Bowhead Whales: Fascinating and Vocal Mammals of the Arctic
An Impressive Marine Mammal
In the cold water of the Arctic, an animal with a huge, bow-shaped mouth feeds and sings. The animal is known as the bowhead whale. It lives for over a hundred years, produces beautiful songs, and can break through sea ice a foot deep. It also has the largest mouth of any animal in the world.
The bowhead whale can reach a length of over sixty feet and weighs an estimated seventy-five to a hundred tons. Despite its size, the whale feeds on tiny organisms known as plankton, which it filters out of the water with the baleen in its mouth.
Bowhead whales usually travel on their own, apart from a mother and her calf, but they are occasionally seen in groups. They are very vocal animals at certain times of the year. Like humpback whales, they produce complex sound patterns known as songs. These songs are diverse and very intriguing.
Bowhead Whale Classification
Order Cetacea (whales and dolphins)
Suborder Mysticeti (baleen whales)
Habitat and Distribution
The scientific name of the bowhead whale is Balaena mysticetus. It used to be known as the Greenland whale or the Greenland right whale. It's thought that "right" whales were given their name because they were the right whales to hunt.
Bowhead whales spend a lot of time under the Arctic ice, making them difficult to study. In the winter, they live at the southern extent of the ice. In summer, they move into channels between ice floes and visit bays and estuaries.
The animals live in five different subpopulations, three in the North Atlantic and two in the North Pacific. Recent research suggests that these subpopulations may not be as distinct as was once thought. There seem to be overlaps between some of the groups.
The five subpopulations and the location where they're found are listed below.
- Spitsbergen in Norway
- Baffin Bay-Davis Strait between Greenland and Canada
- Hudson Bay-Foxe Basin in Canada
- Bearing-Chukchi-Beaufort Sea between Alaska and Russia
- Sea of Okhotsk in Russia
An adult bowhead whale has a rotund body. The animal is black except for a white patch at the front of its lower jaw. This patch may be broken up by small black spots that often look like beads on a necklace. Some individuals have a white or grey band in front of their tail flukes.
The huge head of the whale makes up about one third of its body length. Its curved mouth has the shape of a bow. Although its head and mouth are large, the whale has small eyes. Its two nostrils or blowholes are located on a raised area on its back. This area is known as a stack. The blowholes produce a v-shaped blow.
There is no dorsal fin on the animal's back, which allows the whale to swim right underneath the ice. The raised stack enables the whale to breathe through a small hole in the ice. It either creates this hole with its strong, reinforced skull or uses a breathing hole that's already been created. The animal's skin often bears scars produced from encounters with ice.
What Is Baleen?
Baleen whales have no teeth. Their baleen consists of a series of plates that hang from the upper gumline in a direction that is perpendicular to the direction of water flow into the mouth. The plates are arranged in two groups, one on either side of the mouth. In a bowhead whale, there are about 330 plates in each group. The plates in a group are parallel to each other and are only about a centimetre apart.
Each baleen plate is triangular in shape. It's made of a protein called keratin, which also makes up our fingernails and hair. The outer edge of a plate is smooth, but the inner edge has a frayed or fringed appearance. The fibres in the fringes are often referred to as bristles. The bristles of a baleen plate form a tangle with the bristles of other plates. As a result, a hairy mat is produced. This mat traps plankton.
A person looking at a whale's baleen from the side may see a neat, orderly arrangement of plates that looks rather like a giant comb (assuming the whale's mouth is partially open). This is shown in the video below. If the person is lucky enough to view the open mouth from the front, they may be able to see the long tangles of bristles on the inner edges of the baleen plates.
The colour of the baleen, size of the plates, and texture and length of the bristles is different in different whales. Bowhead whales have very long bristles.
Bowhead whales have the longest baleen of all the mysticete whales with a maximum length of 13.1 feet (4 meters).— NOAA Fisheries
The video below shows a right whale skim feeding. (The video contains no sound.) Bowhead whales also skim feed.
How Does a Baleen Whale Feed?
A bowhead whale seems to be mainly a skim feeder, although it may feed underwater as well. During skim feeding, the whale swims at the surface of the water with its mouth open, as in the video above. This allows sea water to enter the mouth. Tiny creatures collectively known as plankton are trapped on the baleen and become the whale's food. The sea water leaves through the sides of the animal's mouth.
A whale licks the trapped food off its baleen with its tongue. According to the American Cetacean Society, the tongue of a bowhead whale weighs about one ton, or 907 kg. It's a powerful structure. The manipulation of the baleen with the tongue breaks it down. In fact, the action of the tongue creates the frayed inner edge on a baleen plate as it erodes the plate. Like our fingernails and hair, the baleen of a whale never stops growing, although it may slow down as the whale ages. This allows the damaged baleen to be replaced.
It might seem that the bowhead whale's method of catching tiny organisms must be a very inefficient way of feeding. It's obviously effective, though. Baleen whales reach huge sizes. The blue whale is a member of the baleen whale group and feeds on plankton. It's not only the largest whale in existence but is also the largest animal on Earth.
What Does a Bowhead Whale Eat?
Plankton is a collection of tiny or microscopic organisms that either drift in the ocean without swimming or swim so weakly that they are unable to resist water currents. Bacteria, diatoms, microscopic algae, very small jellyfish, eggs, larvae, and tiny crustaceans are all part of the plankton.
