Baleen, or Whalebone, Whales

Gray whales are found in the North Pacific. They grow to about 50 feet (15 m) in length and are grayish with white mottling. Their bodies are typically encrusted with barnacles and whale lice. Gray whales migrate from the Bering and Chukchi Seas in the Arctic to southern California. It is the longest migration of any mammal, with a round-trip distance of 10,000 miles (16,000 km). In migrating, schools of gray whales come so close to shore that watching them is a major tourist attraction in California. In the early 1900's gray whales were on the verge of extinction, but the population is now stable.

Gray whales migrate between the Bering Sea off Alaska and the shallow bays of Baja California, Mexico. During their migration, they swim along the coasts of Alaska, Washington, Oregon, and California.

Their migration is one of the longest in the animal kingdom. Some gray whales swim 5,000 miles (8,000 kilometers) one way. The females are especially impressive because they make one migration journey while pregnant and another soon after giving birth.

Because they feed on bottom animals, gray whales stay closer to shore than other whales. For this reason, whale watchers on the West Coast often see more gray whales than other species, such as blue whales.

Gray whales used to live off the East Coast of the United States. That population is now extinct. Today, a small population still lives off the coast of Asia, and these whales migrate between the coasts of Russia and southern China.

Rorquals have dorsal fins and long grooves running lengthwise in the skin of the throat. Among these whales—most of which have been hunted to near extinction—are the following:

the largest animal that has ever lived. Blue whales grow to more than 100 feet (30 m) in length and reach a weight of about 140 tons (127,000 kg). The blue whale is mainly bluegray with light spots. The name sulfurbottom comes from the fact that the underside of the whale commonly becomes coated with yellowish microscopic algae. Blue whales swim at a top speed of about 30 mph (48 km/h).

A blue whale’s heart is the size of a small car. Its tongue weighs as much as an elephant. A toddler could easily fit into one of its blowholes. A single blue whale is heavier than a group of 1,600 average-sized people.

Blue whales are not just big, they are absolutely, incredibly, and astoundingly huge—bigger than any dinosaur that ever lived. A blue whale can reach 100 feet (30 meters) in length and may tip the scales at 300,000 pounds (136,000 kilograms).

As with all baleen whales, female blue whales are larger than males.

Krill for breakfast. Krill for lunch. Krill for dinner. Blue whales that spend the summer months in cold polar waters eat a whole lot of one thing—krill.

Krill resemble shrimp. They have long antennae, dark eyes, and delicate, almost transparent (see-through), bodies. Some kinds of krill are much smaller than the shrimp people eat. These krill, which are the type blue whales eat, have bodies about half as long as a penny is across.

Krill make good whale food because of their abundance and high nutritional value. Pound for pound, krill contain as much protein as red meat, and they contain all the energy, trace minerals, and vitamins that blue whales require.

It does, however, take a lot of krill to fill a hungry whale. During the summer feeding season, a blue whale may devour over 10,000 pounds (4,536 kilograms) of krill a day.

When blue whales feed, they take huge gulps of water. For this reason, they are called gulpers.

Like all rorqual whales, blue whales have pleats on their throat that expand just like an accordion. By gulping, they transform their throat into a giant pouch. By pressing their tongue against their baleen, the whales squeeze out the water. Then they eat the krill that remain trapped against the baleen.

Humpback, sei, minke, and fin whales are also “gulpers.” Right whales and bowhead whales, however, are “skimmers.” They swim slowly near the sea surface, continuously straining seawater through their baleen.

The gray whale is different from all the other baleen whales in its feeding habits. Gray whales eat the tiny animals from the mud and sand on the floor of the ocean. To do this, the whales plow the bottom of the sea with their heads and suck up huge scoops of muck.

Blue whales inhabit some of the coldest waters and some of the warmest waters on the planet. Yet, they maintain a constant body temperature of about 98 degrees Fahrenheit (36.6 degrees Celsius), nearly the same as our body temperature of 98.6 degrees Fahrenheit (37 degrees Celsius).

