few years ago, researchers had observed that some dolphins pick in Western Australia’s Shark Bay marine sponges and keep them so that they protect the sensitive snout before prickly, sharp and poisonous things in the rooting in the ground. Investigations showed that the behavior is learned: Dolphin mothers pass it on to their offspring, especially to their daughters
When rooting the reason the dolphins scare on smaller marine animals and eat them.. Ground-dwelling fish usually have no swim bladder and are therefore difficult to detect by sonar of dolphins. Scientists led by Sina Kreicker and Michael Krützen of the University of Zurich have now studied dozens of tissue samples from bottlenose dolphins of Shark Bay, one of which was unknown whether they use sponges as a tool or not.
new prey schema by tool use
Captures>was also whether the animals – like all sponge users – living in the poorer fish deep water areas of the Bay. In the long-term food was about the content of certain fatty acids in the fat layer of the animals, the so-called blubber, closed. The composition is different in bottlenose dolphins of the same deep water layer – depending on whether or not to use these sponges, the result of the analysis. With the tool use a new hunting ground has shaped itself.
The sponge users had conquered a previously inaccessible ecological niche, the researchers write. In order to compete with conspecifics will considerably reduced. This could be a reason that the Tümmlerdichte in Shark Bay is as high as in almost any other habitat of mammals. Currently there took 60 percent of those living in deeper water zones female dolphin sponges as snout saver. In the males, the proportion lies between 25 and 50 percent. For the evolution of man applies the conquest of new cultural niche as an important driver, the researchers explain further. This applies, for example for the use of milk from grazing animals as food. In eastern Shark Bay dolphins already showed that sponge users are related to each other more closely than bottlenose dolphins without the use of tools. Only a few other species was known that tools used mean a drastic, leading to the formation of different populations change of eating optionsVideo:. Siamese Twins whales discovered
Embargoed until April 23 01.01UHR snout saver changed lifestyle - Cultural Evolution in the sea: dolphins use tools
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