Whale is a large ocean mammal. A whale may resemble a fish in basic body shape, but the two animals differ greatly. For example, fish breathe by means of gills, which absorb oxygen dissolved in the water. A whale, on the other hand, gets oxygen through its lungs and must come to the surface to breathe. Like other mammals, whales give birth to live young, and the calf (baby whale) feeds on its mother’s milk. Most fish lay eggs, by contrast, and fish do not make milk for their offspring. Whales are also warm-blooded—that is, a whale’s body temperature remains about the same regardless of the temperature of its surroundings. Nearly all fish are cold-blooded. A fish’s body temperature changes with the temperature of the water. An obvious difference between the body of a whale and that of fish is in the tail. Fish have tail fins oriented vertically (up and down). Whales have horizontal (side to side) tail fins.
Loading the player...Whale
Most whales are enormous. One kind, the blue whale, may be the largest animal that has ever lived. Blue whales can grow up to 100 feet (30 meters) long. They may weigh over 150 tons (135 metric tons). But some kinds of whales are much smaller. For example, beluga whales usually reach only 13 to 16 feet (4 to 5 meters) long and weigh about 1 ton (0.9 metric ton).
Loading the player...Humpback whale mother and calf
Whales rank among the most intelligent animals. They have large brains and show evidence of advance thought-processing capabilities similar to those seen in chimpanzees and elephants. Some whales also engage in complex social behavior. For example, female sperm whales live in groups made up of close relatives and their calves. Evidence suggests that older females lead the group, teaching feeding locations and migration routes to younger whales. The older females also help defend the calves against threats.
Whales differ from most other mammals in several ways. For example, most mammals have bodies covered in hair. But whales have only a few stiff hairs on the head. Most mammals have four legs. A whale has no hind legs, and its front legs are flippers. Whales also can hold their breath for much longer than can most other mammals. The sperm whale can hold its breath for up to about 2 hours.
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Killer whale
Whales belong to a group of mammals called cetaceans << sih TAY shuhnz >> . This name comes from a Latin word meaning large sea animal. Scientists have identified nearly 90 species (kinds) of cetaceans. Dolphins and porpoises are also cetaceans. However, people usually do not think of dolphins and porpoises as whales, in part because most of these animals are relatively small. Some animals that are called whales are actually dolphins. For example, pilot whales are large dolphins, as are killer whales.
Scientists divide the various kinds of whales into two major groups: baleen whales and toothed whales. Baleen whales do not have teeth as adults. Toothed whales do.
Instead of teeth, an adult baleen whale has hundreds of thin plates in the mouth. The whale uses these plates to strain food from the water. The plates are called baleen or whalebone. They are made up of keratin, the same material that makes up human hair and fingernails. The baleen hangs from the whale’s upper jaw. The inside edges of the plates have brushlike fibers that filter out the food. Large baleen whales feed mainly on plankton, the mass of tiny organisms (living things) that drift with the ocean currents. Smaller baleen whales also feed on plankton, but some eat small fish as well.
People have hunted whales since prehistoric times. Whales have been killed for their meat and for whale oil, which is obtained from a whale’s fat. In the past, people widely used whale oil as a fuel for lamps and for cooking. Parts of whales have also been used to make a variety of products, including cosmetics, fertilizer, glue, medicines, and soap. Today, some people in Japan still eat whale meat. So do some native peoples of the Arctic.
During the early to mid-1900’s, whalers (whale hunters) killed huge numbers of whales. Whaling nearly caused the extinction of several species. In 1946, the major whaling countries formed the International Whaling Commission to regulate the whaling industry. The commission voted to suspend commercial whaling in 1982, and the laws of many countries now ban whaling and the import of whale products. Most whale species have recovered to some extent, but whale numbers remain far below previous levels.
The body of a whale
A whale has the same basic body features as other mammals. But whales have many special characteristics suited to life in the water. Living in water also enables whales to reach enormous sizes. A land animal can grow only so big before its bones and muscles can no longer support its body weight. But the buoyancy (lift) of water helps support a whale’s body. The support of water makes it possible for some whales to grow larger than any land animal, including the largest dinosaurs.
