Communication in dolphins
Dolphins have developed a very complex communication system. They communicate with each other in order to get important messages to one another, to organize their hunt and even to find out about found objects.
Types of communication
Whistles
At the whistle the question arises, how do the dolphins manage to create a sound? Since dolphins dive to a depth of 800 meters, the whistle would have to get higher and higher with increasing depth, because whistles are usually caused by vibrations in a cavity. If this cavity is compressed by increasing water pressure, the tones become higher and higher and become unusable as a means of communication. For this reason, scientists put forward the thesis that the dolphins do not use signature whistles at all, but instead use their vocal cords to generate completely normal sounds. The advantage of this type of sound generation would be that such sounds are created due to vibrating tissue, so that increasing water pressure would no longer be a problem. To test this thesis, researchers made an experiment in which they put a mask on a dolphin through which it was given heliox to breathe. Heliox is a mixed gas that is often used as breathing gas during dives. It consists of 80 percent helium and 20 percent oxygen. If the signature whistle is actually a whistle, its frequency would have to increase significantly. But she didn't. The gas had the same effect on the whistle as the water pressure at a depth of 900 meters: namely nothing.
Jumps
Dolphins jump out of the water to communicate over distances of more than 90 meters. They use a very sophisticated system that is comparable to our letter system. Individual jumps are combined to form a message. The dolphins use around 30 different jumping figures. Usually two to three jumps are combined. The movement pattern “jump spy” consists of three figures: “stop”, “point” and “head”. In the 1930s, the American scientist George K. Zipf examined the frequency of the various jump figures and compared it with our language. He was able to find a striking resemblance. Very complex jumps are used very rarely, while easy jumps can be found every third jump. Complicated movement patterns are firstly more difficult and secondly also much more energy-consuming and therefore cannot be shown by the dolphin that often.
Body contact
Communication through touch is used on the one hand to exchange tenderness, but on the other hand to organize oneself while hunting. Because the dolphins cannot use their usual whistling sounds and jumps when hunting in order not to startle the prey, they communicate here via body contact. Communication via body contact is also used in the complex hunting system of the black dolphins. First the hunted prey is rounded up by the dolphin school, and then only one animal at a time swims into the shoal of fish and catches prey. When asked who should swim in the school of fish and catch prey, the dolphins do not use the usual whistle signal, as they do not want to startle the animals and risk splitting the school of fish, but they make it up through physical contact.
Uses
The different types of communication are used almost always and everywhere by the dolphins. Just a few hours after birth, the dolphins can make certain whistling sounds so that they can communicate with the mother. Dolphins stay with their mother for about six years; During this time they learn to communicate, among other things. But the use of whistling tones is not without risk, because it also helps the killer whales, which belong to the genus of dolphins, to locate and hunt the dolphins. But the killer whales can not only hear the sounds, but also use them themselves to conduct a coordinated hunt.
Surname
Probably the best-known species of dolphin, the bottlenose dolphin , is the only living being, apart from humans, that recognizes itself by means of individual names. When a calf is born, the mother whistles her signature whistle almost continuously in order to impress it on the calf. Scientists at the University of St. Andrews did an experiment in which they recorded a dolphin's individual whistle signal and then removed any personal whistle peculiarities. This changed tone was then played to the next of kin. 9 out of 14 dolphins reacted to the changed signal. That means: The "names" are signature whistles that are completely independent of the "pitch" recognizable. For us this is comparable to pronouncing a name with different accents.
hunt
Communication is also a crucial factor when hunting. After the dolphins have rounded up a school of fish, they have to organize themselves so as not to lose control. (see above, body contact)
Current research
Research is currently being carried out into what the dolphins communicate with each other. The first successes have already been achieved. The researchers found that, in addition to the familiar warning and organizational signals, the animals also communicate with one another via objects. This means that they send each other the scanned objects, schools of fish and sea beds. “When a dolphin examines an object with its high-frequency sound beam, which it emits in the form of short clicks, it creates a still image - almost like a camera taking a photo. Each dolphin click is an impulse of pure sound that is modulated by the shape of the object. In other words: the reflected sound contains a semi-holographic image of the object. The dolphin picks up some of the reflected sound waves with its lower jaw, from where the sound is transmitted to the adjacent middle and inner ear , where the image is generated, ”explains researcher John Stuart Reid from England.
Dolphin and human
In experiments by John Cunningham Lilly , the bottlenose dolphin Jessi was made to make its sounds in the air and not underwater as usual. He was then rewarded whenever he made humanoid sounds and punished by lack of rewards for making dolphin sounds. After all, the dolphin was given random vowels and consonants, which the dolphin then imitated immediately, a form of mimicry that occurs in young children.
Individual evidence
- ↑ Anastasia Fugger: Dolphin language is a tough nut to crack for people. Welt.de . October 4, 2015, accessed September 14, 2016.
- ↑ Ursula Karlowski: The language of the dolphins. Sound generation. delphinschutz.org. December 2011, accessed September 14, 2016.
- ↑ Ursula Karlowski: What jumpers and speakers should have in common. delphinschutz.org. August 2009, accessed September 14, 2016.
- ↑ Dolphins recognize each other by their name. delphinschutz.org. May 2006, accessed September 14, 2016.
- ↑ Sound image language: Researchers succeed in real communication with dolphins. sein.de. December 1, 2011, accessed September 14, 2016.