September 3, 2012 14:37
When night falls in the thick rainforest of El Yunque in the north-east of Puerto Rico begins deafening concert: every living creature seeks to assert itself.
In the early 1980s, Peter Narins of the University of California in Los Angeles (USA) heard in the forest at all other sounds — using geophones. Underground was quieter, but not quiet. So scientists could discover that spotted whistler (Leptodactylus fragilis) are able to communicate by sending seismic signals.
These frogs emit a series of short beeps (about four per second), inflating and blowing vocal sac under the jaw. Usually they do it, sticking out of the mire only head and front paws. Therefore, expanding bag, beating on the ground.
The frequency of such emerging seismic trapped relevant sensory cells. Mr. Narins drew attention to the fact that when the male hears call of another male, he is silent. Perhaps the vibration of the Earth have the same effect? Scientists have collected hornblende from parts of the typewriter, and found that this question should be answered in the affirmative. If a frog does not feel shaking under your feet, it does not stop.
For the first time this kind of communication was observed in vertebrates. Since that has been three years, but it is still unclear why he was spotted Whistler. It seems logical to assume that such males are assessing the distance to the nearest competitor.
But recent studies have shown that many species of the animal kingdom receive and transmit information in a way. And this is one of the most common means of communication. For example, Damien Elias of the University of California at Berkeley (USA) is studying the tactile alarm in spiders, horses. He found that their vibration signals are incredibly complex and in many ways: spiders can drumming body parts on the ground, rubbing one part of the body of another, or use special vibrating bodies.
Songs of these males are not only beautiful, but also functional. When Mr. Elias glued wax body mounts that help produce these signals, females often eat such males, rather than mate with them. This is true for the wolf spiders.
Mr. Elias confident that ultimately seismic connection is detected in the majority of small creatures, because they, in his words, it is simpler to vibrate the ground than the air, the more noise in the air without them missing.
But seismic talk attracted not only kids. In the late 1990s, Caitlin O'Connell-Rodwell of Stanford University (USA), said that the African elephant from Namibia sometimes freeze, lean forward, keep your ears parallel to the body and pick up one of the front legs. And soon after that always arrive or group of elephants or swept car.
After some time, the researcher learned to recognize seismic signals indicating the approach of a predator. When she passed them, the elephants just leaned forward, freeze, were divided into family groups and left the hectic place.
Moreover, vibrotactile and people have said Ms O'Connell-Rodwell, although we are not as sensitive as the elephants. Only the deaf freed auditory cortex takes over the function of the signal processing of this kind.