Part 3

The decline in the number of teeth in the sperm and bottlenose whales is thought to be the elimination of structures which are no longer useful. Whereas a porpoise's long mouth, bristling with sharp teeth, insures the hooking and retention of a slippery active fish, a small mouth with a few teeth is adequate to crush and slurp down the squid and the weak-swimming fishes of the abyssal depths.

The sperm whale is the largest of the squid feeders, reaching 60 feet. There is a diminutive counterpart, the pygmy sperm whale, which reaches 13 feet. It is exceedingly rare, whereas the sperm whale is abundant in temperate and tropical seas. The beaked whales complete the groups specialized for feeding on squid. Besides the modification of the mouth, all these whales are noted for their ability to dive to great depths where their food abounds. Not only can they dive to great depths, but they can stay submerged for long periods--up to an hour? Sperm whales have been found entangled in the submarine cables which were known to be on the bottom at a depth of 3,000 feet. It is clear that such feeding habits have opened up vast areas of the oceans to these species.

Filter Whales

The whalebone whales seem to have undertaken two different lines of specialization in feeding: The right whales developed an enormous head with a very large filter plate, whereas the rorquals are much more streamlined with a small filter plate. The ability of the latter to gather food is insured by the pleated throat. The right whales lack a dorsal fin and are decidedly less streamlined. The rorquals have a dorsal fin. There are two species which do not exactly fit in either group. The humpback whale appears to be like the rorquals in that it has a pleated throat and a suggestion of a fin. It is however, a very bulky slow swimming species. The California gray whale, apparently, is intermediate between the two groups and may be thought to be a survivor of the ancestral stock from which both groups differentiated. It has neither a pleated throat nor a fin. The gray whale, like the right whale, has been slow to recover from whaling. It is likely that the populations were never very large. Only the rorquals seem to have the numbers needed for large whaling operations.

Significance of Blubber

Heat Conservation

As whales extended their operations into the icy waters of polar regions or into the cold waters of the ocean depths, they had to develop means of keeping warm. Anyone who has attempted to swim in cold water knows how quickly one loses his body heat and becomes chilled. Whales minimize the heat loss by accumulating a thick layer of fat just below the surface of the skin. The fatty layer, called blubber, not only keeps the whale warm, but it also provides for food storage. It has already been stressed how important it is for whales to survive long periods without eating, so it is likely that the two specializations arose together.

There are, however, extensive areas of the whale which cannot be blanketed with fat and these are the flippers and the large tail flukes. It has been observed that the blood going into these structures gives up its heat not to the outside but to the veins which parallel and surround the arteries. By this anatomical feature most of the heat which would otherwise be lost to the water, is recaptured by the veins which deliver the heat back into the body. Of course, this means that the tissues of the tail flukes and flippers function at temperatures much lower than those found within the body. Here we find that nature was using the principal of the heat exchanger long before man discovered it or put it to work in air conditioning.

Whales are so well insulated that they stay quite warm 24-36 hours after death. Whalers must process the whales quickly, for otherwise, at the elevated body temperature, decomposition proceeds most rapidly and ruins much of the meat. It is possible that the baleen-bearing whales do not cross the warm equatorial waters because they overheat. No one has yet determined whether the newborn young have a sufficient layer of fat to protect them from the cold water, and it has been suggested that whales calve in temperate waters to prevent the babies from being chilled. However, there are species like the narwhal and the white whale which calve in Arctic waters.

Buoyancy

Another aspect to the extensive deposits of fat is that these tissues are lighter than water and help counteract the heaviness of the whale's body so that with the assistance of the lungs neutral buoyancy is achieved. The fat is accumulated in between the muscle strands, and in fact, in every available nook and cranny.

Food Storage

Much of this fat is drawn upon for food. Whenever a whale is existing on its fatty tissue, acetone is one of the waste products which must be eliminated in the breath. This pungent material makes the breath very strong and noticeable at these times. Certainly among whales, there is no stigma attached to being fat or having halitosis.