Body shape.
A whale, like a fish, has a body shape that is streamlined, enabling it to swim with minimal resistance. A whale propels itself by moving its powerful tail fins, called flukes, up and down. Most fish, by contrast, swim by swinging their tail fins from side to side. A whale also has two flippers near the front of the body. The flippers help in steering and maintaining balance.
Skeleton.
A whale’s backbone, ribcage, and shoulder blades resemble those of other mammals. Such whales as humpbacks have additional finger bones in the flipper, helping the whale to swim more efficiently. Whales lack external hind limbs. Two small bones buried in the hip muscles are all that remain of the hind limbs of whales’ land-dwelling ancestors.
Nearly all mammals have necks consisting of seven bones called vertebrae. In some whales, the neck vertebrae are compressed in length or fused (joined together). These features help keep the head from moving about as a whale swims. They also contribute to the whale’s streamlined shape, joining the head to the body without a distinct neck. Rorquals << RAWR kwuhls >> and some other whales do have separated neck vertebrae. This feature makes the neck more flexible, likely helping the whale to feed in narrow places.
Skin and blubber.
A whale has smooth, rubbery skin that slips easily through the water. Stiff bristles on the head are a whale’s only hair.
Most mammals are insulated by their hair, which holds warm air next to the body. Whales instead have blubber, a layer of fat beneath the skin. Blubber keeps a whale warm even in cold waters. In fact, whales have more difficulty getting rid of excess heat than keeping warm. The blubber of many whales grows no more than about 6 inches (15 centimeters) thick. In contrast, right whales may have a layer of blubber up to 20 inches (50 centimeters) thick.
Blubber stores energy as fat, and a whale can live of its blubber for a long time. For example, large baleen whales feed little for about eight months while migrating and breeding. In addition, blubber is lighter than water, increasing a whale’s buoyancy.
Respiratory system.
Whales have lungs and must come to the surface to breathe, usually every 5 to 15 minutes. But many whales can go as long as 40 minutes without breathing. A sperm whale can hold its breath up to about 2 hours.
Several adaptations enable a whale to go without breathing for long periods. A whale’s muscles store much more oxygen than do those of other mammals. For example, human beings store only about 13 percent of their oxygen supply in the muscles, compared with about 41 percent among whales. During a dive, a whale’s body reduces blood flow to the muscles but keeps a normal flow to the heart and brain. The heartbeat also slows, helping to save oxygen. After a dive, a whale must take several breaths to recharge its tissues with oxygen.
When a whale comes up to breathe, it rolls forward as it breaks the surface. This movement gives the whale only about two seconds to exhale and to breathe in up to 70 cubic feet (2 cubic meters) of air. Whales breathe through nostrils called blowholes at the top of the head. A toothed whale has one blowhole. A baleen whale has two. Powerful muscles and valves open the blowholes wide for whales to breathe. The openings snap tightly shut when the whale is underwater.
Senses.
Most kinds of whales have good eyesight. Whales also have well-developed senses of taste and touch. Whales have essentially no sense of smell, though baleen whales have a more developed scent organ than do toothed whales.
Hearing is the most important sense for many whales. Their keen hearing provides them with much information about their surroundings. Whales can hear a wide range of sounds. The range of their hearing includes low- and high-pitched sounds far beyond the range of human hearing. Whales can also tell from what direction a sound is coming underwater.
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Sperm whale
Toothed whales produce sounds within the nasal sac system, a series of air-filled pouches below the blowhole. The whale generates high-pitched sounds by forcing air between these structures. The melon, a fatty structure on top of the head, focuses the sounds. The whales locate objects underwater by listening for the echoes produced when the sounds bounce off them. Returning echoes pass through and under bodies of fat in and below the whale’s lower jaw before being transmitted to the ear. From the echoes, a whale can determine the distance and direction to an object. This method of sensing the whale’s surroundings is called echolocation. Biologists believe that baleen whales cannot echolocate.
