Special Thanks
Our thanks to the folks at Ocean Alliance and Sea World Orlando for the tremendous photos they provided for this article.
In the world's great whale tales, including Herman Melville's "Moby Dick," the storytellers are preoccupied with one particular whale attribute: awesome size. Many whale species are staggeringly enormous. The blue whale, for example, can grow to 100 feet (30 m) long, about the height of a 10-story building, and can weigh as much as 150 tons (300,000 lb or 136077.7 kg). Its heart alone is the size of a small car, and there's enough room on its tongue for 50 people. It is the largest known animal in Earth's history.

Photo courtesy Iain Kerr, Ocean Alliance
A humpback whale, one of the most magnificent whale species. Humpbacks are known for their intelligence, playfulness and elaborate vocalizations.

But despite their monumental proportions, the most phenomenal thing about whales isn't how big they are: It's the way they live. Whales are mammals -- warm-blooded, air-breathing creatures -- but they spend their entire life in the ocean.Now, we'll look at the remarkable adaptations that make this possible. We'll also explore the mysterious behavior of whales, and we'll investigate the history of commercial whaling and whale conservation.

From the Land to the Sea
Whales are mammals, just like us, and more than 50 million years ago, their ancestors walked on land as we do. It's not clear what these animals were like, but some paleontologists believe they may have been hoofed mammals, something like modern cows. Other paleontologists believe that whales were more like modern wolves. Over the course of millions of years, the ancient creatures spent more and more time in the water, living partly on land and partly in the sea, like modern sea lions or otters. Eventually, the creatures stopped climbing onto land altogether, and they slowly lost their now-useless legs and fur. The evidence for this hypothesis is fairly compelling: Paleontologists have even found fossilized whale-like creatures with legs so small that they couldn't possibly support the animal's weight.

Modern whales have wide tail flukes, extended flippers and, in some species, dorsal fins. Whales swim forward by flexing their tails up and down, instead of side to side as with most fish. To change direction, they move their flippers, similar to the way an airplane steers (read How Sharks Work for details). The dorsal fins, if present, serve to stabilize the whale's body as it swims.

Photo courtesy NOAA
A humpback whale's tail fluke extends as it dives under the ocean surface. Whale researchers can track and identify individual whales based on distinctive tail markings.

To us, the path of these creatures from land to sea may seem like an odd turn of events. Why would a land mammal, specifically adapted for life on solid ground, evolve into a sea creature, spending much of its time away from air and sunlight? The best guess is that the whale's ancestors simply went where the food was. The ocean is filled with a wide variety of fish and crustaceans, while food along the coast can be scarce. Most likely, whale ancestors first ventured into the water to take advantage of this bounty.

To make this transition, whales had to overcome a number of obstacles. First of all, they had to contend with reduced access to breathable air. This led to a number of remarkable adaptations. The whale's "nose" moved from the face to the top of the head. This blowhole makes it easy for whales to breathe in air without fully surfacing. Instead, a whale swims near the surface, arches its body so its back briefly emerges and then flexes its tail, propelling it quickly to lower depths.

To breathe in air at the surface, a whale flexes a muscle that opens the blowhole and then inhales in the same way as any other mammal. When the whale relaxes the muscle, the blowhole closes, so it is safe to submerge again. Since they can only breathe at the surface, whales have had to develop conscious breathing. They do not have the automatic breathing processes that we do.

Contrary to popular belief, whales do not squirt seawater out of their blowholes. The spout people see is actually caused by exhaled air. Since the exhaled air is typically warmer than the surrounding air at the water's surface, it cools rapidly as it flows out. The water vapor in the air immediately condenses into a liquid, giving the appearance of spraying water. Since each species of whale has a uniquely shaped blowhole (and many have two blowholes), they also have their own distinctive spout shape. Experienced whale-watchers can identify a particular species by its spout alone.

