Description

Whales have sleek, virtually hairless bodies that taper from head to tail. They range in color from black through gray to white. The whale balances itself and steers with its flippers, or forelimbs. It swims with its powerful tail, which makes up a third of its total length. The tail ends in a pair of horizontal flukes that bend as the tail moves up and down, driving the animal through the water at great speeds.

There is no outward division of the whale's body, but the skeleton is divided into head, trunk, and tail parts. The flipper bones are similar to those of the foreleg and hand (or forefoot) of land mammals, but have been modified for water living. Whales have vestigial hindlegs buried in their flesh, indicating that there was an ancestor who walked on four legs. Scientific studies indicate this animal was probably a mammal with hooves.

What Is Under All That Blubber?

Blubber is the layer of fat under a whale’s skin. Under all their blubber, whales are a lot like other mammals. Their nervous, digestive, and circulatory systems are very much like those of other mammals.

Their brain is highly complex and encased in a hard skull that is connected to a spinal cord. They have a stomach and intestines through which food is processed and a heart that pumps blood.

Whales are also wonderfully adapted to life in the sea. Because of their size, shape, and blubber, they are able to keep warm, even in the frigid polar oceans. And, they can store huge amounts of oxygen in their blood and muscles, so they are able to stay underwater for a very long time.

Baleen whales have bony skeletons, but their lightweight bones would not be strong enough to support them if they lived on land. The seawater that surrounds them helps to support their large bodies.

Whales often submerge far into the cold depths of the sea. They are protected from cold by their blubber, which is tough and acts as a cushion as well as an insulating material. Whales have small outer ears, but can hear well because water is a good conductor of sound. Whales' eyes are relatively small also, and they can see better below than above the water's surface.

Whales make a variety of sounds to communicate, and certain whales (the toothed whales) make sounds for echolocation. (Echolocation is similar in principle to sonar; the whale emits high-frequency sounds that, when reflected back to the whale, allow it to locate underwater objects.)

How Do Whales Communicate?

Baleen whales communicate with sounds and their bodies. Many baleen whales, including blue whales, make low-pitched calls that humans cannot hear. These vocalizations can travel hundreds of miles. The true function of these long-distance calls is unknown, but scientists think they allow whales to communicate even when they cannot see each other. Vocalizations are probably used in courtship and perhaps to navigate during migration.

Body language also is an important means of communicating. Whales may breach—leap out of the water—to express aggression or distress, or calves will do it out of playfulness. Another common form of body language whales use is slapping their tail on the surface—this behavior is called lobtailing. A whale may use this signal as a warning, or to let other whales know of its location in the water.

The whale's lungs and windpipe are connected only to its nasal passages, not to its mouth. Thus it can eat under water without drowning. The outer opening of the nasal passages, called the blowhole, is on top of the whale's head. Before a whale sounds (dives), it fills its lungs with air and closes its blowhole. The whale's lungs are large in proportion to its body, and are equipped with a specialized network of blood vessels that work slowly to use up all the oxygen in the lungs. Because of this well-adapted respiratory system, a whale can stay submerged for an hour or more. When the whale surfaces, it exhales warm, moist air into the colder air, making a column of steam called the spout.

What Is Spouting?

When a whale is swimming underwater, it is holding its breath. Try holding your breath for a moment. Soon you will want to resume breathing. How do you do this? You exhale. Only then can you inhale new air. Whales do the same, but they are much better at storing oxygen in their bodies than are humans. So, they can go longer periods between breaths.

When a whale exhales, it ejects a powerful blast of moist air. This is called a spout or a blow. The whale you see here is spouting.

Different species of whales have differently shaped spouts. The spout of a right whale, for example, is shaped like a giant V, while that of a gray whale looks like a single, broad cloud of mist.

Do Whales Have Belly Buttons?

Like other mammals, female baleen whales give birth to live young. Baby whales grow inside their mother’s womb and receive oxygen and vital nutrients through the umbilical cord, which is attached to their mother’s circulatory system.

The umbilical cord on a human baby is cut after a baby is born. The umbilical cord of a baleen whale breaks automatically as a calf’s head emerges from its mother’s body during the birth process. Whales are usually born fluke—or tail—first, unlike people, who most often come out head first. The place where the umbilical cord was once attached to the baby is called the navel, or belly button. So, yes, whales have belly buttons, too.