Beluga whales have a loose, fatty region on top of their head, called a melon, that is critical for echolocation.
The head of a beluga whale is dominated by the melon, a fat filled area on top of the frontal portion of the whale’s skull that obscures the rostrum, or upper jaw. It is critical to focusing and projecting echolocation signals and is the means by which the sounds a beluga makes are ultimately projected to the water.
The melon can function as an “acoustic lens,” focusing sound into a beam the way a flashlight’s lens and reflector focus light. Belugas have the ability to change the physical shape of their melon, which may allow them to control sound transmission.
The fat composing the melon is distinct; it cannot be broken down to produce energy, indicating its importance.
Sources: (AMMPA, 2014, 2017; Bonner, 1989; Cranford, Amundin, & Norris, 1996; Frankel, 2008; Pabst, Rommel, & McLellan, 1999; Paine, 1995; Reeves, Stewart, Clapham, & Powell, 2002; Williams, 2002)
Image: Steve Snodgrass