Order: Cetacea
Suborder: Mysticeti
Family: Balaenopteridae
Genus & Species: Megaptera novaeanglia(e) (prev. Megaptera nodosa)
APPEARANCE
The humpback whale is one of the best known of all the whales, due to interest in its photogenic above-water antics and its haunting form of communication. Humpback whales are so named do to the way their back arches forward when going from the surface to below the water. This species of whale is rather large, with the females being larger than the males. Females measure 45-50 ft (13.5-15 m) in length, whereas males attain lengths of only 40-48 ft (12-14.4 m). The southern herd of humpbacks are larger than the northern herd of humpbacks. This is also present in the herds of blue whales. On average, humpbacks weigh 25-40 tons (22 680-36 287 kg).
Humpback whales, unlike most other baleen whales, lack a streamlined body. Rather, their body is barrel-shaped and rounded, and narrows to a short peduncle (tail). The head is slim when seen from the side and rounded and broad when seen from above. Two blowholes are situated on the top of the head. These blowholes act as nostrils, and because they are constantly being filled with water must be cleared before the whale can effectively inhale. These great spouts of water often rise 10-13 ft (3-3.9 m) in the air. Humpbacks breathe 1-2 times per minute when at rest.
The top of the head and the skin covering the jaws are covered with bumps known as tubercles. Each tubercle usually contains two coarse hairs, the purpose of which are not known. Tubercles can also be found on the edge of the flippers and flukes.
Extending from the lower jaw to the navel are 20-35 ventral grooves known as pleats. Each pleat is roughly 8 inches (20 cm) apart. They expand when the mouth opens, allowing great volumes of water to be held in the oral groove. Their mouths lacks teeth, and instead have 330 pairs of large, fringed plates known as baleen or whalebone. The baleen are generally black but can be white, and measure at 2 ft (60 cm) in length.
Humpback whales have the longest flippers of any of the baleen whales, often measuring as long as 1/3 of the total body length. The dorsal fin, positioned 2/3 of the way back, is usually triangular and lacks the sickle-shape common to most rorquals (baleen whales with dorsal fins). The shape of the dorsal fin may vary, however. Scientists have found that the size and the shape of both the dorsal fin and the tail flukes are unique to each individual and can be used almost like fingerprints for identification. The tail flukes are notched and are up to 12 ft (3.6 m) wide.
Humpback whales vary greatly in colour. The back is usually black or slate grey, and the underside is generally light grey. However, the underside can be all white, mottled, or all black. The flippers are also generally dark on the top and light on the bottom, as are the tail flukes, but once again this can vary considerably.
Humpback whales have a life span of 50 years. They are most noted for their hauntingly beautiful songs, which consist of clicks and squeaks and are emitted only by the males while in the warmer waters. The sounds can reach levels of 40-50 kHz.
HABITAT
Humpback whales can be found in all of the world's oceans, but are usually found in 3 main herds: the North Pacific, North Atlantic, and Antarctic stocks. Humpbacks spend the summer months in the polar waters, and then follow specific migratory routes to the tropical waters to wait out the winter. The North Pacific herd, which can be found from Alaska to California in the summer, migrates south to the waters off Hawaii, Costa Rica, Mexico and Japan. The North Atlantic herd migrates from the coasts of Norway and Britain as well as Newfoundland and New Brunswick in Canada to West Africa and Central America. The Antarctic herd migrates the farthest: they swim 4000 miles (9000 km) to the Gulf of Panama.
Humpback whales prefer the coastal waters. They usually travel in large, loose groups.
Humpbacks are avid acrobats, often breaching and twirling in the air before smashing back down on the water. They may also skyhop, which involves sticking their head out of the water for 30 seconds, or lobtail, which involves slapping their tail on the water's surface.
Humpback whales swim 3-9 mph (6.75-20.25 km/h). They can dive to depths of 650 ft (195 m) for up to 30 minutes.
FOOD
Humpback whales eat a wide variety of food, from small crustaceans such as krill and copepods to plankton to small fish such as herring, capelin, mackerel and sand eel. They have two methods for hunting their prey. When lunge feeding, they open their mouths and swim through highly concentrated areas of food. When bubble-net feeding, a pod of humpbacks dive to depths of 50 ft (15 m) and form a large circle. They then rise at their prey while swimming in a spiral path, and blow a wall of bubbles which trap and confuse their prey. They then swim through the bubbles and feast.
Adult humpbacks do not feed during the winter, but instead rely on their blubber. When they do eat in the summer they use their fringed baleen to filter the food from the water.
ENEMIES
It is estimated that at one time as many as 150 000 humpbacks swam through the world's oceans. Due to heavy whaling, their numbers were cut drastically. A ban was placed on humpback whaling in 1966, and today their numbers have increased to approximately 10 000.
Humpbacks often fall victim to parasites that, although not killing the whale, may cause it some discomfort. At least three different species of barnacles and one species of whale lice can be found on the flippers and body of humpback whales.
Humpback whales may be attacked and killed by pods of killer whales, although this is rare and probably only occurs when the humpback is a juvenile or ill.
BREEDING
Humpbacks reach sexual maturity at 2-6 years of age. They breed during the late winter or early spring in the warm waters. To mate, the male and female rise to the surface and half-emerge from the water in a vertical position. They then embrace for 30 seconds, during which the female's eggs are fertilized.
The gestation period lasts for 11-12 months, after which one, rarely two, calves are born. The calf is 14 ft (4.3 m) long at birth. It is weaned for one year, and leaves its mother shortly thereafter. The mother will give birth to another calf every 2-3 years.
RELATIVES
The humpback is a rorqual along with the blue, minke, fin, sei and Bryde's whales.
RESOURCES CITED
1. "Humpback Whale" Funk & Wagnall's Wildlife Encyclopedia, vol 9, pg 1108-1109, 1974, NY, BPC Pub Ltd
2. "Humpback Whale" Wildlife Fact File, USA, IM Pub Inc
3. www.nwf.org/wildalive/whale/sciencefacts.html
4. www.zoomwhales.com/subjects/whales/species/Humpbackwhale.shtml
5. www.tmmc.org/humpback.htm
6. www.acsonline.org/factpack/humpback.htm
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