In order to have much of a life in the ocean, whales had to be able to swim for long periods of time without coming up for air. To do this, they developed highly specialized respiratory systems. A whale's lungs work the same basic way ours do, but they make the most of each breath. In one breath, your body might absorb 15 percent of the oxygen you inhale. The whale, on the other hand, absorbs as much as 90 percent of the oxygen it breathes in (when you consider the immense size of a whale's lungs, that's a lot of oxygen per breath!). As in other mammals, whales store this excess of oxygen in myoglobin, a specialized protein cell found in muscles. Whales have greater amounts of myoglobin than other animals, which allows them to store larger amounts of oxygen at a time.

Photo courtesy Iain Kerr, Ocean Alliance
The eye of this right whale is about the size of a big grapefruit.

Whales also make more efficient use of this oxygen. When they dive, their heart beats more slowly and select arteries are constricted. This slows the flow of blood to certain organs without decreasing blood pressure. Essentially, a whale's specialized physiology gives it better "gas mileage:" They make each breath last. The sperm whale's respiratory system is among the most efficient in the world -- the huge animal can hold its breath for 80 to 90 minutes at a stretch. The beaked whale takes the prize, however. It can swim without a breath for as long as two hours.

Adapting to the lack of air was just one of the hurdles whales faced in moving to the sea. In the next section, we'll look at some of the other obstacles of life underwater and see how whales overcome them.

Blubber, Slumber and Pressure
Apart from the lack of breathable air, the most inhospitable element of the oceans is the extreme cold. Little sunlight penetrates the water's surface, and the temperature can drop below freezing even at relatively shallow depths. To deal with this biting cold, whales have developed a thick layer of blubber all around their bodies.

Blubber, a layer of stored-up fat beneath the skin and above the muscles, acts as a blanket to hold in the whale's body heat. In colder seasons, this insulating layer is the only thing keeping whales from freezing to death. Whales also use their blubber to store up energy for future use. Some species will feed heavily for half the year, when food is plentiful, and fast the rest of the year, living off their built-up blubber layer.

One of the less obvious difficulties of ocean life is getting a good night's sleep. Since whales must make a conscious decision to breathe, it isn't feasible for them ever to be completely unconscious. They might not wake up in time to take a breath! Marine biologists have determined that whales get around this problem by letting only one-half of the brain sleep at a time. In this way, the whale is never completely unconscious, but it still gets all the rest it needs.

Photo courtesy Iain Kerr, Ocean Alliance
This southern right whale is actually snoring. Click here to listen in!

We can't know for sure what this rest state feels like, but most likely, it is something like the semi-conscious state we experience as we begin to fall asleep. We're pretty close to unconsciousness, but have enough awareness of our surroundings to wake up completely if we need to. It's not uncommon to see a whale logging, swimming slowly along the surface with very little movement. Presumably, whales behave this way when they are at rest.

Another problem with ocean life is water pressure. Because of the pull of gravity, water exerts greater pressure at lower depths than it does at higher depths; essentially, you feel the extreme weight of all the water above you. Humans and other land mammals can only swim down to a relatively shallow depth before the increased pressure crushes their bodies. This is because the air that mammals carry in their lungs exerts only a certain amount of outward pressure (pressure from the inside of your body). As the difference between the outward pressure in the lungs and the inward pressure of the water increases, there is a greater force pushing in on the sides of the body. At a certain point, this force exceeds the structural integrity of the rib cage, and the rib cage collapses. Obviously, this would kill a human being.

Whales can withstand this pressure because their bodies are more flexible. Their ribs are bound by loose, bendable cartilage, which allows the rib cage to collapse to some degree under high pressure that would easily snap our bones. A whale's lungs can also collapse safely under pressure, which keeps them from rupturing. When the lungs collapse, the air inside them is compressed, maintaining a balance between inward and outward pressure. These adaptations are particularly important to sperm whales, which dive to depths of 7,000 feet (2,133.6 m) or more, hunting for the giant squid that live at these great depths.

Photo courtesy Ocean Alliance, photographer Chris Johnson
The lungs of a sperm whale (pictured here) can collapse as the whale dives to deeper depths for food.

