Kingdom: Animalia (animals)

Phylum: Chordata (vertebrates)

Class: Mammalia (mammals)

Order: Cetacea (whales and dolphins)

Suborder: Mysticeti (baleen whales)

Family: Eschrichlidae

Genus: Eschrichtius

Species: robustus

Gray Whales are medium sized whales, reaching up to forty-five feet in length. Females can weigh as much as 70,000 pounds; males are slightly smaller, as is the case with all baleen whales. Gray Whales reach maturity at eight years, and growth stops at age forty. Their life expectancy is fifty to sixty years. The oldest recorded Gray Whale was seventy-seven years old. Their skin is gray with white patches, which mostly consist of areas where barnacles and lice have attached themselves to the skin. They have no dorsal or back fin. Instead, they have a low hump and a series of six to twelve "knuckles" or bumps. The Gray Whale is a baleen whale, and has approximately three hundred plates of cream-colored baleen hanging from its upper jaw (the Humpback Whale, by contrast, has black baleen). Gray Whales have two to four throat grooves, about five feet long each. These grooves allow their throat to expand during the huge intake of water during filter feeding.

Gray Whales are the slowest swimmers among all whale species, which may account for the large clusters of whale lice and barnacles which colonize their skin. The parasites on their skin can include hundreds of pounds of barnacles and whale lice. The skin of the Gray Whale is actually black or slate-colored (newborn calves are black); the whales get their name from the mottled grayish patches of barnacles and scars left by barnacles and other parasites. Barnacles burrow into the surface of the skin to stay attached, and after they fall off (often when the whale enters colder polar waters), they leave a distinctive marbled and scarred area. Older whales have more of these marbled markings, as they have had the most parasites.

Generally, there are little or no parasites on the right side of the Gray Whale's body, because that's the side that gets scrapes along the ocean bottom when the whale is feeding. Because of this feeding pattern, the baleen plates on that side of the mouth also become more worn and are generally shorter than those on the left. Barnacles generally get their start growing on the whale's skin in the warm waters of the southern part of the Gray Whale's range, but drop off when they migrate north in the summer to the cold waters of the Arctic. Some Gray Whales have been seen taking "showers" at the foot of cliffs from which fresh water pours into the sea, to kill the saltwater barnacles. Barnacles do not generally colonize the skins of the faster, larger whales such as the Blue and Fin Whales. These larger whales also share the trait of shedding huge sheets of dead skin, periodically sloughing off any parasites which may have attached themselves.

Gray Whales have a layer of blubber up to ten inches thick. There are hairy bristles (vibrassae) on the Gray Whale's snout and the front of the head. These are used as tactile sensors, like cat's whiskers. Unlike humans, whales have to think about breathing, therefore they cannot sleep the same way we do; they would drown. Whales sleep by floating on the surface of the water and shutting down only half their brain at one time. Gray Whales sleep with their blowholes just exposed on the surface of the water. During their extended migration they swim day and night, without sleeping. The Gray Whale normally swims about five miles per hour, or approximately the speed of a child on a bicycle. However, Gray Whales can reach speeds of ten to eleven miles per hour in bursts when in danger. Feeding speeds are slower, about 1-2.5 mph.

Gray Whales breathe air at the surface of the water through two blowholes located near the top of the head. When warm, moist air exhaled from the animals' lungs, meets the cool air at the ocean surface, it creates the bushy column known as a blow, or spout. The spout of the Gray Whale is a noisy stream that can be heard half a mile away. A Gray Whale's blow is up to fifteen feet high and each blow is visible for about five seconds. Generally, Gray Whales will dive for three to six minutes, then surface for three to five blows in row, thirty to fifty seconds apart, before diving deep for three to six minutes again. Before making a long, deep dive, a Gray Whale often displays its twelve-foot-wide fan-shaped flukes, or tail. Orcas (killer whales) are a cause of Gray Whale deaths, and Orca teeth scars can sometimes be seen on the Gray Whale's flukes. These flukes have no bones and connect to the body and tail muscles by banks of tendons. After the whale submerges one can sometimes see an elongated, smooth oval of calm water, known as a footprint, where the whale has been.

