Orcas
The killer whale (Orcinus orca) or orca is the largest species of dolphins. They can reach nearly 10 meters in lenght at a body weigth of more than seven tons. The most characteristic feature is the white ellipse behind the eye on the black back and the white belly. The name comes from their hunting behaviour. With the around 50 teeth (diameter is around five cm) the prey becomes fixed and easily ripped into pieces. Those can be seals, turtles, birds or rays. Depending on their prey orcas become divided into so called ecotypes. Each type is hunting for a specific prey in small groups. To do so killer whales of an specific ecotype created an invidual singing, which is compareable with the language for humans (for example hunting herrings orcas speak Norwegian, hunting seals in Argentina speak spanish and so on). Consequently they create special hunting techniques. The intelligence of those animals is impressive what can be shown -beside the ability to communicate and to hunt in adapted ways- by an example of the Californian sea: A group of killer whales and a great white shark were hunting for a seal at the same time. The great white was a predator by the point of view of the orcas and the goal was to disable him. Therefor an individual was hitting the shark into the side and flipping him on his back, while another killer whale killed him with a bite. The stunning thing is that the orcas know about the "tonic immobility" of sharks obviously. This is probably a mating reflex, which creates the situation that females are very still and a mating is possible. The orcas used it first to minimize potential dangerous. Despite or because of that advanced behaviour there are no attacks on humans in natural environments documented.
