A dolphin is an aquatic mammal in the clade Odontoceti (toothed whale). Dolphins range in size from the 1.7-metre-long and 50-kilogram Maui's dolphin to the 9.5 m and 10-tonne orca. Dolphins are widespread. Most species prefer the warm waters of the tropic zones, but some, such as the right whale dolphin, prefer colder climates. Dolphins feed largely on fish and squid, but a few, such as the orca, feed on large mammals such as seals.