Frogs are ectotherms, this means they get their heat
from external sources. They are sometimes called 'cold
blooded', but in fact they do not have cold blood, it
is just regulated by their environment. In comparison,
humans are endotherms and can maintain their body temperature
at about 37°C.
Frogs can control their temperature with their bodies,
for example by changing their color to affect how much
solar radiation (heat from the sun) they recieve, or
absorbing or evaporating water through their skin.