Dolphins are part of the family of toothed whales. The size depends on the species.

Their lifespan is very long; some have lived to be more than 100 years old. They eat fish, squid, crustaceans and more.

Their mating seasons are through the year, though in some areas there is a peak in spring and fall. They are pregnant for 9 to 17 months, depending on the species. They usually have one calf; twins are rare. The calf will nurse from 11 months to 2 years. And after it is done nursing it will stay with its mother until it is between 3 and 8 years old.

Dolphins are threatened by: marine pollution, habitat loss, harvesting, boat traffic, low frequency sonar and entanglement in fishing gear.