Frogs - AK

Frogs are ectotherms. Ectotherms are organisms that are not able to increase respiration rates to generate heat internally. They rely on external sources of heat to regulate their body temperature.

Frogs posses many behavioural and physiological adaptations in order to regulate their body temperature. To keep warm frogs bask in sunlight on top of rocks. They may undertake many changes in order to cool off

Moving To The Water
Frogs such as leopard frogs (Rana sphenocephala) and green frogs (Rana clamitans) retreat to water when they become too hot. As the water is significantly cooler than the air it will help cool the frogs through conduction. In addition to this water rehydrates the frogs allowing them to use evaporative cooling

Evaporative Cooling
At high temperatures water starts to evaporate from a frog's skin producing a cooling effect. As long as a frog has access to water it can usually adapt to reasonably high temperatures making moisture and humidity vital to a frog's survival.

Frogs such as monkey frogs (Phyllomedusa sauvagei) that live far far from water have developed special adaptions. They produce a waxy secretion that helps prevent water from evaporating. These frogs allow their body temperatures to track the air temperature until they reach about 37.7 degrees Celsius. At this point, the frogs’ bodies exhibit accelerated evaporation, which keep their body temperatures from rising any higher. Then the frogs must find water and rehydrate to recover after periods of excessive evaporation.

Retreating To Shelter
An overheated frog may also simply move out of sunlight and to a cooler, more sheltered location. Terrestrial frogs such as spadefoot toads (Scaphiopus holbrokii) may dig a burrow or bury themselves in the leaf litter. Green tree frogs (Hyla cinerea) and other arboreal species may hide under tree bark or inside a tree hollow to escape high temperatures. Some frogs that live in seasonally hot or dry regions may retreat to a shelter for months at a time, this is called aestivation. While aestivating, some frogs produce a mucous cocoon or retain their shed skin to slow water loss. When an aestivating frog feels the soil or leaf litter’s moisture content rising, the creature starts to become active again.

Colour Change
As dark coloured animals tend to warm up quickly and light coloured animals cool off more quickly, the colour of a frog can be important to it's thermoregulation. Some frog species are able to change their color or pattern, and though this undoubtedly allows them to better hide from predators, scientists suspect that most species also use their colour-changing abilities to thermoregulate. Species such as the Pacific tree frog (Hyla regilla), grey (Hyla versicolor) and White’s tree frogs (Litoria caerulea) have been documented to change color because of ambient temperatures.