The life of a whale
Reproduction.
Most kinds of whales mate during a specific season. The male and the female engage in courting as part of the mating process. The male is called a bull. The female is called a cow. During courtship, the whales may stroke each other with their flippers. Bulls may jostle aggressively as they compete for cows. One bull may mate with several cows during a breeding season. Similarly, a cow may mate with several bulls.
The pregnancy period varies from species to species. In most species, it lasts 10 to 12 months. However, a sperm whale’s pregnancy lasts for 15 months. In almost all cases, a whale has only one offspring, or calf, at a time. Twins occur only rarely. One or more other females may assist the mother during birth.
Whales are already giant animals at birth. A newborn blue whale weighs about 2 tons (1.8 metric tons) and measures about 23 feet (7 meters) in length. As soon as the calf is born, the mother nudges it to the surface to take its first breath.
A mother whale is protective of her calf and stays close to it for at least a year. Young blue whales and fin whales nurse up to seven months. Most other whales nurse for about a year. Sperm whales and pilot whales may nurse their young, at least occasionally, for three years or more. A mother whale has special breast muscles that pump milk into the calf’s mouth. Whale milk is concentrated. It is far richer in fat, protein, and minerals than the milk of land mammals. This rich food helps whale calves to grow quickly. For example, baby blue whales gain about 200 pounds (90 kilograms) per day.
Group life.
Whales live in groups called family units, pods, or schools. Toothed whales appear to be more socially organized than baleen whales, and many toothed whales show cooperation among individuals. Toothed whales often live together for many years, especially female offspring of the same mother. Sperm whales, for example, form both all-male groups and distinct family units, which consist of several closely related females and their calves.
Most baleen whales live alone or in small groups. The young usually stay with their mothers for a year or less. However, baleen whales sometimes gather in large groups at their feeding or breeding grounds.
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Killer whale
Whales communicate with one another by making a variety of sounds called phonations. Toothed whales can produce sounds that are too high-pitched for humans to hear. Large baleen whales can produce sounds that are too low-pitched for people to hear. Whales can easily hear these sounds over great distances. Microphones have picked up the deep moans of blue whales at a distance of over 50 miles (80 kilometers). Scientists believe that whales use phonations to maintain contact with one another and to coordinate group activities.
The best-known whale sounds are the songs of the humpback whale. Each song consists of a series of sounds lasting up to 20 minutes that may be repeated. All male humpback whales living in the same area produce basically the same song. But the songs of humpbacks in different areas vary. The songs also change gradually from year to year. Humpbacks produce their songs in the areas where they meet during breeding season. Scientists think that male humpbacks may use the songs to maintain distance from other males.
Migration.
Most kinds of baleen whales migrate between polar and tropical regions. The cold waters of the Arctic and Antarctic are rich with plankton in the summer. The whales visit these areas to feed, building up blubber. As winter approaches, polar waters freeze over. The whales move to warmer seas. There they mate. The females that are already pregnant give birth. The warm waters may provide a comfortable environment for the calves. In the tropics, adult whales live mostly off their blubber, because food is scarce. Mother whales use energy and nutrients stored in blubber to make milk for their calves. By late spring, whales return to polar areas to feed.
Two kinds of baleen whales do not migrate. Some Bryde’s << BROO duhs >> whales live in the tropics the year around. Bowhead whales never leave the Arctic. Most species of toothed whales also do not migrate. Belugas and narwhals stay in Arctic waters. Most sperm whales live only in tropical or temperate (mild) seas. But older, larger males spend the summer in polar waters.
Life span.
The life span of a whale ranges from around 12 years for a harbor porpoise to more than 200 years for a bowhead whale. Human activities and large predators cause many whale deaths. Killer whales and large sharks occasionally attack young, weak, or diseased whales. Whales that avoid death by human activity and large predators may die of disease or old age.
