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			Communication in Marine Mammals Office of Naval Research 03.19.01 Marine mammals make and hear sound in different ways and for different reasons. The purpose of vocalizations ranges from communicating with the same species to locating unseen targets. Polar bears' hearing is as sensitive as human hearing. They make noise mostly when they are angry or threatened. Sounds include hissing, growling, champing of teeth, and soft chuffing. Cubs make noise by hissing, squalling, whimpering, lip smacking, and throaty rumblings. Polar bears also communicate through sight, touch, and smell. Sirenians have very small, hard-to-find ear openings. Their internal ear bones are very large and help provide a good sense of hearing. They communicate by making chirping, squeaking, and whistling noises. Pinnipeds make lots of different noises on land. Their sounds vary between sexes and ages. Sounds by breeding males are very loud, repetitive, and serve to threaten other males and advertise their high rank. Sounds can include barking, growling, yelping, and snarling. Female pinnipeds have a distinctive pup call, which helps a female recognize, locate, and maintain contact with her pup in crowded breeding colonies. Cetaceans produce two types of sound: one is for communication with other cetaceans and the other is to help them explore their environment. Both are produced as air moves in and out of nasal sacs. The most famous use of sound for communication between cetaceans is the song of the humpback whale. Cetaceans can explore their environment and objects in it through the use of echolocation. Echolocation is done by of sending out pulses of ultrasonic (the frequency is too high to be heard by humans) sound through the blowhole. When the sound waves bounce off objects in their path, a portion of the signal is reflected back. Features of the returning echo offer information about distance, size, shape, texture and material composition of an object. This system of sensing the environment is an advantage in orientation, navigation, and capturing prey in dark or turbid waters.


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