Page 88 - Design in Nature
P. 88

SONAR INSIDE A DOLPHIN'S SKULL


                A dolphin can distinguish between two different metal coins under
           water in complete darkness and up to 2 miles (3 kilometres) away. Does it
           see that far? No, it does this without seeing. It can make such accurate
           determinations by means of the perfect design of an echolocation system
           inside its skull. It gathers very detailed information on shape, size, speed
           and structure of near objects.
                It takes some time for a dolphin to master the skills needed to use such
           a complicated system. While an experienced adult dolphin can detect most
           objects through a few signals, a juvenile has to experiment for years.
                Dolphins do not use their echolocation just to detect their
           surroundings. Sometimes they group during feeding and emit high-pitched
           sounds so powerful that they dazzle their prey, which are then ready to be
           picked up. An adult dolphin produces sounds inaudible to humans (20,000
           Hz. and above). The focusing of soundwaves is done in several areas of the
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