Porpoises

Porpoises are abundant and found in a multitude of environments, including rivers (finless porpoise), coastal and shelf waters (harbour porpoise, vaquita) and open ocean (Dall's porpoise and spectacled porpoise), covering all water temperatures from tropical (Sea of Cortez, vaquita) to polar (Greenland, harbour porpoise). Porpoises feed largely on fish and squid, much like the rest of the odontocetes. Little is known about reproductive behaviour. Females may have one calf every year under favourable conditions. Calves are typically born in the spring and summer months and remain dependent on the female until the following spring. Porpoises produce ultrasonic clicks, which are used for both navigation (echolocation) and social communication. In contrast to many dolphin species, porpoises do not form large social groups.