Squid listen?

This is the question posed by marine biologist Aran Mooney, from the Woods Hole Oceanographic Institute (WHOI) in Massachusetts (USA), and his colleagues. To find out they worked withsquid of the species Loligo pealeiThey were placed in tanks of water, previously anesthetized, and connected with electrodes to detect the signals sent to the brain. In addition, submersible speakers were introduced into the tanks to reproduce sounds in the water. Experiments showed that this animalcan hear low-frequency sounds between 30 and 500 Hz. This means that squids are able to hear the sounds of the reefs, the wind, the waves, but not the high-frequency echolocation signals emitted by dolphins and other of their natural predators. The findings were published in the journalThe Journal of Experimental Biology.

Squid’s sense of hearing does not detect pressure changes produced by sound waves in the air, as occurs in land animals. On the contrary, Mooney assures that the “ear” of these marine cephalopods detects its own movement within the sound wave, and compares it to a fruit suspended in jelly. “If you make the jelly shake, the fruit moves too,” he explains. Squids havetwo organs called statocysts, located at the base of the brain, which bear a curious similarity to the cochlea of the human ear. Each statocyst consists of a hollow fluid-filled sac with hair cells. On the outside of the sac, hair cells are connected to nerves, which in turn communicate with the brain.

Mooney now also wants to investigate whether the growing cacophony of human-generated sounds in the ocean affects squid behavior and threatens its survival. “The sound of the ocean is rising“Mooney said.” Commercial shipping, oil and gas exploration make a lot of noise. And we don’t know how it can affect mollusks unless we know what they hear. “