Gray Whales are very agile swimmers. They can dive for up to thirty minutes and go five hundred feet deep, but they can also swim in even relatively shallow water without running aground. Gray Whales sometimes breach, jumping partially out of the water and falling back at an angle, splashing and making a very loud noise. This may help clean off some of the encrustations of parasites, or in communicating with other Gray Whales, or they might just plain enjoy it. Gray Whales emit grunts, clicks and whistling sounds, which may be used in communicating with other Gray Whales. Spyhopping is another Gray Whale activity in which the whale pokes its head up to ten feet out of the water, turning around slowly, to take a look around. Gray Whales congregate in small pods of about three whales, but the pod may have as many as sixteen members. Large groups (hundreds of whales) form in feeding waters, but these are loose, temporary associations and they do not form long-term bonds.

Gray Whales have the longest migrations of any mammal. They spend summers in cold polar waters and migrate south to Baja Mexico in the autumn and winter. They arrive back off the coast of Alaska again in spring, from April to May, and stay there until November, leaving before the waters freeze over. They then spend two months traveling towards Baja California, where they spend the winter calving and mating. During summer, they spend all their time in the Arctic in areas rich in their food. The extended daylight of the long Arctic days causes the tiny plants and animals to grow quickly and abundantly. Dense concentrations of krill and plankton can extend over several square miles of ocean there; this provides a very rich food resource for the whales, who gorge themselves 24 hours a day storing up fat as blubber for the rest of the year.

Gray Whales pack a whole year's feeding into these four or five summer months. During this time, their weight may increase by 40 percent, which is stored as blubber for the long migration to the winter breeding ground. As autumn approaches, there is less sunlight, less food, and the water turns cold. This is when they travel to Baja California, where they congregate in lagoons to give birth and mate. Pregnant female Gray Whales lead the annual migration. By migrating every year, whales can take advantage of the seasonal abundance of food found in cold regions and the nurturing climate for giving birth and rearing young in warm regions. Splitting the year between north and south gives the whales the best of two worlds. Summer feeding is better at higher latitudes because the long days produce lots of phytoplankton (small marine plants), which are eaten by zooplankton (small marine animals). Together these are the basic food for all ocean life, stimulating the growth of the marine food web including bottom dwelling amphipods, the primary prey of Gray Whales.

In December to early February, the California Gray Whales are migrating south. They swim at the same speed night and day during the migration, and do not stop to rest (when they reach the winter breeding grounds, they frequently take half-hour "naps" six or seven times a day). Gray Whales can be seen passing by California in December and January during their southern migration and again in March and April on their northern journey. Beginning in February one begins seeing whales migrating back to Alaska with their newborn babies by their sides. There is sometimes what appears to be an overlap in migration patterns with some whales still heading south while others are moving north. Unlike most other large cetaceans, Gray Whales are generally associated with the continental shelf, and are truly a coastal species. On their northern migration they swim close to shore, with their babies on the shore side. It is thought that this is to protect them from attacks from Great White Sharks. This is often when the best viewing can take place because they are moving more slowly because of their young calves and also they are swimming against the current.

Since Gray Whales migrate relatively close to shore, whale watching for them has become very popular. In recent years, "friendly whales" have been encountered in San Ignacio Lagoon in Baja California in Mexico. Here, Gray Whales will sometimes swim near small skiffs and allow themselves to be touched. Concern has grown about the impact of boat traffic around whales and the number of boats allowed in the breeding lagoons is restricted. Along the migration route, boats' proximity to whales is similarly limited.

Not all whales travel to the lagoons during the winter. Some may travel a portion of the way, some may not at all. There is a small population of eastern Pacific Gray Whales that do not migrate. These live year-round in the coastal waters off Vancouver Island and Washington. Every state and province along the migration route claims a small summer resident population. These whales seem to be stopping short of the final destination and are thus able to begin feeding earlier in the summer and continue later into the fall before heading south again. The Central Oregon coast, for instance, hosts about four to five hundred resident Gray Whales every spring and summer.

