Ocean Sports Whale Fact of the Day: Why would a Humpback stick a body part out of the water and up into the breeze? During prolonged movement in warm water, a Humpback’s body will generate heat (the same thing happens to you when you’re exercising, but you’ll start sweating to cool down). Since Humpbacks don’t have sweat glands, but do have some control over their circulatory systems, as they heat up, they can direct blood flow into a network of capillaries near the surface of the their flippers, flukes and dorsal fin: in Latin these capillaries are called “rete mirabilis” which translates to “miracle network”. This in turn allows their excess body heat to be shed to the external environment through evaporation and convection. Many researchers believe that whales who are resting with their flukes exposed vertically in the air, or who are lifting their pectoral flippers for prolonged periods of time in the air, are actually trying to cool off.