A dolphin leaps high out of the water and glides through a hoop. It lands back in the water with a big splash. This is the kind of trick you might see dolphins perform in shows at zoos or aquariums.
Scientists study captive dolphins in zoos and aquariums. Dolphins are noted for their intelligence, and trainers can teach them all kinds of tricks. But dolphins usually live in oceans and seas. Dolphins resemble porpoises and are related to them.
DOLPHINS ARE MAMMALS, NOT FISH
Dolphins look like fish but they are really mammals. Dolphin mothers give birth to live babies. The babies feed on milk from the mother.
Dolphins, like all other mammals, are warm-blooded. That means their bodies stay about the same temperature all the time. Fish are cold-blooded. Their bodies are the same temperature as the water around them.
HOW DO DOLPHINS BREATHE?
Like all mammals, dolphins have lungs for breathing. A dolphin breathes through a blowhole on top of its head. The dolphin takes in a deep breath, holds it, and dives. Some dolphins can dive down more than 200 feet (60 meters).
Dolphins must come up every one or two minutes for air. A dolphin blasts the air it was holding in its lungs out through the blowhole. Then it takes another deep breath and down it goes again.
THE BODIES OF DOLPHINS
Dolphins have streamlined bodies that allow them to move quickly through the water. They have two fins called flippers near the front of their bodies. Dolphins use their flippers to steer and balance in the water. Most dolphins have a long snout and a dorsal fin on their back.
The broad tail fins of a dolphin are called flukes. A dolphin waves its strong flukes up and down to swim through the water. Dolphins are among the fastest of all sea animals.
To keep warm, dolphins have a layer of fat, called blubber, beneath their skin. This layer of fat allows dolphins to maintain a constant body temperature, even in the coldest waters.
DIFFERENT KINDS OF DOLPHINS
There are at least 40 different species (kinds) of dolphins. Most dolphins are black, brown, or gray.
The biggest dolphins are killer whales (also called orcas). A killer whale can grow to 32 feet (9.8 meters) long and weigh more than 12,000 pounds (5,400 kilograms). The smallest is the tucuxi dolphin, which grows about 4 feet (1.2 meters) long and weighs about 110 pounds (50 kilograms).
Common dolphins and bottlenose dolphins are the kinds of dolphins you might see at a zoo or aquarium. Out in the ocean, spinner dolphins do flips and spins as they leap through the air.
Most dolphins live in oceans and seas all over the world. A few kinds of dolphins, called river dolphins, live in the fresh water of rivers.
WHAT DO DOLPHINS EAT?
Dolphins hunt and eat fish and squid. Killer whales eat other sea mammals, sea turtles, and birds. Dolphins use their teeth to catch prey. Some dolphins have as many as 250 cone-shaped teeth. Dolphins use their teeth for cutting, not chewing. They swallow prey whole or in large chunks.
Dolphins make clicking sounds to help them “see” in deep, dark oceans or muddy rivers. They send out clicks and wait for the sound to rebound back to them. In this way, dolphins can detect obstacles and unseen food.
Dolphins often work together when they hunt. A group of dolphins may swim in circles around a school of fish. This makes it hard for the fish to escape.
HOW SMART ARE DOLPHINS?
Scientists believe dolphins are at least as smart as dogs. Dolphins can communicate with one another. Their language is a set of whistles, screeches, and clicks.
Dolphins take care of other dolphins that need help. Dolphins will even hold a sick or injured dolphin up out of the water so that it will not drown.
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