Scientists do not know for certain what causes strandings. They have proposed a number of explanations. Some suggest that illness, old age, or parasites in the ears or brain may interfere with whales’ ability to echolocate. Other scientists suggest that gently sloping beaches reflect sounds over the heads of the whales. As a result, the whales do not sense that they are swimming onto a beach. Some scientists think whales navigate by sensing Earth’s natural magnetic field, as do some birds. These scientists suggest that magnetic activity may confuse or misguide the animals, causing them to strand. Noise made by human beings may also play a role in strandings. Such noise may result from commercial ship traffic, oil exploration, and powerful sonar technology. Such noise pollution has been shown to cause changes in the behavior of whales. In some cases, noise pollution has caused injury or even death. Many scientists suspect that stranding of whales may have a variety of causes.
Whales and the environment
Whales are a vital part of many ecosystems. An ecosystem consists of all the living and nonliving things in an area and the relationships among them. Whales eat such vast amounts of food that they help to shape food webs. A food web consists of the feeding relationships among a diversity of living things. Whales also help to transfer nutrients (nourishing substances) between different layers of the ocean.
Effect on food webs.
Whales play a key role in regulating the abundance and distribution of prey in the oceans. Baleen whales in particular consume enormous amounts of plankton. When food is plentiful, an individual blue whale can eat about 40 million shrimplike krill a day, comprising about 4 tons (3.6 metric tons). The krill feed mainly on plantlike phytoplankton, which make their own food using the energy in sunlight. Ultimately, such plankton provides nearly all of the food energy in ocean ecosystems. Some ocean animals depend on this plankton directly, by feeding on it. But many other animals depend on plankton indirectly, by feeding on animals that eat it. Thus, the feeding of whales on plankton affects many other animals in ocean ecosystems.
The removal of most large baleen and sperm whales through whaling has caused many changes to food webs. For instance, the loss of large baleen whales from the ocean surrounding Antarctica caused an increase in the number of krill. Minke whales and certain penguins also feed on krill. These animals have become more abundant because they no longer must compete with large whales for krill.
The whale pump.
Whales also transfer nutrients between different layers of the ocean. Many whales dive to feed on prey, in some cases to depths greater than 3,000 feet (900 meters) below the surface. These whales later release their waste at the surface, enriching waters there with such nutrients as iron and nitrogen. This transfer of nutrients from the deep ocean to the surface is sometimes called the whale pump. Nutrients brought up in the whale pump support the growth of plankton, providing food for many fish and other animals.
Whale fall.
Even the bones of the fallen whale are consumed eventually. Unusual animals called zombie worms grow on the dead skeleton, extending special rootlike structures into the bones. Bacteria that live inside the worm help it to break down the bone and release stored nutrients. Ultimately, sulfur-seeking bacteria break down the whale bones completely, leaving only a faint trace where the whale remains once rested.
Whales and people
Whaling
began in prehistoric times. At first, people simply killed and ate whales that had become stranded on beaches. People who lived in what is now Norway were probably among the earliest to seek out and kill whales at sea. Norwegian rock carvings that are about 4,000 years old show a variety of whaling scenes.
The Basque people of southwestern France and northern Spain established the first large-scale whaling industry in Europe in the 900’s. The Basques hunted near the shore from small open boats. During the 1200’s, the Basques began to equip large sailing ships for whaling voyages. Each ship carried several small whaleboats from which the whalers set out to kill whales. The whalers stored blubber and baleen on the ship until they had a full load. The ship then returned to shore. On shore, the blubber was cooked to make oil. This oil was burned in lamps to provide light. The baleen was used in such articles as corsets, dress hoops, and whips.
Many European nations began whaling during the 1600’s. Dutch and English whalers began to hunt and kill large numbers of whales in the Arctic. Around the same time, American colonists began to hunt whales off the Atlantic coast. By 1800, whalers from the United States were hunting sperm whales throughout the Atlantic Ocean and in the South Pacific Ocean. However, whaling in the United States went into serious decline during the American Civil War (1861-1865) and never recovered.
