It is an animal that arouses the sympathy of young and old. The dolphin is known for its sociability, its intelligence, its playful side or its heroic rescues of humans in the face of sharks or the risk of drowning. In short, the dolphin is the friend we would all like to have.
But dolphins are also remarkable wild animals in many other respects. In particular, they would have the longest social memory of any mammal or the ability to not sleep for several days. As they live underwater in groups, they also have impressive communication skills.
But dolphins are also great predators of the seas, which undeniably have their dark sides. On the occasion of World Dolphin Day this Thursday, July 23, RTL invites you to discover 4 astonishing facts about these marine mammals.
1. Some dolphins know how to use tools
You thought you could outsmart the dolphins with your hammer and screwdriver? Nay, dolphins can also use tools. This is what scientists discovered in the 1980s, at Shark Bay in Australia. There, some bottlenose dolphins walk around with sponges at the end of their noses. Why ? Because the seabed is full of cutting corals and shells. With their sponges on the rostrum, the dolphins can scratch the ground without hurting themselves, and dislodge the fish that hide there.
Only a few dolphins use this technique in Shark Bay, but it is transmitted from generation to generation in the groups concerned. According to one University of New South Wales studypublished in the journal Animal Behaviour, it even appeared more than 100 years ago.
In the same place in Australia, researchers have also discovered another use of tools. Dolphins use seashells to catch fish indoors. And the technique is transmitted in the same way.
2. Dolphins have nicknames
Dolphins use sounds and whistles to communicate underwater. But to address each other, they actually have names. In 2013, researchers from the University of St. Andrews, UK, demonstrated that bottlenose dolphins in Scotland use particular whistles, or call themselves. They recognize this personal signature. “This is the first real proof of the existence of names and designations in the animal kingdom”, explained Stephanie King, one of the authors of the study.
The question that now arises is whether dolphins can associate other sounds with specific objects, and therefore have their own “words”.
3. Dolphins are rapists and murderers
You may have already heard the phrase from rapper Orelsan in Basic : “Dolphins are rapists, beware of appearances”. So no, it’s not very pleasant to read, but dolphins can be extremely violent. In Releasebiologist Richard Conor explains how some males form alliances to “kidnap” a female. “The abducted female is sequestered for several days, sometimes more than a month, and the males, unceremoniously, mate with her in turn or together”he says.
Of the infanticidal behavior have also been observed in dolphins. They kill a baby to cause the mother’s cycle to return, and thus be able to reproduce with her.
Dolphins can also be very aggressive with other species. Dolphins have been observed attacking porpoises for no apparent reason. They chase them at high speed, surround them, ram them violently and drown them. The reason for these attacks remains mysterious, as porpoises and bottlenose dolphins do not compete so much for food. Some observers evoke the hypothesis of a “sexual frustration” linked to the breeding season to explain these violent attacks.
4. Dolphins have been used as soldiers before.
In April 2019, the discovery in Norway of a beluga with a funny harness led experts to question the possibility that he was being trained by the Russian military. As surprising as it may seem, this is not the first case of a delphinid trained for military purposes. A Russian general has indeed confirmed that dolphins were “trained in the analysis of the seabed, the defense of a body of water, the attack of enemy divers or the laying of mines on the hull of enemy ships”, tells franceinfo.
Likewise, the United States developed a dolphin training program for the military in the 1960s : the US Navy Marine Mammal Program. They served during the Vietnam War, in particular to search for objects under water and to monitor the bottoms. According to Guardianthey were even used during the Gulf War and the invasion of Iraq to search for mines.