Whales, including the great whales, killer whales, dolphins, porpoises, beaked whales, river dolphins, etc., are airbreathing mammals, but over the past 50 to 60 million years have perfected the ability to live entirely in water. They belong to the order Cetacea, and are often referred to as cetaceans. Like the seals, they evolved from terrestrial carnivorous mammals, but the whales have taken their adaptations to living in a marine environment much further than have the seals. In cetaceans, the hind legs have completely degenerated; they have developed fluked tails for propulsion; the front limbs have been transformed into pectoral flippers; the nostrils have moved to the top of the head; they have lost their fur and instead utilize a thick layer of blubber with which to insulate themselves from the cold waters; the vertebrae have lost their interlocking processes because their tremendous mass is essentially weightless in the buoyancy of water and they do not need to support their weight on a rigid backbone (this has allowed the gigantism of many species). Because they must return to the surface every time they breathe, whales live in a vertical world, and unlike fish, their tails are flattened horizontally which better facilitates up and down movements. They have large lungs by comparison to most other mammals, and they have the ability to exchange up to 85% of the air in the lungs at each breath (compared with the 1520% exchange which occurs during normal breathing in humans). Most of the larger species produce a visible vaporous "blow" when they exhale at the surface. This blow forms mostly from condensation when the warm, moist air in the lungs is suddenly depressurized upon exhalation. The thick layer of blubber not only insulates them from the cold, it also aids in buoyancy because fat is lighter than water, and it is used as stored food energy during times of migration and fasting.
There are two basic types of whales…those which have teeth and those which are toothless. Whales with teeth belong to the suborder Odontoceti, and include sperm whales, killer whales and other dolphins, porpoises, beaked whales, narwhals, belugas, and others. These animals actively pursue motile and relatively large prey such as squid, fish, seals, and even other cetaceans. The toothed whales have developed very useful sonar (underwater echolocation) systems with which they can locate and capture prey, and avoid obstacles and predators, even while swimming in dark or turbid waters. The echolocation system works by focusing sound waves (produced in the nasal passages) through an oilfilled lens, or melon, which is set in a cradle on the front of the skull. The returned sound wave reflections are thought to be sensed primarily through the lower jaw and transmitted through fat to the ossicles of the inner ear. A rule of thumb is the larger the melon the better developed the sonar system, which implies more time spent in deep and/or turbid waters.
The toothless whales belong to the suborder Mysticeti, which includes all the filterfeeding species. These animals, including the right whales and rorqual whales, possess many rows of horny baleen, or whalebone, which hang down vertically from the roof of the mouth. The inside edge of each plate has a frayed appearance of dense bristles, and the plates overlap one another to the extent that the frayed edges form a very efficient sieve all around the edge of the mouth. As the whale moves through the water it opens its huge jaws and takes in a large quantity of water. The water is filtered through between the baleen plates thereby trapping any small prey animals, such as krill, tiny schooling fish, etc., inside the mouth. This food is then pushed back to the throat by the huge muscular tongue and swallowed. This process enables the baleen whales to take advantage of the almost limitless resource of krill and other secondary and tertiary levels of organisms near the base of the food chain. Different species of baleen whales have different sizes of baleen filter plates which allow them to coexist and yet feed on different prey. Baleen whales typically feed in the upper layers of water because the zooplankton and small schooling fish that make up most of their diet are dependent upon phytoplankton, which in turn is dependent upon sunlight. Therefore, they are not normally deep divers like some of the toothed whales, and seldom dive to more than 90 meters (300 feet) below the surface. Unlike the toothed whales, there is much less sexual dimorphism among the baleen whales, but in most species the females grow slightly larger than the males.
