The most common and well-known dolphin is the bottlenose dolphin. It is around 8 feet (2.5m) long and weighs between 440-660 lbs (200-300kg). Dolphins are so diverse that they range in size. The smallest dolphin is the Maui's Dolphin and is around 4 feet (1.2m) long and weighs around 90 lbs (40 kg). The largest dolphin is the orca, or killer whale, and the males can grow to about 25 feet in length and weigh about 19,000 pounds.
Dolphins are considered to be highly intelligent marine mammals. They are carnivores, mostly eating fish and squid. Dolphins swallow their prey whole and do not chew their food. To prevent drowning while sleeping only half of the dolphin's brain goes to sleep while the other half remains awake so they can continue to breathe. They breathe though a hole on top of their head called a blowhole.
Most dolphins live only 25 to 30 years in the wild. However, some dolphins, in captivity have lived to be 40 years old. Dolphins communicate with each other through clicking, whistling, and other noises. When a new baby dolphin is born, called a calf, along with its mother's help it immediately heads for the surface of the water for its first breath. It is nursed on the surface as the mother turns on her side to allow the calf to breathe easily while nursing.