (awake during the day) however they may become active at night is the day temperature is too high. If the ambient temperature during the day is too high, the snake will seek shelter and become active in the cooler part of the day. If the ambient temperature drops below the optimum, the snake will bask in the sun in an attempt to gather heat energy.

Endothermic –The fairy penguin: fairy penguins have feathers which provide an insulating layer, trapping air close to the skin to reduce heat loss. In cold conditions these feathers are lifted away from the skin, providing a larger air layer and hence more insulation. In warmer conditions the feathers are pressed against the skin, reducing the air layer and providing less insulation.