Toothed whales range in scott prahl thesis from the 4. Several species of odontocetes exhibit sexual dimorphism, in that there are size or other morphological differences between females and males.
They have streamlined bodies and two limbs that are modified into flippers. Toothed whales consist of some of the most widespread mammals, but some, as with the vaquita, are restricted to certain areas. Odontocetes feed largely on fish and squid, but a few, like the killer whale, feed on mammals, such as pinnipeds. Once hunted for their products, cetaceans are now protected by international law. Some species are attributed with high levels of intelligence.
In Aristotle’s time, the fourth century BC, whales were regarded as fish due to their superficial similarity. The adaptation of echolocation and enhanced fat synthesis in blubber occurred when toothed whales split apart from baleen whales, and distinguishes modern toothed whales from fully aquatic archaeocetes. Modern toothed whales do not rely on their sense of sight, but rather on their sonar to hunt prey. Echolocation also allowed toothed whales to dive deeper in search of food, with light no longer necessary for navigation, which opened up new food sources. Odontocetes, such as the sperm whale, possess teeth with cementum cells overlying dentine cells. Unlike human teeth, which are composed mostly of enamel on the portion of the tooth outside of the gum, whale teeth have cementum outside the gum.