The most important component of the plankton for bowhead whales is the crustaceans. These animals include euphausiids, which resemble small shrimp. Krill are members of the order Euphausiacea and are very common in plankton. They are generally less than an inch in length, although some giant species are a few inches long. Copepods are also important crustaceans in the whale's diet. They are classified in several different orders.
Bowhead whales are usually solitary animals. They are occasionally seen in small groups of two to three animals. Rarely, they are seen in larger groups. The large gatherings tend to develop during the annual migration in the spring. This is also the time when whale songs have been recorded.
Members of the general public may know about the haunting songs of humpback whales. Researchers have discovered that bowhead whales also produce beautiful songs. In early 2015, scientists reported that they had recorded twelve new songs sung by thirty-two bowhead whales during their spring migration northwards. The whales belonged to the Bearing-Chukchi-Beaufort subpopulation. Previously, researchers had discovered sixty-six different songs sung by bowhead whales, although these recordings were recorded over a longer period of a year.
The 2015 discovery is significant not only because it may tell us more about socialization and communication in bowhead whales but also because it's unusual. Humpback, blue, and sperm whales also sing, but the bowhead whale has a much greater diversity of songs than these whales.
Bowhead whales are unique among all other whales in that they change their songs within and between years.— Kate Stafford, University of Washington
The video below includes the sounds of bowhead whales and other marine mammals in the Arctic.
Why Do Whales Sing?
Researchers aren't sure why whales sing. Only male humpback whales produce songs. Scientists theorize that at least in this species the purpose of the songs is to attract females. Other theories have been suggested, however. The songs may provide long-distance contact between the whales and maintain group cohesiveness. They may warn of a problem or of danger. They may even be used to advertise the identity of a particular whale or their group.
Unlike toothed whales, baleen whales are unable to echolocate. During echolocation, a whale (or dolphin) emits high-pitched sounds that bounce off objects and reflect back to the whale. The reflected sound gives the whale an impressive amount of information about an object, including size, shape, density, position, distance, and speed of movement.
It's been suggested that baleen whale songs help with navigation and environmental analysis and partially replace echolocation, One theory says that baleen whales compare distant and distorted songs to the correct version of the song stored in their memory. This may tell them not only where the singers are located but also something about the environment between them and the singers.
The idea that whales sing for enjoyment has also been raised, but this suggestion isn't being considered seriously because it can't be tested.
Reproduction and Lifespan
Bowhead whales mate in the late winter or spring. They don't breed every year, however. The female generally has only one calf and gives birth every three to seven years. The gestation period is thirteen to fourteen months. The baby is grey in colour at birth.
Researchers estimate the age of bowhead whales by determining the age of stone or ivory harpoons embedded in dead whales and by an examination of eye tissue. They say that a lifespan of longer than 100 years is likely. Some researchers even suggest that a lifespan of 200 years is possible.
There is increasingly good evidence that bowhead whales can live for well over 100 years, and they may be the longest-lived mammal on Earth.— The American Cetacean Society
The literature states that the bowhead whale population is both of least concern and endangered. This sounds impossible, but the assessments actually refer to different subpopulations of the whale. According to the IUCN, or the International Union for Conservation of Nature, the Bearing-Chukchi-Beaufort Sea population is of least concern, the Sea of Okhotsk population is endangered, and the Spitsbergen population is critically endangered.
Commercial whaling took a tremendous toll on the bowhead whale population. Today the whales are no longer hunted commercially. They are actually increasing in number in the Bearing-Chukchi-Beaufort Sea region. Subsistence hunting by indigenous people in the whale's habitat is allowed, but a quota must be followed. This low-level hunting doesn't seem to be interfering with the recovery of the population.
It's hard to get accurate population counts because of the secretive life of the whale, but it seems that it isn't recovering in all parts of its range. Overall, though, it's doing okay because of the success of the Bearing-Chukchi-Beaufort Sea population. Some researchers have expressed concern about the effects of gas and oil exploration, entanglement in fishing gear, ship strikes, pollution, disturbance by tourists, and the loss of Arctic ice. The loss of ice may be biggest threat of all for Arctic mammals.
Some More Bowhead Whale Facts
- Bowhead whale dives usually last up to sixteen minutes. Dives slightly over thirty minutes have been recorded, however.
- The whales swim slowly at two to six miles an hour, but they can swim up to thirteen miles an hour for a short period of time during an emergency.
- The animals have thick blubber in order to insulate them from the cold. Blubber is fat, but compared to the fat of land animals it's thicker and contains more blood vessels.
- The blubber of a bowhead whale may be as thick as 1.6 feet. It provides protective padding and buoyancy as well as insulation. It can also be used as a source of energy.
- Like other whales, bowhead whales slap their tail flukes on the surface of the water, breach, and spy-hop. In breaching, a whale jumps completely or partially out of the water and then lands on its side with a large splash. In spy-hopping, a whale rises part way out of the water in a vertical position as though it's looking at its surroundings.
Bowhead whales are very interesting animals. They may well have a rich repertoire of behaviour that we haven't yet discovered. Learning more about the whale in its natural habitat without interfering with its life will be a challenge, but the effort should be very worthwhile.
© 2015 Linda Crampton