Diving and plunging through the waves to feed, some whales throw their jaws wide and engulf colossal mouthfuls of fish-laden water while other species simply coast along with their mouths agape (ram or skim feeding), yet both feeding styles rely on a remarkable substance in the whales' mouths to filter nutrition from the ocean: baleen. Alexander Werth from Hampden-Sydney College, USA, explains that no one knew how the hairy substance actually traps morsels of food. 'The standard view was that baleen is just a static material and people had never thought of it moving or that its function would be altered by the flow of water through the mouth', he says. Werth became fascinated with the substance during his postdoc days, when he worked with the Inupiat Eskimos of Barrow, Alaska, and decided to find out more about how the flexible material filters whale-sized mouthfuls of water. He publishes his discovery that baleen is a highly mobile material that tangles in flowing water to form the perfect net for trapping food particles at natural whale swimming speeds in The Journal of Experimental Biology at http://jeb.biologists.org.
Explaining that baleen is composed of keratin the same protein that makes hair and fingernails Werth also describes how the protein forms large continually growing plates, each with an internal fibrous core sandwiched between smooth outer plates. Whales usually carry 300 of these structures on each side of their mouths arranged perpendicular to the direction of water flowing into the mouth and Werth explains that the plates are continually worn away by the tongue to form bristly food-trapping fringes on the tongue-edge of each plate. In addition, the baleen fringes of the skim-feeding bowhead whale's bristles are twice as long as the lunging humpback's. Having obtained baleen samples from the body of a stranded humpback during graduate work at the New England Aquarium
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The Company of Biologists