In the 1900’s, whalers developed the factory ship. A factory ship was a huge vessel that was served by a fleet of catcher boats used to capture whales. The factory ship was equipped to process a wide variety of whale products. A modern factory-ship fleet included diesel-powered catcher boats and a crew of about 400. Spotters in airplanes or helicopters helped the whalers search for whales. In addition, the ships had sonar to track whales underwater. These advanced techniques enabled the crew of a catcher boat to track down and kill nearly every whale they encountered.
Modern whaling techniques proved highly effective. As a result, more whales were killed during the first 40 years of the 1900’s than over the preceding 400 years. The number of whales killed worldwide peaked in 1962, when 66,000 were killed. Many kinds of whales became rare, and some species nearly went extinct.
Conservation.
The populations of many kinds of whales collapsed in the 1900’s because of excessive whaling. Whalers killed so many blue, bowhead, humpback, and right whales that these species nearly became extinct. For example, scientists estimate that about 350,000 blue whales once lived in Antarctic waters. Only about 2,000 blue whales survive in these waters today. Whaling also greatly reduced the number of fin, gray, northern right, and sei (pronounced say) whales.
In 1946, the major whaling countries formed the International Whaling Commission (IWC) to regulate the whaling industry. For many years, the IWC established high quotas (limits) on the number of whales that could be killed. During the 1960’s and 1970’s, it began to reduce quotas, as evidence grew that many whales were becoming endangered. It also banned the hunting of several whale species and limited use of factory ships.
Public opinion in the United States, Canada, and some European countries has long opposed commercial whaling. In 1971, the U.S. government ordered an end to commercial whaling. It also outlawed the import of whale products. In 1973, antiwhaling groups agreed to boycott (refuse to buy) products from Japan and the Soviet Union until those countries stopped commercial whaling.
In 1982, the IWC approved a moratorium (temporary ban) on commercial whaling. The moratorium began with the 1985 and the 1986 hunting seasons. By 1988, all nations had halted commercial whaling. Since that time, a few nations have resumed limited commercial whaling.
The IWC permits native peoples who have traditionally hunted whales to continue limited hunting. These peoples include the Inuit of Alaska, Canada, Greenland, and Russia. These people have traditionally eaten whale blubber, meat, and skin. The commission regulates which whales they may hunt and the hunting methods used. The IWC also permits the killing of whales for scientific research. This practice has created considerable controversy. For example, Japanese ships killed hundreds of whales each year for research purposes. Critics argued that this research is only a pretense for continued commercial whaling. In 2018, Japan left the IWC and announced that it would resume commercial whaling. It did so in 2019. Japan joins Iceland and Norway as the only countries that ignore the IWC moratorium on commercial whaling. 
Many whale species have recovered to some degree following the ban on commercial whaling. For example, scientists estimate that whalers killed more than 200,000 humpback whales in the Southern Hemisphere alone, nearly causing their extinction. Since the ban, humpback whales in the Southern Hemisphere have gradually recovered to about 36,000 whales. But this population remains far smaller than the original.
Some whales species have not been able to recover. For example, right whales have been fully protected since 1935, but their numbers have not yet rebounded. Most scientists believe that large whales will need protection for many more years to ensure their survival.
The accidental capture of whales through fishing activities remains a serious threat to whales. Species that are caught accidentally are known as bycatch. Whales can also become entangled and drown in the nets, lines, and traps of commercial fishing gear. The number of entanglements has been reduced through the use of acoustic alarms or pingers that warn away whales. But scientists have discovered that these alarms can attract other whales, which learn to follow them to find food.
The evolution of whales
Scientific evidence shows that whales descended from land mammals that lived about 50 million years ago. Whales evolved (changed over many generations) from these even-toed, hoofed mammals. The closest living relatives of whales are hippopotamuses.
Whales arose among close relatives of the raoellids << rah oh EHL ihdz >> . The raoellids were a group of cat-sized, hoofed mammals. A raoellid had a long nose and tail, with long, slender legs. Raoellids spent much of their time in the water. They may have fed mainly on water plants, though they may also have come onto land to eat plants, as do modern hippopotamuses. Fossils of raoellids are known only from India and Pakistan.