There are three species that are truly whales of the ice and remain year-round in Svalbard waters. The largest of these is the Bowhead whale which reaches lengths up to 20m and weighs close to 150 tons. Bowheads are filter-feeding baleen whales with rotund, black bodies, no dorsal fin and have white patches on the lower jaw and tail stock. Their massive triangle shaped head is the largest in the animal kingdom, being close to a third of the animal’s overall body length. They are the only baleen whale not to migrate to warmer waters to have their calves and spend their entire lives near or in the sea ice. During the winter they are found on the southern edges of the pack ice and may use their bowed jaw and large head to break through as much as half a meter of ice to open breathing holes. In the summer bowheads use ice leads to migrate further north to feeding grounds full of their main prey of copepods, amphipods, krill, and various other crustaceans. They swim slowly with their jaws open wide, skimming the surface, and may consume up to two tons of prey each day. Climate changes may affect prey availability and it is unknown how bowheads may be able to adapt to ice free Arctic conditions.
The other two Arctic whale residents are medium-sized toothed whales that are closely related, both of which are seen in the waters of Svalbard. The more common of these is the Beluga (the Russian word for white), which can reach a length of 4.6m (15 ft) and weigh almost 1,400 kg (3,000 lbs). The newborn of this species is light gray in color, but becomes completely white as it ages. The Beluga has a large, bulbous head, no dorsal fin and, unlike most whales, can nod and turn its heads. Belugas spend most of their lives in small, social groups and are known as the canaries of the sea because of their incredible whistles, chirps and squeaks. They are one of the most commonly seen cetaceans around Svalbard and in the summer feed in the fjords. Small groups slowly cruise along the edges of tidewater glaciers, most likely searching for prey. They have a diverse diet of squid, crabs, shrimps and several species of fish. Their main predators are killer whales, which hunt young calves in the summer. They are also taken by polar bears.
The other species, known as the Narwhal, is a grey, mottled animal that reaches three to five meters (10-16 ft) in length and is unique among cetaceans for having a long, straight, spiraled ivory tooth that grows to about two meters (six feet) in length directly in line with the body. This tusk is most commonly seen in males. Its function is unknown, but it is thought to be the basis for the unicorn legend. Narwhals travel in small groups. They tend to be in areas of high density pack ice and are more numerous in the Canadian Arctic. In Svalbard they are often seen in the north-west region and feed on fish species like Arctic cod, as well as squid and crustaceans. Narwhals are still hunted by natives in many parts of the Arctic including Greenland.
As should be expected, several other baleen whales, including the Blue, fin, Minke whales, and humpback whales are regularly sighted the Svalbard Archipelago, but only during the Summer season. These baleen whales are all closely related and are known as rorqual whales. They share the characteristic of having many throat grooves, which allow the throats to be expanded when feeding. Unlike the bowhead whale, rorquals engulf a single huge mouthful of water and then close their jaws and squeeze the water out through the short baleen plates. The advantage to this method is that when the throat area is constricted, they take on a surprisingly long and streamlined shape which allows some species to swim at speeds of 30 kph (19 knots). Most of the rorqual whales belong to the genus Balaenoptera, differing primarily in size and coloration. Even so, it takes a well-trained eye to identify them when they are encountered at sea. All the Arctic rorquals are widespread and are found in both Pacific and Atlantic sectors. These whales must migrate long distances between their low latitude Winter calving regions and the rich, high latitude Summer feeding areas, including the waters about Svalbard. Unlike the resident bowhead whale, these seasonal whales all have dorsal fins, which is a common trait to those cetaceans that do not spend much time among pack ice and ice debris.
Among the visiting toothed whales, the killer whale is probably the most easily recognized. It is essentially a huge dolphin, averaging about nine meters (30 feet) in length. The coloration is very striking with most of the body a glossy black, except for a highly contrasted bright white belly, a process on the flank, and a patch just behind the eye. This black and white counter-shading seems to be very common among marine predators. This species normally travels in pods made up of five to 20 individuals (usually consisting of an extended family). These groups are very cohesive and exhibit a high degree of cooperation in hunting prey and caring for one another. They are highly predaceous and feed on a large variety of prey including squid, sharks, rays, fish, sea birds, seals, and even other whales.
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