DO FISH TALK.

Hawera Star, Volume XLVIII, 22 October 1924, Page 3

DO FISH TALK.

EXPERIMENTS AT THE ZOO. Do fish live in a soundless world, or can they make audible signals ? Some interesting preliminary experiments have just been made in the aquariam at the London Zoo. with an Admiralty pattern hydrophone to which was attached a three-valve amplifier (say 6 the Daily News). The hydrophone, whose normal function is to detect the approach of submarines, is so delicate that on one occasion during the war a succession of sounds was too painful to bear, and the telephones had to be removed from the ears. Comparing times later on, it was found that the noises were caused by the explosion of depth charges .46 -miles away! This device was. dropped into the tank where live the wrasse—boldly decorated sea fish with enviable appetites. There was a- rushing noise, which was traced to the apparatus for aerating the water. When small' crabs were tfirown to the wrasse one heard a series of sharp clashes, clearly due to the snapping jaws of the fish. With the crayfish there was a painful clangour wlven one of these lobster-like creatures actually “fingered” the hydrophone. Carp gave swishes and very faint “plops” as they took pieces of' chop-ped-up meat, while the trout went into instant retirement when the microphone was lowered into their tank. They never stirred a cautious fin until it was removed. Each tank gave a different basic tone. Now aiid then one imagined that there were distinctive 1 sounds something like buzzes, and again there was a noise (with the crayfish) like the snapping of a watch-ca*e, hut these might have been electrical in their origin. The question whether fish emit sounds (apart from feeding noises) cannot be solved in an hour or so. A series of tests to find the best water microphone is clearly necessary, as well as an immense amount of patient listening • after the fish have become used to the presence of the instrument. Only four tanks out of 95 were visited at the first test, and the other 91 may hold further secrets.

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