After four summer months in the Bering and Chukchi seas, the move south begins with pregnant females leading the way, and other adults and yearlings following. They cross the Gulf of Alaska at a rate of about 185 km per day. They are first seen from land in late November and early December in Oregon and Northern California, arriving off San Francisco in mid-December and San Diego at Christmas time. The migration takes two routes off Santa Barbara, with some whales taking the island route on to Guadalupe and Socorro, and the rest hugging the coast. Most whales go into Scammon Lagoon and San Ignacio Lagoon on the western shore of the Baja Peninsula, but some go on to the area of Jalisco inside the Gulf of California. The migration north begins in February and overlaps near San Diego with the last few stragglers still coming south. The northern movement is slower (because of the currents and the presence of young calves) with an average rate of eighty kilometers per day. Females with calves tend to stay close inshore, but most whales follow a more westerly route north, heading out from the coast and massing off the Olympic Peninsula in Washington before setting off on a circular navigation route to the Aleutians.

Gray Whales feed differently from other whales. They stir up shallow coastal areas, sucking in the bottom dwelling animals, mostly amphipods (which are related to shrimp). Muddy plumes of water are often seen in places where Gray Whales are feeding. Gray Whales (like all baleen whales) are seasonal feeders and carnivores. The primary behavior of Gray Whales during the summer months is feeding, so their spatial distribution is a function of the location of their prey. Different types of prey live in different microhabitats in the feeding grounds, and Gray Whales have been observed switching between various types of prey, moving between various biozones during the summer season. They are bottom feeders (benthic feeders), and sieve through the mud on the bottom of the ocean floor with their baleen. They filter out small shrimp-like crustaceans such as amphipods, krill and copepods, as well as plankton and mollusks, and sometimes squid and small fish. Their baleen strains out the nourishing organic material and the whale spits out the mud. The tongue loosens the amphipods and other tiny food from the baleen plates and the whale swallows the food. The huge, narrow, pink tongue of the Gray Whale weighs about 1-1.5 tons.

Gray Whales do forage for some food in the lagoons of Baja California during the winter, eating shellfish, mollusks and small crustaceans. The whale turns on one side (usually the right) and plows through the silt in a long trench through the top layers of the mud, stirring up both sediment and the creatures that live in it. By careful timing, Gray Whales know just when to scoop up the animals swimming away, while giving the heavier sediment enough time to settle out. They then rise to the surface and, with their heads sticking out above the water, sort out the excess mud and sand from the food with their tongues. Sometimes one can see "muddy" water near the Gray Whale's head when it surfaces from a feeding dive. Since Gray Whales filter animals from mud and water, their baleen is stiffer and has coarser fringes than that of other baleen whales, which filter animals from water only. Sometimes their feeding takes them into very shallow water just outside breaking waves along shallow, sloping sandy beaches. This often results in false stranding calls from concerned people who assume the animals are in trouble. In fact, they are feeding in the furrows you sometimes can see in these areas during low tide. During migration and while in the warm breeding waters, Gray Whales eat very little and live off their thick layer of blubber. Thus, many whales may go without food for up to five months.

Ancient whales all had teeth, but some evolved plates of baleen from the curved palatal ridges found on the roof of the mouth (like the ones in your own mouth). Baleen is made of keratin, the same material as hair, and it forms like a skin, with strong fibers embedded within soft tissue. As the whale grows older, the softer material is rubbed away, exposing the tough baleen fibers. Modern baleen whales still develop rudimentary teeth in their early fetal stage of growth, but these tooth buds do not develop.

