Morphology and lipid biochemistry of fats associated with cetacean ears

Thursday, March 22 , 2012
Redfield Auditorium - 12:00 Noon
Ms. Maya Yamato
Ph.D. Candidate, Joint Program in Biological Oceanography

Cetaceans possess highly derived auditory systems adapted for underwater hearing.  Toothed whales receive sound through specialized fats associated with the lower jaws, leading to the ears.  These “acoustic fats” have very unusual chemical compositions, comprised of endogenously synthesized short, branch-chained fatty acids and fatty alcohols within triacylglycerols and wax esters.  These acoustic fats and hearing mechanisms in toothed whales are relatively well-studied.  In contrast, virtually nothing is known about hearing in baleen whales.  Here, we report the discovery of a large, well-formed fat body which contacts the ears and ossicles of at least two baleen whale species, the minke whale (Balaenoptera acutorostrata) and fin whale (Balaenoptera physalus).  We compare the morphology and biochemical composition of these newly described fat bodies with the acoustic fats of several toothed whale species, including the bottlenosed dolphin (Tursiops truncatus), harbor porpoise (Phocoena phocoena), beluga whale (Delphinapterus leucas), and pygmy sperm whale (Kogia breviceps).