The Mysticetes family, filter feeders otherwise known as the baleen whales, include the largest species of whales and are sometimes referred to as the “great whales.” They can be found in all the world’s oceans. At times they will undertake extensive migrations. There are 3 families in this group.

Right Whales (Balaenidae)

Balaenidae The distinguishing features of Right whales are their highly arched upper jaw and their long narrow plates of baleen. Their heads are large when compared to total body length, and they have huge lower lips. They do not have a dorsal fin. The skin over their throats is smooth, and the neck vertebrae are fused.

Gray Whales (Eschrichtiidae)

Eschrichtiidae Like the Right whales, Gray whales also have no throat grooves, but there are two to four furrows present. Again they have no dorsal fin. Instead, there are several humps on the upper surface of the tail stock. The neck vertebrae of Gray whales is not fused together like that of the Right whales.

Rorquals (Balaenopteridae)

Balaenopteridae This group of whales have shorter and narrower baleen plates compared to the right whales. Their most distinguishing feature is the numerous throat grooves which extend from the chin to mid abdomen. Although a dorsal fin is present it is generally small. Like the Gray whales, Rorquals’ neck vertebrae are not fused. This family includes humpback whales: Megaptera novaeangliae. Humpbacks are well-known for their preference to migrate near coastlines and to breed close to tropical islands, and blue whales: Balaenoptera musculus Hunted virtually to extinction in the Southern Hemisphere, less than 2000 remain of the original 200,000 in Antartica in the early 1900’s.

What Is A Whale?

Whales are mammals. They are more closely related to humans than to the many fish and creatures which they share the oceans with. Like us, they are warm blooded, give birth to live young and they suckle their young. In their behaviour we see echoes of our own humanity.

Bones And Skin

Whales shape and size differ radically from land mammals. Much of this is due to the buoyant nature of water that has allowed them to attain enormous size.

Perfectly adapted for life in the oceans whales have radically changed their shape to one that is more efficient for moving through a denser medium such as water. They have become streamlined and the forelimbs have turned into rigid paddles (pectoral fins) which help with their balancing and steering. Whales have no hind limbs and, therefore, no hip or leg bones. The dorsal fins prevent whales from rolling. Part of their streamlining means that their skin is smooth and almost hairless, except for some hair around the mouth and chin, the external ear has been lost and the genitals and mammary glands are retracted within the body.

Although we may know the basics there is far less known about whale anatomy than any other group of mammals. This has partly been due to the difficulty of studying them in the wild making it impossible to understand the function of certain structures they possess.

Parasites

There are several creatures that attach to the skin of whales. They are referred to as parasites. However, they are not “true” parasites and gain no direct nourishment from the whale itself. Often the whale will provide scraps from their own meals that the parasite can feed on or it gives its guest a free ride to nutrient rich waters which are plentiful in food. The most noticeable of whales’ parasites are barnacles. These will usually form encrustations that occur under the chin and along the leading edge of the flippers. The change in temperature, when whales migrate from the cool Arctic and Antarctic waters to the warm tropics, will cause the barnacles to die and drop off. But they are quickly replaced again. All of the great whales have their own specialised barnacle population.

Another parasite associated with whales are “whale lice.” These are actually little crustaceans similar to crabs. They are usually found in the folds around the eyes, on flippers, throat grooves and around the barnacle infestations. They too do not damage the whale. They are unaffected by changes in temperature.

Temperature Control

How does a warm blooded mammal like us survive in an environment that can be extremely cold and cause them to rapidly lose body heat?

Temperature control provides a considerable challenge to the whale. Unlike land mammals, whales cannot use behavioural means, such as huddling together, to keep warm. That’s why they have developed blubber: a deep layer of fat under the whales’ skin that will not only store energy but act as an insulator. Blubber thickness varies between species but it has been measured at up to 50cm thick in Bowhead whales.

Blubber is great for keeping whales warm. But after prolonged activities, such as catching prey and swimming, whales could become extremely overheated. To prevent this whales have large arteries running through the blubber. The arteries pump blood to the outer skin where the surrounding water will cool it. When the whale has cooled down enough these same arteries will constrict and will not let as much blood flow through, allowing the blubber to become an insulator again.

The whales flippers, flukes and dorsal fins do not, however, have a layer of blubber. Therefore, whales have developed a temperature control system for these areas. This is known as counter current heat control and is also present in many land mammals including humans. The whale has modified it further.

