Dolphins are part of the family of toothed whales that includes orcas and pilot whales. They are mammals and breathe through a blowhole on the top of their head. Dolphin coloration varies, but they are generally gray in color with darker backs than the rest of their bodies.
Size The Amazonian River dolphin is the smallest of the dolphin species at five feet in length. It weighs about 100 lbs. The largest dolphin species is the orca. Male orcas grow to about 18 feet in length and weigh about 19,000 pounds!
Life span Most dolphin species have a long life span. It is estimated that some individuals may have lived for more than 100 years.
Variety including fish, squid and crustaceans.
It is difficult to estimate population numbers since there are many different species spanning a large geographic area.
Most species live in tropical and temperate oceans throughout the world. Five species live in rivers.
Dolphins are well known for their agility and playful behavior, making them a favorite of wildlife watchers. Many species will leap out of the water, spy-hop (rise vertically out of the water to view their surroundings) and follow ships, often synchronizing their movements with one another. Scientists believe that dolphins conserve energy by swimming alongside ships, a practice known as bow-riding.
Dolphins live in social groups of five to several hundred. They use echolocation to find prey and often hunt together by surrounding a school of fish, trapping them and taking turns swimming through the school and catching fish. Dolphins will also follow seabirds, other whales and fishing boats to feed opportunistically on the fish they scare up or discard.
Mating Season Throughout the year, though in some areas there is a peak in spring and fall.
Gestation 9-17 months depending on the species. When it is time to give birth, the female will distance herself from the pod, often going near the surface of the water.
Number of offspring Usually one calf; twins are rare.
As soon as the calf is born, the mother must quickly take it to the surface so it can take its first breath. The calf will nurse from 11 months to 2 years, and after it is done nursing it will still stay with its mother until it is between 3 and 8 years old.