Scientists: squid can hear


09/02/2011

Scientists in the United States revealed the mystery of whether the squid and hear how it goes. Marine biologist Eyren Mooney (T. Aran Mooney), a scientist Oceanographic Institution, Woods Hall (WHOI) in Massachusetts, measured the nerve impulses produced in response to the sounds of sea animal. Under the skin of squid were implanted electrodes to determine the nerve signals from the statocysts, two sensory organs like the bag near the bottom of the animal brain.

Longfin squid (Loligo pealeii) were placed in the tank, where they were anesthetized with magnesium chloride, and were at the time of action of the horn (the type used to synchronize swimmers), which was used to play the sounds.

The findings confirm that squid can hear low-frequency sounds is between 30 and 500 Hz, but with the proviso that the water temperature should reach at least 8 C. Dr Mooney said the squid probably able to hear the waves, the sound of the reef and the wind on the surface of the water, but not able to hear high-frequency sounds such as echo-location signals emitted by toothed whales and dolphins, which are the main predators of squid.

Unlike terrestrial animals, the squid do not hear through the detection of pressure changes produced by the sound waves, and feels moving waters that are sound. Dr. Mooney also said the squid mostly hears, finding himself moving with the sound wave, and compared the process with a piece of fruit, are in jelly. He said that if you make a move, forcing the jelly wobble, the fetus moves in the same way as jelly.

Statocysts - it is fluid-filled sacs that contain hair cells. A small grain of calcium carbonate, called the otolith is also present in each statocyst. In response to a motion made by the sound of hair cells relate statoliths and generate signals that are sent to the brain. The hair cells in the statocyst of squid are similar to the hair cells in the cochlea in human ears that convert vibrations in the air into signals that are sent to the brain.

The research paper was published in the Journal of Experimental Biology. Researchers have now begun to study a relatively simple sensory organ squid to determine whether it can shed light into the evolution of hearing in the higher animals. Dr. Mooney also hopes to explore the effect of "the burgeoning cacophony of human-generated sounds in the ocean," to see whether it affects the behavior of the squid and it threatens their survival.

Original: Physorg Translation: M. Potter


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