The major arteries which supply the flipper, dorsal fin and tail are accompanied by two or more veins. Veins and arteries transfer heat between each other. As the blood flows to the extremities it is cooled so that no body heat will not be lost into the water, then as the blood flows back to the heart it will be reheated. Counter current heat exchange can also be used and controlled when the animal wants to cool off, allowing heat loss at the extremities.

Breathing/Respiration

For most people, their encounters with whales are not when they enter the oceans (the whales’ world) but rather when the whale momentarily enters their world in order to breathe. For, like us, whales have to breathe air. In whales, the nostrils have been modified into a blowhole on the top of the head. This forms a double blowhole in the baleen whales, which have two nostrils, and a single blowhole in the toothed whales. A series of valves and plugs closes the blowhole when the animal dives again.

It is during their short time at the surface that whales obtain all the oxygen they need for dives that can last up to two hours in some species. Although they breathe less often than land mammals, whales will compensate by taking deeper breaths and extracting more oxygen from the air they breathe. The whale will exchange a far greater volume of air from its lungs with each breath, 85-90%, almost completely exchanging the old air for new air unlike humans who only renew 10-20% of the air in the lungs. When a whale exhales, the air comes out of their blowholes between 300- 500 km per hour.

Whales do not have huge lungs. Proportionately, whales’ lungs are not significantly larger than land mammals. So to dive for minutes, maybe hours at a time, the whale has other adaptations, such as a modified circulatory system. They have a greater percentage of red blood cells. Red blood cells are responsible for transporting oxygen around the body. In addition, the heart rate of the animal will slow down when it is in a dive, the heart beating less times per minute. This condition is known as Bradycardia. Upon reaching the surface and breathing again, the heart rate rises sharply for a brief time. The length of time the whale is submerged will affect how high its heart rate rises when it breaths again. The blood circulatory system is modified as well. Blood flow becomes restricted when diving and it is only directed to the vital organs, almost stopping in other areas. However, whales can still remain very active because they are capable of storing large amounts of oxygen in their muscles before diving.

Diving And The Bends

All species of whales are remarkable divers, however, some are truly incredible, like the Sperm whale and Bottlenose whale who can stay submerged for up to 90 and 120 minutes. Not only that, but the Sperm whale dives down 2000m and possibly as deep as 3200m. The baleen whales will dive for about 40 minutes rarely longer, they are not as deeper divers (with the exception of the Grey whale which feeds by stirring up the bottom sediment and sieving out the small crustaceans, shellfish and worms) because their food source is more concentrated near the surface. Amongst the dolphins, the bottlenose will dive for about 15 minutes, the common dolphin will only dive for about 3 minutes.

When humans scuba dive, if they come to the surface too quickly, they can get a condition known as “the bends.” This can be fatal. Nitrogen gas in the air they are breathing dissolves into the bloodstream as they breathe at increasing depth and pressure. When coming back to the surface after a dive, the diver can get the bends if the nitrogen in the bloodstream comes out of liquid solution too quickly for the lungs to deal with it. It will then form small bubbles in the blood and tissue. This doesn’t happen to whales, why? The whale is a breath-hold diver, only taking down the air contained in its lungs and respiratory passages, so very little nitrogen will dissolve in their blood.

However, the whale still has to deal with immense changes in temperature and pressure. The routine dives made by Sperm whales takes them down as deep as 3000m to feed on giant squid. Therefore, if they are in tropical waters, the temperature will go from a warm 25oC in sunlight to total blackness and a temperature just above freezing point at depth. To deal with the great increase in pressure, the lungs of whales are elastic and are capable of collapsing without affecting the whale. This would be fatal in humans. When they do collapse, the air in them is forced into the nasal passages leading to the blowhole. The rest of the whale’s body adjusts to the increased pressure because a large proportion of the body is comprised of water, which is almost incompressible.

Echolocation

The evolution of land mammals saw the development of five main senses: sight; touch; taste; smell and hearing. These allowed them to receive clear and vital information through the air. When the ancestors of whales left the land to inhabit the oceans, their senses developed for air had to adapt and function underwater. Those senses which could not adapt, or were unnecessary, were lost, and in one case, an amazing new one developed.

This is what could be described as a sixth sense which is completely new, and can best be described as “seeing with ones ears.” This is exactly what the toothed whales are capable of doing.

When they returned to the marine environment, whales’ competitors, such as sharks, had already been evolving in the oceans for many millions of years. They had developed, and perfected, highly specialised senses such as smell and hearing. Whales were in competition with these sharks for food. They were also preyed upon by sharks. To compensate for this, whales had to develop quickly in a way that would let them compete successfully with the sharks. For the baleen whales, the problem was solved by living on small plankton that the sharks do not feed on. They also grew to enormous size, so the sharks could not attack them. But the toothed whales had a more interesting response to the problem when they developed echolocation.