In addition to adapting to the difficult conditions of ocean life, whales have also adapted to take full advantage of its rich resources. In the next sections, we'll look at some of the remarkable features that help whales catch their prey.

Feeding Time
All 75 species of whale are carnivores, but their hunting methods vary considerably. Toothed whales, such as the sperm whale and the killer whale (or orca), hunt in the same basic way as
sharks. They have a row of strong teeth, and they tear into their prey or swallow it whole. Many toothed whales eat only small fish and other easy-to-catch prey. Orcas, on the other hand, may attack sea lions, seals and even other whales. Like wolves, polar bears and other land predators, they track and stalk their prey, picking out a weaker target (such as a baby humpback whale). Orcas and other species usually hunt in packs, sometimes surrounding their prey. Despite these tendencies, orcas and most other toothed-whale species pose little threat to humans. In fact, many species seem to enjoy human company.

Photo courtesy Sea World Orlando
Two orca whales, commonly known as "killer whales." These toothed whales are among the most successful ocean predators, hunting in groups and feeding on everything from small fish to other whales. They are also one of the most intelligent and playful whale species, and seem to be quite fond of humans.

Some of these hunters have developed echolocation abilities to help them find their prey and locate any obstacles. Echolocation is a very simple concept: The whale emits a series of clicks (or other sounds) from its mouth or from organs in its head, and the sound waves travel out in the surrounding water. When the sound waves reach an obstacle or another animal, they bounce off of it and travel back to the whale. Water conducts sound very well, and whales have excellent hearing, so they may pick up even the faintest echoes from an object miles away.

In a volume of water with consistent pressure, sound will always travel at the same speed. By processing how long it takes the echo to return, the whale can calculate how far the sound wave traveled, and therefore determine how far away the object is. Like most animals, whales have two ears, one on each side of their head. This lets them determine the direction a sound is coming from. If the sound reaches the right ear first and is slightly louder in the right ear, the sound source is to the right; if it reaches the left ear first, it is to the left. In the dark world of the ocean, whales must sense their environment primarily through sound. In whales, a greater percentage of the brain is dedicated to processing aural information than to processing visual information. (In humans, the reverse is true.)

Echolocation is mainly found in toothed whales, such as dolphins and sperm whales, not their toothless cousins. The toothless-whale group -- which includes humpback whales, blue whales and many other species -- possess a unique feeding adaptation called a baleen. The baleen is a wide plate in the whale's mouth, made up of hundreds of long, fringed blades, composed of keratin -- the same material in our fingernails. These blades form a sieve that the whale uses to filter small animals -- such as krill, plankton and small fish -- out of seawater. Because of this unique attribute, toothless whales are usually referred to as baleen whales.

Photo courtesy NOAA
A humpback whale extending its baleen plate above the ocean surface

There are two groups of baleen whales, distinguished by the way they use theses sieves. Skimmers open their mouths and swim forward, catching fish, crustaceans and plankton as they go. After they've filtered a good bit of water, they knock any morsels loose and swallow them whole. Gulpers take in a mouthful of water and then push the tongue forward to force it all out through their baleen, catching any prey on the inside of the plate. Despite their large size, baleen whales typically have very small throats, measuring only a few inches across. This is all they need to devour the krill and other small creatures that make up their diet.

Since baleen whales filter water for their food, instead of ripping into their prey with sharp teeth, many people get the impression that they are passive hunters, simply cruising through the sea with their mouths open, snagging whatever happens to be in the way. But in fact, most baleen whales will seek out areas with high concentrations of food, and they may employ a number of tactics to catch their prey. Humpback whales, for example, trap fish with a sort of bubble net. When it has located a school of fish near the ocean's surface, a humpback swims in a circle underneath them, releasing air out of its blowhole. This builds up columns of bubbles all around the school, so they are contained in one small area. Then the whale charges up from below, catching the fish in its baleen. Humpback whales may also emit a loud shriek as they approach the fish, apparently in an effort to disorient their prey.

