THE mystery of how dolphins and seals can hear without external ears has been
solved. They are 鈥渁coustic fatheads鈥�, says Darlene Ketten of the Woods Hole
Oceanographic Institution in Massachusetts. 杏吧原创s have long debated how
some marine mammals, with nothing more than pinprick holes for ears, can collect
sounds and conduct them to the middle and inner ears, deep in their heads. Many
suspected facial fat, but couldn鈥檛 explain how the fat conducted sound.
Ketten used computerised tomography and magnetic resonance imaging to examine
the fat bundles in the lower jaws and ear canals. 鈥淭hese fats have a shape like
an ear trumpet,鈥� she told a meeting of the Society for Marine Mammalogy on Maui,
Hawaii, earlier this month.