Not all baleen whales have the same sort of baleen. How coarse or fine the baleen of a particular species of whale is depends on what that whale's primary food is. The Fin Whale, for instance, eats tiny plankton, and has baleen that is as fine as wool. The Blue Whale eats larger shrimp (krill) and small fish, and has coarser baleen, with the plates spaced wider apart. Among baleen whales, there are two basically different ways of feeding: gulping and skimming. Gulpers take in one huge mouthful and close their jaws to strain the krill from the water. A Blue Whale can take in 66 tons of water in one gulp. Skimmers, on the other hand, glide through the water with their mouths slightly open, causing a current of water to flow into their mouths and out through the baleen filters. Skimmers generally feed on smaller prey (such as plankton and krill) than gulpers, who often feed on fish and larger crustaceans. Baleen whales do not chew; they swallow their food whole. The whale's intestines are much longer, proportionately, than those of any other land mammal. The human intestine is five or six times the length of a person's body, while the intestines of a Sperm Whale is twenty-four times its body length. In a 55-foot whale, this works out to over one thousand feet of intestines.

Female Gray Whales usually give birth every two to three years, with a gestation period of 418 days. The whale calf is born head first (unusual for cetaceans) and is twelve to fifteen feet in length and weigh about 1,500 pounds. Gray Whale breeding occurs mostly in the winter to early spring while near the surface and in warm waters. The newborn instinctively swims to the surface within ten seconds for its first breath; it is helped by its mother, using her flippers. Within thirty minutes of its birth the baby whale can swim. Twins are extremely rare; there is almost always one calf. Calves are weaned at about eight months, after they have journeyed with their mothers back to the northern feeding grounds. Gray whales don't give birth in the open ocean; they require shallow water, a protected lagoon and warm temperatures. Going south into temperate or subtropical waters to calve is typical of most baleen whales and presumably helps the newborn whales conserve body heat. The whales favor lagoons because they are protected areas of calm, warm water. Mexican fisherman also report that there are few sharks in the lagoons at the times when the whales are present. When a female Gray Whale is about to give birth, she retreats to an isolated, shallow spot of a lagoon where the water is warmer and the salinity higher. The increased salinity provides additional buoyancy for both the birthing mothers and the struggling newborn.

The male takes none of the responsibility for newborns. Females have two teats, one on either side of the genital slit. On the day of its birth, a baby whale is already as big as an adult bull elephant. It has no baleen plates, and relies on its mother's milk. When a baby whale nurses, a muscle in the mother's breast contracts and sends out a jet of milk under sufficient pressure to carry it straight up in the air six or seven feet. The baby is nurtured with its mother's extremely rich milk, consisting of 53% fat (cow's milk has 3.5% fat), and is weaned in about eight months. Calves begin to acquire independence during the last third of the suckling period. The calf grows at an incredible rate: every day it drinks over 100 quarts of milk and puts on 230 pounds of new weight, or almost 10 pounds every hour. A ton every nine days. The mother and calf may stay together for about a year. The extremely fatty milk helps to conserve water for the mother and makes feeding easier for the calf; the milk makes a compact "glob" that sticks to the calves' baleen. Calves usually are rambunctious but stay close to their mothers as they become more coordinated and develop an insulating blubber layer. Calves are at least a month old before they migrate north with their mothers.

Gray Whales have returned from the brink of extinction. In the late 1800s, the Gray Whale breeding grounds were discovered and whalers decimated the population. By the 1890s, the Gray Whale was almost extinct and most hunting stopped. The drop in population made it no longer profitable to hunt Gray Whales; they were left alone and their numbers recovered. However, the early 1900s brought the invention of factory ships, which processed whales aboard the vessels. This new technology allowed intensive hunting on the grays once again and their population again dangerously dropped to probably fewer than two thousand individuals. In the 1920s, they were again commercially targeted and once again brought to the verge of extinction. There probably were only a few hundred individuals left when they were finally protected by international agreement in 1946. Commercial whaling was banned in 1951 and the Gray Whale earned endangered species status in 1973. Since that time, the population has grown to over 22,000. As a result of this population recovery, Gray Whales were removed from the endangered species list in 1994.

The fact that Gray Whales congregate together in the winter for mating and calving has been partially responsible for both their difficulty and their recovery. When commercial whalers first discovered the calving lagoons, the concentration of whales in the shallow waters made their wholesale slaughter very easy. The predictability of the Gray Whales' movements up and down the coast made it possible for whalers to exploit them heavily along the migration route. Around 1855, shore processing stations were set up in San Diego. At that time, navigation inside the bay was judged hazardous because of the abundance of breeding whales. Mothers are very protective of their calves and earned the name "Devilfish" from early whalers in the lagoons because of their violent defensive behaviors.