The earliest whale ancestors belong to three major groups, called pakicetids, ambulocetids, and remingtonocetids. Pakicetids somewhat resembled wolves. A pakicetid had a long nose and tail, with crushing teeth adapted for eating fish. The ambulocetids were otterlike in shape and size. An ambulocetid swam using its hind limbs and tail. A remingtonocetid had a long snout and somewhat resembled a crocodile. The teeth of remingtonocetids lacked the crushing parts of pakicetids and ambulocetids, suggesting that their diet was different from that of other whale ancestors.
Early whales lived in the shallow waters of the seaway between India and Pakistan. These whales still had legs and could wade in freshwater streams. Whales later spread to ocean waters near shore and then to fully oceanic habitats. Over time, some whales became better adapted to an aquatic way of life. This transition involved significant changes in both feeding and movement.
A group of whales known as the basilosaurids first appeared about 40 million years ago. A basilosaurid had smaller hind limbs than other early whales, and its hips were not attached to the backbone. As a result, the hind limbs were unable to support the whale’s body weight, and the animal could not walk. Basilosaurids swam using their tails, as do modern whales.
Modern whales arose from ancient whales about 34 million years ago. They appeared at a time when the oceans were changing rapidly, with increased availability of food providing new opportunities. Fossils of the earliest toothed whales come from North America. They belong to three or four groups, and most had many different-sized teeth. Later toothed whales such as beaked whales evolved to have fewer teeth, and the teeth were more uniform in size. Early toothed whales are thought to have captured food using echolocation, as do modern toothed whales.
The earliest baleen whales are known from fossils from New Zealand and Antarctica. They had large teeth with many cusps (surface bumps), and some of them probably had both teeth and baleen. Baleen whales gradually lost their teeth. They evolved large mouths and flexible jaws. Some baleen whales developed large grooves and pouches in the throat. These adaptations enabled the whales to take in enormous gulps of water and prey. 
Most of the surviving whale groups arose about 12 million years ago, as many new kinds of baleen and toothed whales appeared. Whale diversity reached its peak at this time. Over the last 3 million to 4 million years, whale diversity has declined as the diversity of food available to whales has decreased.
Kinds of whales
Loading the player...Bowhead whale
Baleen whales
are classified into five groups. These groups are (1) right whales, (2) bowhead whales; (3) pygmy right whales; (4) gray whales; and (5) rorquals.
Right whales
have a thick, solid body and a huge head. The head of most right whales makes up about a third of the total body length. Right whales swim slowly. They feed by swimming into a mass of plankton with their mouths open. Water flows through the baleen, and plankton becomes entangled in the baleen fibers.
Bowhead whales
are closely related to right whales. Bowhead whales have the longest baleen of all whales, reaching up to 13 feet (4 meters) long. A bowhead whale has a highly arched mouth to accommodate this huge baleen. The whale is black with white areas on the chin. Some bowheads also have whitish patches on the belly and around the flippers and tail. Bowhead whales measure up to 65 feet (20 meters) long. They live only in the Arctic Ocean. Bowhead whales may also be called Greenland right whales.
Pygmy right whales
resemble right whales but are smaller. They grow no longer than 20 feet (6 meters). Unlike a right whale, a pygmy right whale has a dorsal (back) fin. Pygmy right whales live south of the equator.
Gray whales
live in the North Pacific Ocean. A gray whale’s skin is gray, with white blotches. The animal has a series of low humps on the lower back. A gray whale may measure up to 43 feet (13 meters) long. Gray whales eat animals that live on the sandy ocean bottom. The whales suck up sand and mud, using their coarse, short baleen to strain out the bottom-dwelling animals.
Loading the player...Gray whale
Rorquals
are baleen whales named with the Norwegian word for furrow whale. The name refers to long grooves on the whale’s throat and chest. The grooves enable a rorqual to open its mouth wide and gulp enormous quantities of water and prey. Rorquals lunge quickly forward into their prey. As the whale closes its mouth, its tongue forces water out through the baleen. The prey is trapped inside.
