Sea Creatures

Most sea creatures, from whales and dolphins to fish, sharks, shrimps and possibly even anemones, respond to sound, and many can produce it. They use it to hunt and to hide, find mates and food, form and guide shoals, navigate 'blind', send messages and transmit warnings, establish territories, warn off competitors, stun prey, deceive predators, and sense changes in water and conditions. Marine animals click bones and grind teeth; use drum-tight bladders and special sonic organs to chirp, grunt, and boom; belch gases; and vibrate special organs. Far from the 'silent deep', the oceans are a raucous babel. Into this age-long tumult, in the blink of an evolutionary eye, has entered a new thunder: the throb of mighty engines as 46,220 large vessels plow the world's shipping lanes. Scientists say that background noise in the ocean has increased by roughly 15 decibels in the past 50 years. It may not sound like much overall, but it is enough, according to many marine biologists, to mask the normal sounds of ocean life going about its business.