These sounds bounce off objects and return to the middle ear, transmitted via the jaw area. A dolphin can easily discriminate between two kinds of fish with its echolocation. To maintain normal body temperature, which is similar to that of humans, dolphins have a thick layer of blubber that insulates them from the sometimes cold ocean waters. Social behavior - Some dolphin species are very social, traveling in apparently organized groups for protection, cooperative feeding, and care of the young. However, they do not have a family unit, as we know it.
Some species aggregate in enormous groups of several hundreds or thousands.
Other species are more solitary. Predators - Sharks, killer whales, and false killer whales are the primary natural predators of most dolphin and porpoise species. Atlantic bottlenose dolphins and other coastal species are at risk because of pollution, human disturbance, entanglement in gillnets, and habitat destruction. The open-ocean species are at risk of becoming entangled in the nets of several fisheries.