Photo credit: Jackie Hildering

How do whales lose excess heat?

We'd like to share a great question put to us from a young girl.  She wondered how whales got rid of extra heat; did they pant, did they sweat?

This is a particularyly enlightened question, especially for a child, since it reflects that knowedge that whales are mammals that are warm-blooded and that must, therefore, be able to maintain a constant internal temperature.

The whale-like marine mammals (cetaceans) do not sweat or pant.  They lose heat by controlling how much blood flows through their fins.  The fins are not as insulated as the rest of the whale's body since hte fins are not covered with blubber.  If cetaceans need to shunt off heat, more blood goes into their fins and the heat is radiated out from the blood into the water.

This is also why you see sea lions with their pectoral fins in the air.  Their fins are also highly vascularised and without blubber, so when they dip them in the water and hold them up, the water evaporates and carries away more body heat.

The images show you the pectoral fins of a Steller sea lion and a mature male killer whale (A38; aka 'Blackney").