Today, Gray Whales are found only in the Pacific. A separate population is found in the waters of Korea and Japan, and is close to extinction with less than fifty individuals. A population of Gray Whales once lived in the North Atlantic Ocean and became extinct in the 1700s due to hunting. Old bones from these whales have been found along the Florida coast.

In June 1994, the eastern North Pacific Gray Whales were removed from the List of Endangered Wildlife under the Endangered Species Act because of their substantial recovery over the previous forty years. The Endangered Species Act requires that species removed from the list be monitored for a minimum period of five years and its status reassessed at the end of that period. The delisting of the Eastern North Pacific stock of Gray Whales does not alter the status of the still-endangered Western North Pacific ("Korean") stock of Gray Whales. This population will be monitored for an additional five years (1999-2004). There is no allowable commercial take of Gray Whales; still, the status of the western Pacific population is relatively unknown, and is believed to be highly endangered and close to extinction. Korean Gray Whales are also migratory, with a long-distance traveling pattern very similar to the California Gray Whales. The feeding habits and behavioral traits of these two different populations indicate that they are discrete geographical populations which do not intermingle. The Gray Whale is an interesting case study because one population is extinct (Atlantic), one is endangered (Western Pacific) and one is recovered (Eastern Pacific). The Eastern Pacific Gray Whales represents one of the Endangered Species Act's success stories.

Many Gray Whales have been sighted inside Puget Sound this year, which is unusual for them. It's possible that they are there foraging because there is a food shortage this year, perhaps as a result of La Niña. Many dead Gray Whales have been washing ashore on the western coast of the United States lately; most of these dead whales have been juveniles, many showing signs of starvation. On three-year old whale that came ashore in Washington State was twenty-nine feet long, had a thin layer of blubber and was clearly underweight. With the whale population so large, several hundred whales would be expected to die every year from disease, starvation and collisions with boats. Still, despite incomplete statistics, researchers estimate that the number of whales beached this year is the highest they've seen.

Commercial whaling is regulated by the International Whaling Commission, which voted to phase out all commercial whaling in 1982. Not all whaling nations agree with the ban, however and the commission's ability to enforce prohibitions is limited. Norway withdrew from the commission and resumed commercial exploitation of Minke Whales in 1994. Both Norway and Japan kill whales ostensibly for scientific purposes, although many observers believe that the true purpose of this continued whaling is commercial use. Whale meat now sells for about $300 per pound in Japan, and a recent DNA survey of whale meat for sale in Japan showed that nine out of sixteen samples, more than 50 percent, came from endangered whale species that are internationally protected.

Pollution poses a threat to whales around the world. Chemical contaminants in the water and in whales' food sources may accumulate in their systems and because they are long-lived, may reduce longevity and reproduction. Oil is another kind of chemical pollution that can harm whales. Twenty-nine Gray Whales were reported stranded in Alaska near the area of the Exxon-Valdez oil spill in 1989. Whales may ingest contaminated prey and sediments, or contact with oil may impair the filtering efficiency of their baleen. Another important concern is that air pollution has depleted the ozone layer above the Antarctic. Reduced ozone levels allow more harmful ultraviolet radiation to reach the southern seas and this increased radiation may harm the phytoplankton and krill that the whales depend on for food. Exposure to increased ultraviolet radiation also probably accounts for the skin lesions observed recently on whales in the area.

Shipping poses a threat to some whale species. The North Atlantic Right Whale, for instance, is highly endangered and collisions with ships in the southeastern United States are killing one or two whales per year. Although this loss may not seem like much, it is having an effect because the species has only about three hundred individuals left and produces only ten calves each year, several of which die of other causes. Spotter planes are now flown over key areas where the whales gather and the pilots radio ships to warn captains to steer clear of the whales.

