R & C | MAMMALOGY

Heyning, J. E. and J. G. Mead, 1996. Suction feeding in beaked whales: Morphological and experimental
evidence. Contributions in Science. No. 464, 12 pp. Natural History Museum of Los Angeles County.

Abstract:

Beaked whales possess several unique morphological features of the head. In most species, females and juveniles lack erupted teeth; the erupted teeth of adult males are used primarily for intraspecific fighting. All beaked whales possess one pair of throat grooves. Several authors have hypothesized that some toothed whales may capture prey primarily by suction. To test this hypothesis, we dissected a series of beaked whales and other cetaceans to ascertain the functional morphology related to this mode of feeding. The throat grooves of beaked whales allow for expansion of the gular region. A layer of loose connective tissue between muscle groups in the floor of the mouth allows the tongue to move freely as it is retracted posteriorly by the contractions of the hyoglossus and styloglossus muscles. The combined effects of tongue retraction and gular floor distention appear to function to create a sudden drop in intraoral pressure allowing beaked whales to suck in prey items. The relatively large hyoid bones provide the origin for several large gular muscles that control the tongue and the floor of the mouth. Observations of live animals corroborate the anatomical findings that beaked whales use suction to acquire prey.