Humpback whales and other whale species can produce a wide range of sounds, which they use to communicate with each other over long distances. In the next section, we'll explore the noises whales make and find out what this might say about whale intelligence.

The Same Old Song
In the past hundred years, the world's attitude toward whales has changed drastically. The animals are no longer seen as fearsome creatures, as represented in "Moby Dick," and worldwide protection efforts have significantly reduced whale hunting. Through extensive observation, scientists have demonstrated that whales are generally peaceful, playful creatures, and that they posses a high level of intelligence. Today, whales seem pleasantly familiar to us, while in the past, they were monstrous strangers.

Photo courtesy NOAA
Male humpback whales are known for their long, vocal songs. A humpback's song can last as long as 30 minutes, and can be heard underwater miles away.

But even now, whales are still a mystery of sorts. A lot of information gathered by whale researchers has raised new puzzles about the animals. Whale communication is particularly perplexing. Male humpbacks (also known as bulls), the most vocal whales, emit a complex sequence of low moans, high squeals and clicking noises. These noises are sometimes combined in songs that last as long as 30 minutes. The astounding thing about these songs is that whales will repeat them over and over again, verbatim. And in a particular region, every male will sing the same song, making small changes every once in a while so that it evolves into a completely different song over time.

This behavior seems to be related to reproduction. During mating season, a male humpback starts the long song sequence, cutting it short only to join a passing female whale (also known as a cow), escorting her and her calf as they swim along. Eventually, the bull and cow may dive deep into the ocean, presumably to mate. It seems logical that the male's song is analogous to the bright plumage that birds display to attract a mate, except that the sound carries over many miles, attracting any other male humpbacks in the area. It's very odd that a male would call his own competition to him, unless he actually wanted to test his strength against others. Some whale researchers believe that the songs are actually acoustic contests of strength, similar to rams butting heads, or deer clashing their antlers.

Whales don't produce sounds the way we do. Our vocal-chord system wouldn't work too well underwater. Instead, whales produce sound by moving inhaled air around the nasal cavity in front of their blowholes. In toothed whales, the sound-making system involves a complex arrangement of fatty tissues. In sperm whales and dolphins, these sound structures are so large that they form a pronounced bulbous shape on the forehead. Scientists still don't understand exactly how whale sound production works, but they know it is unlike anything else we've encountered in the animal kingdom.

Humpback whales and most other species produce a wide range of sounds on a daily basis. In many species, whales seem to form close bonds with one another, and their calls may serve to let their companion whales know where they are and what they are doing. Water is an excellent fluid for conducting sound, and whale calls can be extremely loud, so they may communicate with one another over hundreds, perhaps thousands of miles. Whale experts are concerned that the noise pollution caused by boats, offshore drilling and other human activities in the ocean is drowning out these calls, shutting down the whale's long-distance communication system.

Name That Tune
A number of whale species make their own distinctive sounds. Click on the links below to hear various whale songs and sounds, recorded by researchers at the Ocean Alliance. (RealPlayer plug-in required).

These whale sounds (WAV files) were recorded by researchers at the National Oceanic and Atmospheric Administration. (These files will work with most media players.)

We still don't know what whales are actually saying to each other, but some researchers believe that whales possess sophisticated language capabilities. Whales have large brains, with the complex folds biologists associate with higher intelligence, but the extent of their abilities is not clear. Many species do exhibit highly intelligent behavior, both in captivity and in the wild, learning complex tasks and demonstrating advanced problem-solving skills.

Whales also have excellent memories, as is evident in their migration patterns. As we'll see in the next section, individual whales seem to remember specific points along the coast and throughout the ocean, returning to the same choice feeding spots year after year.

Long-distance Swimmers
One of the most intriguing aspects of whale behavior is the creatures' migration habits. Humpback whales in the Pacific Ocean will travel up and down the U.S. coast and out to Hawaii, returning to the same food-rich areas year after year. They tend to migrate with the change of seasons, taking advantage of the warmer waters nearer the equator during the colder months and the overabundance of food in the Arctic during the warmer months. Most whale species do not migrate regularly across the equator, so there may be separate collections of each species in the Northern and Southern Hemispheres.