Commercial fishing can have a negative impact on whales in two ways. Overfishing has heavily depleted many fish stocks around the world and removing food sources can harm the whales that depend on those fish. Whales also can become entangled in fishing nets and drown because they are air-breathing mammals. Coastal development also can pose a threat to whales that depend on near-shore habitat. Offshore drilling for oil and gas can cause increased noise disturbance, pollution and threats from shipping. Dredging and vessel traffic associated with a salt extraction plant in one of the Mexican lagoons used by Gray Whales for breeding caused the whales to abandon that area in the 1960s. When the plant was closed the whales returned.

The physical size of the whale is itself a biological adaptation which serves them in many ways. Their great size confers protection against predators. The great bulk of the whale's body results in a reduced surface to volume ratio, helping them to maintain a the balance of their body temperature. Also, among the baleen whales, the larger species are able to feed more efficiently than smaller whales, as they take in a greater volume of water (and food) with each mouthful, in relation to their body size. Efficiency in feeding is therefore a major biological advantage associated with size: a very large Blue Whale would only need to take in 100 gulps of seawater and krill for every 300 that the much smaller Minke Whale must take.

Large bodies also conserve heat. Heat loss from a body in water is about 27 times faster than in air, so whales face more of a metabolic challenge maintaining a stable core body temperature than land-dwelling mammals. The size of the whale itself is an adaptation to living in water and conserving heat. One crucial factor in heat conservation is the whale's surface to volume ratio. As the overall size of a body increases, the ratio of its volume (the body of the whale itself, where heat is generated) to its surface (the skin of the whale, where heat is lost) goes down. Here's an easy way to picture this principle: think of two cubes, one with 1-inch sides, and one with 2-inch sides. The 1-inch cube has a volume of one cubic inch and a surface area of 6 square inches (a surface to volume ratio off 6). A cube twice its size (the 2-inch cube) has a volume of 8 cubic inches and a surface area of 24 square inches, which is a surface to volume ratio of 3. This natural thermodynamic principle is also the reason many species grew so huge during the ice age (woolly mammoths, gigantic cave bears, giant ground sloths), because it gave them an adaptational advantage in the cold climate over smaller animals.

Being warm-blooded, whales must expend a certain amount of energy to maintain a stable body temperature. Land mammals use fur as an insulator, which would be a drawback on a whale (although it would look fabulous). Instead, the whale uses a thick layer of blubber to insulate its body. Bowhead Whales, which live in the Arctic, may have a layer of blubber as thick as 20 inches, and a skin eight times thicker than whales that live in warmer waters. The thickness of a whale's blubber layer varies seasonally. In combination with air in the whale's lungs, the fatty and buoyant blubber makes it possible for a whale to float. In addition to the blubber, fat may be stored in organs such as the liver, in the muscle tissues, or inside bone in the form of oil. Oil and fat may account for 50% of a whale's total body weight. If a whale loses too much blubber and gets too thin, it must expend more and more energy to stay afloat. Likewise, a whale that is too fat has more buoyancy than can easily be overcome for diving and swimming.

The arrangement of the whale's circulatory system itself is another adaptation to minimize heat loss in the cold ocean. In the whale, veins and arteries cluster together and run alongside each other, functioning as heat exchangers. Colder blood returning from the outer parts of the whale (through the veins) absorbs heat from the warmer blood in the arteries, which is being pumped away from the heart, and carries this warmth back into the whale, instead of dissipating it out at the skin.

Anatomists and evolutionists refer to the whale's tail (flukes) as a neomorph (new shape). This means it is a new bodily structure that has appeared over the course of evolution, rather an existing structure becoming modified, such as when "wings" evolve from structures that used to be "arms". The tail of the whale did not evolve from their hind legs. Whales evolved from land-dwelling mammals, and their hind limbs have disappeared (become vestigial). There are, however, still traces of the old external limbs reflected in the whale's skeleton. And, occasionally, a whale is found with more extensive remnants of these ancestral legs, such as the Humpback which was discovered to have vestigial hind legs sticking out more than a yard from its underbelly. These legs contained separate bones and cartilage corresponding to the original limb segments, and are the result of ancestral genetics which persists in whales to this day. As mammals, whales still retain some hairs in specialized places on their bodies. Clusters of hairs or vestigial follicles still exist around the lips and chin, and around the blowhole. These hairs are usually no longer than half an inch, but are sufficient to pick up vibrations in the water and serve an important sensory function, much like the whiskers of a cat. In baleen whales these hairs may serve as vibration receptors which the whale uses to feel out the tiny kicking crustaceans as it plows through a swarm of krill. Over the rest of the whale's body, its mammalian hair has entirely disappeared, as have the follicles.

