Thermo-regulation in frogs

Frogs are ectothermic amphibians who are unable to regulate their temperatures internally like birds or mammals. Instead they need to warm up using other things outside their bodies- this action is called thermoregulation. Ectotherms use behavioural mechanisms to control their body temperatures.

If a frog is too hot, it may retreat to water. The water is cooler than the air and does not only cool the frog through conduction but also rehydrates it, which allows it to use evaporative cooling to stabilise its body temperature- when temperatures are high, water evaporates from the skin of frogs, which produces a cooling effect therefore, as long as they have access to water, they are able to adapt to high temperatures. This is why moisture and humidity are vital for a frog’s survival.

Another solution to cool down is to move to shelter in a cooler and more sheltered location. Terrestrial frogs such as Spadefoot Toads may dig a burrow or bury themselves in litter. Green tree frogs hide under tree bark or inside a tree hollow in order to cool down.

Some frogs undergo aestivation, which is like a period of dormancy- it is defined as a state of reduced metabolic activity in warm or dry periods whereby the frogs ‘sleep’ in a shelter for months at a time. While aestivating, some frogs produce a mucous cocoon or retain their shed skin to slow down water loss. When the frog feels the soil or leaf litter’s moisture content rising, it will start to become active again.

Frogs hibernate to escape the freezing temperatures of winter. Their heartbeats and breathing slow, their body temperature drops to nearly match the outside temperature, and they pass the time in a state of dormancy. Aquatic frogs hibernate under water and take in oxygen from the water through their skin. They spend most of the winter lying on top of the bottom's mud or partially buried in mud. At times, they may even slowly swim around. Terrestrial frogs normally hibernate on land. Spring peepers, for example, are not adept at digging; instead they find deep holes or cracks in logs or rocks, or simply burrow down in the leaf litter as far as they can.

Some frog species such as the Tree Frog are able to change their colours or patterns in order to thermoregulate as darker coloured frogs tend to warm up more quickly and lighter coloured frogs cool off more quickly. When temperatures are cool, frogs need to bask in the sunshine to warm up enough to be able to move.

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