Amazingly, blue whales are so well adapted for cold temperatures that it is easy for them to keep warm in cold waters. The shape and large size of a blue whale’s body help it to retain heat. Normally, a blue whale has very little blood in its body’s outer layers, and this also helps the whale to keep body heat inside.

Blue whales actually have a harder time getting rid of excess heat. So, unlike other whales, they don’t need as thick a layer of blubber. A blue whale’s blubber is only 6 inches (15 centimeters) thick, whereas some other whales are covered in a 20-inch (51-centimeter) layer. A blue whale may get rid of excess heat by sending more blood than normal to its skin surface, which cools the whale’s blood.

Blue whales and other baleen whales have good eyesight. Unlike the round eyes of humans, however, baleen whales have eyes that are flattened in the front. This eye shape is better for seeing in a dim, underwater habitat.

Baleen whales also have amazing hearing. They hear sounds that are inaudible to humans. A whale’s ear doesn’t look like it would be so sensitive to sound. Its ear looks like a tiny hole in the side of its head. There is no ear lobe or outer ear.

Touch is another sense that is very well developed in these whales. A baleen whale’s skin is very sensitive to touch.

Though whales can see, hear, and feel, scientists are not certain if they have any sense of smell.

An animal as large as a blue whale has few natural enemies. Only diseased or young blue whales are at risk of being attacked by sharks or killer whales.

Newborn whales are the most vulnerable because they are small and swim slowly. Mother whales swim beside their young, shielding them from predators.

If a group of killer whales targets a young whale, however, it is a challenge to protect it. Lacking teeth, claws, or tusks, blue whales have only their size—and powerful tail—to ward off attack. Killer whales will rip small chunks of flesh from a young or sick whale until it finally dies.

It is humans, however, and not killer whales, that have been the most dangerous enemy of blue whales. Hunting and water pollution have killed many whales.

For the first year or so, a calf stays with its mother. After that, it is independent. Though blue whales don’t have a long childhood, blue whale mothers are very attentive while they care for their young. A mother never leaves her young calf until the calf is ready to set out on its own.

Eating is an important part of a young blue whale’s life. A newborn calf weighs about 6,000 pounds (2,700 kilograms). Nursing on its mother’s fatty milk, it gains about 200 pounds (90 kilograms) a day. By the time it is 7 months old, it will be about 50 feet (15 meters) long and will weigh about 46,000 pounds (21,000 kilograms)—it is then ready to begin feeding on krill.

Nursing a young whale is extremely taxing on a mother whale. A mother whale may lose as much as 100,000 pounds (45,400 kilograms), possibly as much as one-third of her body weight, while nursing.

After a blue whale calf separates from its mother, a blue whale will spend most of its time alone. Blue whales are rarely seen in the large groups that are common to dolphins, killer whales, and other toothed whales.

Biologists sometimes see pairs of blue whales swimming and feeding together. These pairs will usually consist of a female and a male, or a female and its calf.

Like the blue whale, most other baleen whales spend much of their time alone. However, humpback, right, and gray whales are known to form small groups. These groups may contain a dozen or so whales feeding and traveling together.

You may be surprised to learn that a blue whale’s closest living relatives on land include pigs, deer, and hippopotamuses. The first whales, which appeared more than 50 million years ago, had evolved from primitive hoofed mammals.

The early ancestors of whales had teeth, lived on land, and had four legs that ended in hoofs. They foraged for food in shallow coastal waters. Slowly, over millions of years, the body shape of these animals changed. Front legs developed into flippers. Back legs disappeared. The nostrils moved to the back of the snout, becoming blowholes.

Amazingly, even modern whales show traces of their origins as walking land mammals. Baleen whales have tiny hipbones, which are all that remain of their back legs. And, a baleen whale fetus has teeth while it develops inside its mother. These teeth disappear before birth.