Whale skin secretes tiny droplets of a natural polymer which assist in the shedding of epidermal skin cells, reducing turbulence and drag in the water. When water moves past the whale's skin, the particles of fluid in the immediate vicinity of the body are held on to and retarded in their motion. The fluid layers nearest the body are retarded most, with the effect decreasing farther out from the surface of the skin. The outer layers of water glide over one another in what is known as laminar flow, an effect which allows the whale to swim more efficiently. Divers who have had whales swim very close to them say there is enormous turbulence from its passing, and the tail stirs up such a great trail of waves in its wake that without even being touched by the tail, the diver can be knocked around very violently, just from the water displacement.

Whales do not get the bends during deep dives, as human divers may. When a diver descends, breathing compressed air, the pressure of the air in his lungs counters the water pressure on him from outside, preventing his lungs from collapsing. But at great depth and pressure, nitrogen dissolves into the blood and tissues of his body. When the diver ascends, and the pressure decreases, this nitrogen bubbles out, causing excruciating pain (the bends). A whale, however, takes very little air down with it when it dives. Its lungs are comparatively small, and collapse easily and naturally with increased water pressure. The air from the lungs is forced into nasal and sinus cavities, where thick membranes prevent gas exchange into the tissues. Nitrogen in the air inside a whale never gets a chance to dissolve out into its blood and tissues, and it avoids this problem associated with deep diving. When a whale surfaces, the lungs gradually expand again, and the blowhole is forced open, expelling the air. The whale is very efficient in its rate of respiration: with each deep breath, 80 - 90% of the air in the lungs is exchanged, compared to 20% in humans (one inhalation for a whale is proportionally equivalent to eight in a human).

Water propagates sound much more efficiently than does air. Sound is used by whales for two major purposes: for echolocation and for communication. The large baleen whales make use of low frequency sounds, apparently for communication, which have the feature of carrying extremely long distances underwater. Differences in water densities, salinity, temperatures and ocean currents produce distinct layers in the ocean, or channels, at specific depths. These channels can trap sounds (like speaking through a cardboard tube), and tunnel them along for very great distances. Using deep ocean channels, whales may be in communication over tens or even hundreds of miles. Propagation of low-frequency whale noises via deep ocean channels can reach 5,600 kilometers, although background noises increase interference. Humpback Whales appear to use these deep sound channels to transmit their sounds. It seems likely that Humpback Whales intentionally choose a particular place and depth which is favorable to the transmission of their sonic emissions.

The Sperm Whale is a creature of the open ocean, and is found only in waters deeper than 3,500 feet. They are found in all the oceans of the world. Females and calves tend to stay in warmer waters, while young males may live in groups in cool temperate waters. Only solitary adult males travel all the way to the cold polar seas of the Arctic and Antarctic. Males make long migrations to mate with females. The Sperm Whale was built for depth, not speed, and swims slower than many other whales at four miles per hour (a fast walking pace). Sperm whales generally travel in groups, unlike the larger baleen whales (Blue and Fin Whales), which generally travel singly. In groups, Sperm Whales often repeat slow patterns of clicks. When one whale produces a particular pattern of clicks, another whale may repeat it in turn. The Sperm Whale has the largest brain which has ever evolved on this planet, and it is entirely possible that they use these clicks to communicate information to each other. Because the Sperm Whale does not migrate seasonally between separate feeding and breeding grounds, there is no evolutionary advantage to restricting gestation to a period less than a year. Unlike the baleen whales, Sperm Whale gestation may last 16 months, and the calf may nurse for up to two years. Adults reach lengths of sixty feet and can weigh fifty tons. One was measured at ninety feet long.