Echolocation is used by whales to communicate, detect prey, navigate when sight isn’t adequate and get an acoustic picture of the underwater topography. When a whale echolocates, it emits sounds which radiate out from it. These sounds take the form of short broad-spectrum burst-pulses or clicks and are focused in a directional beam by the melon of oil in the whales head. The returning echoes from these sounds are received through the whales lower jaw and provide the whale with 3 dimensional information about their surrounding environment.

Information to date indicates that there are a series of events associated with a whale or dolphin’s echolocation pattern. When the animal is swimming along it will produce a general low frequency echolocation signal. This will provide it with information about the topography of the area such as water depth and the position of any coastal features or large animals in the area. If a new echo is received by the whale, it will want to collect more information about it, such as, is it predator or prey? To do this, the whale will produce a series of clicks with a broad frequency band. The echoes from these provide the whale with a series of bits of information. The higher the frequency of sound the more detailed the information is. The only draw back is that the whale needs to be close to the target when producing the high frequency sounds, or the echoes are quickly lost in the surrounding water. But once the whale or dolphin focuses on the target, its high frequency clicks will give a detailed picture of it. The details increase the closer the whale comes to the target and the clicks will be very close together and sound like a continuous “creaking.”

Not only is echolocation used to detect prey, it is believed that it can also be used to literally “stun” prey. Some species of whales no longer have functional teeth because they have developed echolocation to such an extent that they no longer need teeth. Sperm whales are a perfect example of this, they feed on the giant fast-swimming squid that are 12m long and longer. It is believed that they use intense sound to stun and disorient their prey. Their teeth in the lower jaw are much reduced in size and number. The same can be said of the Beaked whales, in this family the teeth of the female may never break through the gums, and in the males, often only two of the teeth will break through. Theories about these whales stunning their prey grew out of information from whaling times when large sperm whales were caught who had deformed or damaged jaws yet they had full stomachs and were very healthy.

Breeding And Reproduction

In order to streamline their bodies and allow ease of movement through water, the whales external genitalia had to be retracted into the body. Telling the difference between the sexes can at first appear quite difficult. But this is not the case and, in general, the technique for sexing whales is universal for all species. Basically, revealing a whale’s sex can be done by viewing the underbelly of the animal and noting the positioning of the slits, or genital opening, on the underside of the whale’s body. Although this is the most reliable and accurate way of sexing cetaceans, in some species there are other small differences among the sexes. For example, in most species of baleen whales, the females will tend to be about 10% larger than the males. However, this situation is reversed for the larger toothed whales, the males become the larger animals. For instance, Sperm whale females are 40% smaller than the males. These differences in size are not nearly as marked in the smaller whales such as dolphins and porpoises. Orcas have another characteristic which allows the sexes to be easily distinguishable. There is a difference in their dorsal fins. Male Orcas have long, straight, up and down dorsal fins that are somewhat larger than female Orcas’ which are quite curved.

To date, the majority of information about mating in whales has been gained by observing the dolphins and small whales which have been kept in captivity. Mating of whales in the wild has only been rarely observed. In migrating species, such as many of the baleen whales, breeding is seasonal, whereas in most of the other whale species it will occur throughout most, or all, of the year.

Being warm blooded mammals, whales give birth to live young. Gestation or pregnancy varies amongst whale species, but in general it takes approximately 10-12 months in baleen whales, and is timed to coincide with their annual migration patterns. They feed in the nutrient rich Arctic and Antarctic waters in the summer, moving to the tropical waters in the winter to breed and give birth. For the toothed whales gestation can be anywhere from nine months to 18 months. Twins are very rare. Usually a single young will be born fluke first rather than head first.

The calf is suckled by the mother close to the water’s surface so both of them can take time to breath. Feeding by the calf is different to that of land mammals. Because the mammary glands lie within the mother’s genital slit, the baby doesn’t actually latch on to a nipple. Instead strong muscles squirt the milk into the calf’s mouth. Whale milk is very concentrated with fat and protein and this enables the calf to grow very rapidly. Humpback whale calves will drink up to 600lt of milk a day from their mother.