Ordinarily fatty tissues only accumulate when there is a surplus of food over the needs of the animal. You might suspect that whales would need to stockpile fat first, in order to remain warm and buoyant, and that growth would be curtailed and accomplished last. However, studies on the growth of whales show that the efficiency of food gathering is so high and food so plentiful, that growth not only continues but at a tremendous pace.

Sexual Maturity

Whales mature sexually between their third and seventh years. Toothed cetaceans attain sexual maturity later than filter-feeding whales. A blue whale is sexually mature at 5 years, whereas porpoises require at least 7 years. Most filtering whales are sexually mature in 2 or 3 years. Whales are not fully grown at sexual maturity, but they continue to grow for years. In most mammals growth stops with sexual maturity. Female whales generally can be expected to produce a baby every other year, for the gestation period is approximately one year. Babies are nursed for about 9 months. At birth the baby is completely formed and active, but lacking baleen, must nurse. A blue whale baby at birth weighs approximately 8 tons, about 1/12th of the weight of the mother. The mother provides the baby with 50 gallons of milk a day. Since the nursing is done under water, and the baby must surface frequently to breathe, the act of nursing is very brief. Muscles in the breasts of the mother force the milk into the baby's mouth in large amounts. The baby will double its length in 7 months, which averages to a daily weight gain of 220 pounds. During all this time the mother must fatten for the winter ahead, and perhaps continue to grow herself.

Life Span

It is not known for certain how long a whale may live after completing its growth. At the present time, commercially important species seldom attain physical maturity before being captured. Many whales which are captured are measured for scientific study. Such measurements also keep the whalers from taking undersized juveniles. Whales apparently do not live to be very old. Fifty years appears to be the best current estimate of a life span.

Whale Intelligence

Whales are apparently very intelligent animals. Whalers have remarked how difficult it is to approach whales which have previously escaped. The gray whales were observed actually avoiding the coast after shore whaling had been carried out for a few seasons. Animal trainers have found the toothed whales particularly apt pupils, and these animals are the stellar attraction of the various oceanaria.

Whale Senses

Sight

Little is known, however, about the capabilities of the various sensory organs. Certainly the eyes are very important and are effective under water. It is not likely that the eye is very effective out of water, even though whales do elevate the head out of the water for a look around. The behavior has been appropriately called "spyhopping," and it is manifested usually in the ice floes. Killer whales are believed to search the sea's surface and the edge of the icebergs for seals and birds.

Hearing

Whales appear to have very acute hearing. The report of a whaling gun will alarm whales which have previously tolerated the whaling vessel close aboard. Whalers have noted that in very foggy weather whales are much more difficult to approach because of the increased sensitivity to noise. The toothed cetaceans which are gregarious are capable of a great variety of vocalizations. Much of this is ultrasonic to man and it has been suggested that these emissions are used like man's sonar for finding obstacles and food. Considering the limited range of vision possible in water which is usually hazy or turbid, such a feature would be most useful. There is a continual chatter among members of a porpoise school, or gam, as the whalers call them. The accumulated noise serves as a beacon to which straying members can home when they have gotten out of visual range, which incidentally is under 300 feet. No one yet knows exactly how these animals can produce these sounds without being able to move air across the vocal chords. They do not exhale under water, and yet they are continually noisy.

Smell

The sense of smell is not important to whales, and the organ was abandoned when the nostrils were shifted to the back of the head and modified for diving. Although man may never be able to test whales experimentally for their sensual acuities, it is quite apparent that they are fully aware of their environment. They clearly recognize the environmental signposts which guide them to and from their various areas. Oceanographers are not nearly as adept in knowing where they are on the ocean. Whales clearly recognize their own particular kind, and they do not intermingle. Incidentally, man finds it difficult to differentiate some of the whale species. Because of the rarity of specimens and information, the identity of some species may still be in doubt.

Habits