The sea animals known as whales are among the most fascinating members of the animal kingdom. They spend all of their lives in water, yet they are not fish. Instead they are mammals—they breathe air, give birth to live young, and nurse their young like humans do. One type of whale, the blue whale, is especially remarkable. Sometimes reaching a length of more than 100 feet (30 meters) and a weight greater than 150 tons, it is the largest animal that has ever lived.

Where whales live

Whales live in oceans and seas all over the world. Some species can be found in rivers. Whales are especially plentiful in the waters surrounding Antarctica, which have a rich food supply. Most baleen whales and some toothed whales migrate at certain times of the year. This means that they travel from one place to another in search of food or to breed. Some whales cover distances of thousands of miles.

Physical features

Most whales are much smaller than the massive blue whale. The only other species that even approach the size of the blue whale are its closest relatives among the baleens. The fin whale, for example, can grow to a length of about 80 feet (24 meters). The largest toothed whale is the sperm whale. An adult male can reach a length of about 60 feet (18 meters) and weigh 53 tons. The smallest whales of all are the porpoises. The smaller porpoises are only about 4 feet (1.2 meters) long and they weigh only about 100 pounds (45 kilograms).

Whales are usually black, gray, black and white, or white. The blue whale and some other types are bluish gray. A whale's skin is smooth, but adults have a few bristles of hair in the head region. A thick layer of fat beneath the skin protects the animal from cold water. This fat is called blubber.

Whales look somewhat like large fish. Their torpedo-shaped body helps them to move quickly and gracefully through the water. A whale's tail is divided into two broad sections called flukes, which extend from side to side. Moving the tail up and down pushes a whale through the water. Two flippers attached on the front part of a whale's body are used for steering. Most whales also have a triangle-shaped fin on the back.

Like other mammals, whales are warm-blooded. This means that their body temperature stays about the same even when the outside temperature changes. Breathing air through lungs is another trait that makes mammals different than fish. Whereas fish get the oxygen they need from the water through gills, whales must go to the surface of the water to breathe. A whale takes in air through one or two openings, called blowholes, on the top of the head. Baleen whales typically have two blowholes, and toothed whales usually have one.

Behavior

Some kinds of whales travel in groups, or schools. Most toothed whales spend their whole lives in schools. These groups range in size from a few animals to more than 1,000. Baleen whales more often live alone or in small schools.

In their search for food, different types of whales dive to different depths in the ocean. The distance that a whale dives depends on how long it can stay underwater before having to come up for air. Some whales stay fairly close to the surface of the water because they have to breathe every five or seven minutes. Others can dive deeper because they can stay underwater for longer periods of time. A sperm whale, for example, can dive for an hour and a half at a time. When a whale surfaces, it blows the used air from its lungs through the blowhole. The used air looks like smoke as it rises because it is loaded with water vapor. The shape and size of the air spout can be used to tell one type of whale from another.

Whales make two different kinds of sounds underwater. Whistles, barks, screams, and other low-pitched sounds are used for communication between whales. Humans are able to hear these sounds. The other sounds made by whales are out of the range of human hearing. These sounds are used to find objects underwater through a process called echolocation. The sounds reflect off solid surfaces and then back to the whale's ears, which are quite sensitive. The whale can tell how far away an object is by how long it takes the sound to return. Echolocation is most common among toothed whales.

Whales generally stay far out at sea. Sometimes, however, they swim into very shallow water and get stranded on the beach. This is called beaching, or stranding. On land the whale is helpless, and it soon dies if it is not helped back into the water. Scientists are not sure why beaching occurs. Many believe that a failure in the echolocation process causes a whale to become confused and swim too close to shore. After a whale is stranded, it sends out a distress call. Other whales try to help, but they can become beached as well. The result is that often a number of whales are stranded together.

Life cycle

Female whales are pregnant usually for about a year before giving birth. In some species, such as sperm whales, the pregnancy can last as long as 16 months. Almost always only one offspring, or calf, is born. A whale mother typically nurses her calf for almost a year. The number of years that a whale lives varies among species. Larger whales live for about 25 to 40 years, but the smaller porpoises and dolphins do not live as long. Some scientists think it is possible for some kinds of whales to live more than 100 years.

Whale hunting

Whales have been hunted for thousands of years. Ancient peoples used whale meat to feed themselves. In more recent times people have killed whales for other reasons, especially to obtain the oil in their blubber. Whale oil was used first as lamp fuel and later in making goods such as soaps, creams, and margarine. In some years in the mid–20th century tens of thousands of whales were killed by whaling companies. The blue whale was almost wiped out altogether.

Alarm over the widespread killing of whales led to conservation efforts. In 1937 the countries with whaling operations signed the International Whaling Agreement. The agreement limited the season when whales could be hunted and the number of whaling ships a country could have. Another attempt at conservation was the creation of the International Whaling Commission (IWC) in 1946. The IWC still sets rules concerning the sizes, kinds, locations, and seasons of whale catches. In the 1980s the IWC banned all commercial whaling, meaning that companies cannot catch whales and then sell them for a profit. However, the commission allowed some native peoples to continue hunting whales for their own use. Some countries continued to hunt whales commercially despite the ban.