The time a whale takes to suckle its young will also vary amongst species. In the rorquals of the baleen whales, lactation will last four to eleven months. After which the young calf is weaned and travels with other juveniles, leaving it’s mother. A year or more is the time taken by toothed whales for lactation. In fact, older female Pilot whales will lactate for longer than younger ones. In females less than 20 years old lactation will last for two to six years, but it can be up to 15 years in the older animals. This does not mean however, that the young whale will only feed on its mother’s milk for all that time. After approximately their first year of life, all young whales begin to take solid food.

those with teeth that actively hunt and catch their prey. And those with baleen that entrap their food. Baleen plates are essentially modified teeth, they form in the whales mouth a giant sieve used to strain their food out of the water.

In the oceans microscopic plants called phytoplankton use the energy from the sun to produce their own food. These plants are then eaten by zooplankton which are themselves microscopic animals: a large portion of which are crustaceans. They are related to crabs, lobsters, crayfish and shrimps. The word plankton refers to the fact that these animals are carried about by the water currents rather than their own swimming abilities. They are so small that swimming does not move them far, some plankton cannot swim at all. These creatures are at the base of the marine food chain and other animals in the oceans will feed of them.

The size of the baleen determines the size of the food the whale will eat. For example, Humpback whales have quite coarse baleen, therefore they feed on larger schooling crustaceans and fish, consuming up to 2 tone per day. Fin whales, by comparison, have much finer baleen and prey on smaller organisms such as plankton.

By developing baleen which enabled them to feed at the base of the food chain, the mysticetes are feeding at the most productive end and gain a lot of nourishment out of their food. This in turn is probably one of the reasons they were able to reach the enormous sizes they have attained today.

Feeding Methods

Even though the all mysticetes have baleen in common, their methods of feeding still vary among the different families. The Rorquals, to which the Blue, Fin, Bryde’s, Sei, Minke and Humpback whales belong, are “gulpers.” They have massive throat grooves which greatly expand as the animal takes a huge gulp of water and food. They then close their mouth and push up their tongue which expels the water out through the baleen and leaves all the food entrapped on the inside. The Right whales, and this includes the Bowhead, are “skimmers”. They have extremely long baleen (in the Bowhead whale it can be over 4m long). When feeding they plough through the water, allowing it to flow in through the front and out the baleen at the sides. This then traps the tiny animals on the baleen which they use their tongue to remove. The Grey whales are termed as “right-sided feeders”. They will swim to the bottom and stir up the sediment. They then suck the disturbed water into their mouths and sieve out any of the small bottom dwelling organisms that are in it. Because they use predominantly their right side to stir up the bottom, the baleen on this side can get quite worn down. They will also at times take mouthfuls of kelp and strain the small crustaceans off them.

The ondontocetes, the toothed whales, are not as large as their baleen relatives because they feed further up the food chain on fish and squid. They are active hunters in the ocean, using echolocation. This allows them to easily detect prey, and the intense sounds they produce are thought to actually stun and disorient their prey. The shape of the teeth does not allow them to chew their prey. They are adapted only to seize and hold it. The size and number of the teeth vary by species. Some, such as the Common dolphin, have over one hundred in each jaw. Others, such as the Sperm whale or Risso’s dolphin, do not have any in their upper jaws. Because they emerge from the gums several weeks after birth and remain for the animal’s entire life, the teeth have been used to find out whales’ ages.

Feeding Behaviours

Besides the physiological differences of feeding with baleen or teeth, certain species of whales have developed some very interesting and ingenious techniques to catch their prey.

One of the most intriguing of these techniques are the “bubblenets” used by Humpback whales in the northern hemisphere. When they come into contact with a large concentration of food the Humpback will move below the food and begin to circle it. As it then begins to move towards the surface, the whale will gently expel air from its blowhole. This air forms bubbles that rise in a circle around the food source. This forms a screen, or net, that will act as a barrier on the organisms, forcing them closer together and tightening their formation. The Humpback will then emerge vertically within the grouped animals, its mouth wide open, engulfing everything in its path. When making bubblenets, one whale might work alone or in cooperation with several others. The bubbles themselves can be as small as pearls or as big as basketballs.

A behaviour exhibited by Orcas is not as subtle as the Humpbacks’ bubblenets, but very spectacular. They will literally strand themselves in order to catch and eat fur seals from a sandy beach. The young Orcas learn how to do this by watching the older animals.

A behaviour similar to the Orca strandings has been exhibited in Bottlenose dolphins. They will herd schools of fish up onto a mud bank. Then they will intentionally strand themselves to feed on the trapped fish, before sliding back into the water. This behaviour has been used by fishermen in West Africa. They will beat sticks against the water to attract schools of dolphins who drive the fish up the shore. The fishermen entrap the fish in gill nets and the dolphins take their share before swimming away.