Bumblebee Heat Regulation
While flying,bumblebees have a body temperature that is generally well above that of the air around them,and tends to be constant at about 35 C.Keeping warm is harder the smaller you are. Small creatures,like bees,have a vast surface area relative to their volume,and lose heat incredibly quickly.Yet bumblebees can keep themselves warm even when the surrounding air is 30C cooler than their body temperature.Scientist Bernd Heinrich found that the answer to bees’ability to retain heat is in two parts:keeping heat in, and generating it in the first place.Keeping warm is helped if you have insulation,and of course bumblebees have furry coats.The vital thing for a bumblebee is to keep its thorax (the middle section)warm, because this is where the flight muscles are;unless the thorax is warm enough,the muscles cannot contract sufficiently fast,and the bee cannot take off.The temperature of the abdomen does not matter much in flight.The abdomen and thorax in a bumblebee are connected by a very narrow waist,and the front part of the abdomen contains a sac of air,so heat loss from the thorax to the abdomen is minimal (air is a poor conductor).A bumblebee’s heat is generated by the contractions of the flight muscles.In flight a bumblebee flaps its wings 200 times per second.This generates a lot of heat,but of course comes at a cost:bumblebee flight is enormously expensive in terms of the energy that it uses.Consequently,bumblebees have to eat almost continually to keep warm.