Scientists study whale migration in a number of ways. In many species, whales have distinctive markings on their tails, which enable researchers to identify specific whales and track the sightings to get an idea of where and when the whale is travelling. Researchers also use satellite tags, cigar-sized radio transmitters that communicate with satellites to track a whale's location. Researchers embed the barbed transmitters in a whales back using a basic crossbow. Since the blubber is thick and the barb is fairly small, the whales are not hurt by the shot.

Transmitters have shown that some whale species travel much greater distances than scientists previously estimated. Researchers have tracked humpback whales traveling thousands of miles in only a few weeks, swimming from high northern latitudes to equatorial latitudes and back again. Male sperm whales seem to be solitary wanderers, traveling from ocean to ocean with no particular pattern. A single sperm whale might easily swim around the entire Earth in its 70-year lifetime.

In most other whale species, migration is closely connected to reproduction. Generally, the female whales (cows) mate in the fall or winter, when they are in warmer waters, and give birth in the same region a year or so later. In the summer, between mating and birth, the cow will take advantage of the rich food resources of the colder northern waters. This builds up the energy the cow needs to suckle its calf.

Photo courtesy Sea World Orlando
This baby orca whale is nursing from its mother. Whale calves drink an enormous amount of milk in the first months of life and may put on dozens of pounds a day.

Whale calves can swim as soon as they are born, and they rise to the surface to breathe soon after birth, but they need a lot of nurturing before they can venture out on their own. Depending on the species, whales may stick to their mother's side for a year or more before joining other young whales for extended play periods. For much of this time, the calf subsists only on its mother's milk. Cows have two teats, which are normally concealed inside slits behind the whale's abdomen, near the base of the tail. Whale milk is exceptionally rich, giving the calves the nutrients they need to grow to full size in a short period of time. A baby blue whale drinks 50 gallons (189 L) of milk every day and grows by as much as 10 pounds (4.54 kg) every hour. Of course, blue-whale calves are no shrimps to begin with. A newborn calf may measure 25 feet (7.62 m) from head to tail and typically weighs more than a full-grown African elephant.

Whales vary considerably in size, but most all species dwarf a human being.

Since the gestation and rearing periods are so long in most whale species, and the suckling so draining, cows only give birth every two to four years. This slow reproductive rate means that any substantial whale hunting may have a detrimental effect on whale populations.

In the next section, we'll take a look at a fascinating acrobtic feat performed by whales -- breaching.

One of the most spectacular behaviors in the animal kingdom is whale breaching. In this jaw-dropping acrobatic feat, whales weighing many tons build up enough velocity underwater to launch themselves above the ocean's surface, twist in the air and fall back, producing a tremendous splash.

Photo courtesy Iain Kerr, Ocean Alliance
This humpback whale is breaching, propelling itself out of the water and crashing back down again. Breaching is one of the most mysterious whale activities. Marine biologists aren't really sure what purpose it serves.

Whale researchers still aren't sure why whales do this, but they have a number of guesses. It may be that the huge splashing sound is used to communicate with other whales, especially when there is a lot of other noise underwater. Another idea is that the whales are trying to knock off crustaceans and other parasites attached to their body. Some researchers think breaching may be a demonstration of prowess, and that it could play some role in courting rituals. One of the most popular ideas is that whales breach simply for the fun of it. Most likely, breaching serves many different purposes that vary depending on the species and situation.

In the next section, we'll discuss the differences between whales and dolphins. Think of it as explaining the difference between two cousins in the same family.

Whale or Dolphin?
In some cases, scientists use the term whale to describe all animals in the order Cetacea. This includes large species such as humpback and blue whales, as well as smaller species, such as the bottle-nosed dolphin. Most of the time, people use the term "whale" only to describe the larger whale species, and refer to smaller cetaceans as dolphins or porpoises.