The Sperm Whale is the only whale with one blowhole (all other whales have two). Among Sperm Whales, only the adult males have teeth, and only on the lower jaw. The teeth may be eight inches long and weigh seven pounds, and fit precisely into sockets in the upper jaw. Large toothed whales dive deep in search of food. For the same reason, baleen whales are not known to be deep divers, as the plankton and krill they eat usually are not found more than 300 feet deep. Squid are an important diet of many whales. Some non-baleen whales which feed on squid are entirely toothless, and catch squid by sucking them into their mouths and swallowing them whole. The Sperm Whale has the most specialized diet of all whales, feeding on giant squid at depths of more than 1,000 feet. By diving to these incredible depths, it has access to a food resource which is out of reach of, and too large for, any other predators. There are thousands of species of squid, including giant deep-water squid which grow to 40 feet in length. A male Sperm Whale eats more than a ton of squid a day. The largest squid ever found in a Sperm Whale's stomach was 40 feet long and weighed 400 pounds. The whale that ate it was 45 feet long. The horny beaks of the many squid eaten by the Sperm Whale accumulate in its stomach and are regurgitated as a floating mass called ambergris (gray amber). Whalers looked for ambergris inside the stomachs of Sperm Whales they had killed, where it was found as a ball-like concretion which hardened on exposure to air. It was worth its weight in gold in whaling days, and is still used by the perfume industry as a base to carry fragrances.

The Sperm Whale has been known to dive to depths of 3,000 - 5,000 feet, and occasionally as deep at 10,000 feet. At this depth there is no light, and the sperm whale locates its prey by echolocation. Specialized bones in the skull of the Sperm Whale are curved in such a way as to focus sonic waves produced inside the whale's head. The waxy spermaceti which fills two large cavities inside its head may also act as a giant acoustic lens to focus sonic waves. These blasts of sound can be very intense and localized, and may be used to stun and disable their prey. A Sperm Whale's angle of hearing is thought to be perpendicular to his body, and they keep an ear tuned towards the ocean bottom. If the constant CRACK-CRACK-CRACK of their echolocation signals indicates the presence of squid at 2,000 2,500 or 3,000 feet below the surface, they dive vertically and go straight after their prey. When the Sperm Whale dives it goes straight down, lifting its tail high in the air (most other whales dive down gradually, at an angle).

Great size is an advantage in deep diving; the larger an individual whale, the better it is able to withstand the pressures and stresses of the depths. In practice this means that adult male whales are more proficient in diving than young whales, or females. Apart from the problems faced by very high pressures at these depths, one might wonder how the whale manages to swim, since muscles require oxygen to function, which would be used up quickly on a single breath of air. Whales, however, have unusually high levels of myoglobin in the muscles, a substance found in blood which combines with and stores oxygen. Sperm whales are particularly efficient in storing oxygen this way, absorbing up to half their total oxygen store in the muscles (twice as much as land mammals). Sperm Whale muscle tissue is colored almost black with this myoglobin.

Sperm Whales have been observed floating motionless deep in the water. This means the whale has achieved neutral buoyancy, which would vary with differing depths. It is thought that Sperm Whales are able to adjust the buoyancy of their bodies. The spermaceti which is found in the head of the Sperm Whale may be used by the whale to control buoyancy and therefore help in diving. Spermaceti is not an oil or a fat, but a natural wax which is liquid at body temperature. Spermaceti, when cooled, solidifies and shrinks, becoming denser. This brings about a negative buoyancy for the whale, which then descends in the water. It has been suggested (but not proven) that the Sperm Whale takes cold water into its sinuses and nasal passages, which cools the spermaceti and achieves negative buoyancy. When the whale wants to ascend, it forces the cold water out of the nasal cavities and blood circulation warms the spermaceti to its liquefied, buoyant state, causing the Sperm Whale to rise. The Sperm Whale usually dives and surfaces at or near the same spot, descending and ascending nearly vertically like an elevator, and very rapidly as well (with the ascent being slower than the descent)