For decades, scientists could not understand how dolphins could swim at the speed of nearly 40 kilometers an hour. The animals simply did not have enough muscle, the scientists thought. But dolphins have a secret, part of which lies in their blubber, a complex substance also found under the skin of porpoises, whales, and other marine animals
Blubber is a thick, dense layer of highly organized connective tissue with a lot of fat cells. It covers practically the whole creature, and it is strongly attached to the musculature and skeleton by highly organized, fan-shaped networks of tendons and ligament. These networks, in turns, are composed of elastic fibers and collagen, a protein that is also found in skin and bones. Blubber, therefore, is much more than a layer of insulating fat. It is a highly sophisticated combination of various living tissues.
How, though, does blubber help dolphins and porpoises to swim so fast –Dall’s porpoises at speeds of up to 56 kilometers an hour? For one thing, blubber gives the animals a more streamlined shape. For another, the blubber between their tail flukes and dorsal fin is crosshatched with an especially dense array of collagen and elastic fibers –a design that gives the tail elasticity and stores mechanical energy. Hence, when muscles move the tail in one direction, the blubber, like a spring, helps to pull it back, thus both adding thrust and conserving energy.
Blubber also aids buoyancy and provides thermal insulation. Its fat content stores energy for lean times. Understandably, this versatile composite has attracted the interest of those who are trying to improve the efficiency of marine craft and their means of propulsion.