Photo courtesy Sea World Orlando
An orca mother and her calf. Orcas, commonly known as "killer whales," are members of the family Orcinus. Despite their common name, orcas pose very little threat to humans and even seem to enjoy human company.

Photo courtesy NOAA
A bottlenose dolphin mother with her calf. Dolphins, which make up the family Delphinidae within the order of whales, are thought to be among the smartest animals on Earth.

Dolphins, which make up the family Delphinidae, are toothed whales characterized by their relatively small size, bulbous head and beaked snout. Orcas and pilot whales are also included in this family, though they are much larger and their beak is less pronounced. Porpoises, members of the family Phocaenidae, are small toothed whales that have a rounded head rather than a beaked snout.

In the next section, we'll explore the history of whale hunting and conservation to see how the relationship between whales and people has evolved over the years.

Whalers and Conservation
In the past, the main contact that humans had with whales was in hunting them. In some cultures, whale meat was a major food source dating back to prehistoric times. Whales were highly prized game because, like the woolly mammoth or bison, a single kill yielded an incredible amount of meat. But by the 1700s, when worldwide whaling really took off, the focus had shifted from the meat to a rich oil derived from whale blubber. Since it was the primary lamp fuel in many parts of the world, whale oil was big business throughout the 1700s and into the 1800s.

Photo courtesy NOAA
The deck of an early 20th-century whaling vessel. Whaling was once big business in the United States, Russia and many other countries throughout the world.

In this era, whale baleen was also highly prized. The keratin material, commonly referred to as whalebone, combines great strength and flexibility. These qualities made it an ideal choice for a variety of products, including ladies' corsets, riding crops and umbrellas. Whale teeth, engraved with inscriptions and decorations, were also very popular, particularly among the upper class.

The surge of whaling in this time had a profound impact on many whale species. Since whales only reproduce once every year, or, in many species, once every few years, they are devastated by excessive hunting. A female whale might live 50 years or more, giving birth to dozens of calves in that time, so the loss of even one female whale has a far-reaching effect on the entire population. Additionally, reduced whale numbers upset the sea's ecological balance, leading to an overabundance of krill in many areas, which can lead to population booms in other species that feed on the creatures.

With the invention of the harpoon gun and the increased speed and mobility of steam-powered boats, whalers could take aim at crafty species that had eluded them before. This, along with the rising popularity of whale-oil cosmetics, led to an unprecedented period of whaling in the late 1800s and early 1900s. By the 1940s, it was clear that some whale species were nearing extinction. To secure the future of the industry, the major whaling nations bound together in 1946 and signed the International Whaling Convention. As part of this agreement, the nations established the International Whaling Commission, an independent organization charged with researching whale populations and regulating whaling practice.

Over the years, the commission instituted even stricter regulations on whaling practice, in light of new evidence that whale populations were still dwindling. In 1986, the commission instituted a worldwide moratorium on whaling, as it had become clear that any widespread hunting could lead to species extinction. Today, the commission only allows for small-scale hunting by certain aboriginal cultures and hunting for scientific purposes. Some nations, most notably Japan and Norway, continue to allow commercial whaling, claiming that they are only controlling regional whale populations.

Photo courtesy NOAA/NMFS
Right whales, so named because they were the "right whale to hunt," are among the most endangered whales today. Researchers estimate there are only a few hundred left in the world. This right whale was named "Calvin" by the New England Aquarium researchers who tried to disentangle her from fishing gear in early 2001. The researchers were unable to free the whale, but attached a satellite tracker to the gear so they could monitor her path. In June of 2001, some time after the tracking device failed, Calvin was spotted , free of the gear. Click here to see where Calvin has traveled since being discovered.

Under these regulations, many whale species have bounced back from the brink of extinction, but others, such as the right whale, are still in serious danger. According to whale-conservation organizations, the survival of these species depends on even stricter whaling regulations and more vigilant campaigns against illegal whaling operations. If these conservation efforts succeed, endangered whale species have a good shot at replenishing their numbers and continuing their mastery of the oceans for another 50 million years.

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