All rorquals have a dorsal fin. Because of the fin, they are sometimes called finback whales. Most rorquals have a long, streamlined shape. Rorquals can swim faster than other types of whales.
There are seven kinds of rorquals. They are (1) blue whales; (2) Bryde’s whales; (3) fin whales; (4) humpback whales; (5) minke whales; (6) Omura’s whales; and (7) sei whales.
Blue whales are the largest animals that have ever lived. They may grow up to 100 feet (30 meters) long. They can weigh more than 150 tons (135 metric tons). They are speckled blue-gray and white but appear evenly blue underwater. Blue whales live in all the oceans. They feed almost entirely on krill.
Bryde’s whales live only in tropical and subtropical seas. They are dark gray. The whales reach about 45 feet (14 meters) in length. Unlike other rorquals, Bryde’s whales eat mainly small fish and squid.
Fin whales are dark gray on top and whitish below. Fin whales grow up to 88 feet (27 meters) long. They live in all the oceans. Fin whales eat krill, shellfish, and small fish.
Humpback whales grow up to 62 feet (19 meters) in length. The humpback whale’s most outstanding feature is its long flippers. The flippers may be a third as long as the body. The body is black on top and white underneath. Wartlike knobs cover the head. Humpback whales live in all the oceans. They often swim in coastal waters. They feed on krill and small fish.
Minke whales are the smallest of the rorquals. They measure no more than 33 feet (10 meters) long. They are black or dark gray on top and lighter below. Minke whales live in all the seas. Those in the Southern Hemisphere feed mainly on krill. Those in the Northern Hemisphere also eat small fish.
Omura’s whales are small-sized rorquals found in tropical and subtropical waters around Indonesia, Japan, and the Philippines. They rank among the smallest rorquals, ranging from 33 to 39 feet (10 to 12 meters) long. The whale resembles the larger fin whale, with white on the right lower jaw and black on the left side. It also has streaks radiating out from the eyes. The whale is usually yellowish-white to black overall, sometimes with two different shades on the same animal. Scientists are not certain what Omura’s whales eat because the whales are rarely sighted. They likely feed on fish.
Sei whales look much like smaller fin whales. They may grow up to 62 feet (19 meters) long. Sei whales live in all the oceans. They feed on fish, squid, and shellfish.
Toothed whales.
Scientists divide the various kinds of toothed whales into three groups. These groups are (1) sperm whales; (2) beaked whales; and (3) belugas and narwhals. In addition, dolphins and porpoises are toothed whales.
Sperm whales
are by far the largest toothed whales. Males grow about one-third larger than females, reaching about 60 feet (18 meters) long. Sperm whales range in color from brownish-black to dark gray. The sperm whale has a huge, square-shaped head that makes up about a third of its total body length. The lower jaw is long and thin. It has 18 to 25 peglike teeth on each side. The teeth fit into sockets in the toothless upper jaw.
Most sperm whales live only in tropical and temperate waters. Mature males, however, spend the summer in polar seas. They dive to great depths for food, which consists mainly of large squid. They also eat certain fishes, such as cod, skate, barracuda, and shark. The sperm whale has two smaller relatives, the pygmy and the dwarf sperm whales.
Beaked whales
have a beaklike snout. The beaked whale has only two or four teeth in the lower jaw. Most have no upper teeth. Some kinds of beaked whales grow only about 12 feet (3.7 meters) long. Others reach 42 feet (13 meters) in length. Beaked whales live in all the oceans. They feed mainly on squid and fish. There are nearly 20 known species of beaked whales. Most species live in deep waters and do not approach boats. Scientists know less about beaked whales than about any other type of whale.
Belugas and narwhals
Belugas are white when fully grown. They are often called white whales. A beluga has 32 to 40 teeth.
Narwhals are grayish on top and whitish underneath. The whales have dark brown spots over the entire body. A narwhal has only two teeth. Among most males, the left tooth develops into a tusk up to about 10 feet (3 meters) long.
