Humpback Whale

From Wikipedia, the free encyclopedia

Humpback Whale
Size comparison against an average human
Conservation status
Vulnerable (IUCN) [1]
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Subclass: Eutheria Order: Cetacea Suborder: Mysticeti Family: Balaenoptiidae Genus: Megaptera Gray, 1846 Species: M. novaeangliae
Binomial name
Megaptera novaeangliae (Borowski, 1781)
Humpback Whale range

The Humpback Whale, Megaptera novaeangliae, is a marine mammal which belongs to the baleen whale suborder. The Humpback is one of the larger species of whale: an adult can usually range between 12–16 metres (40–50 ft) long and weighs approximately 36,000 kg (79,000 lb); females, on average, are larger than males. It is well known for its breaching (leaping out of the water), its unusually long front fins, and its complex whale song.

The Humpback Whale lives in oceans and seas around the world, spending the summer months feeding in polar waters before migrating to warmer waters to breed in the winter. It is regularly sought out by whale-watchers on various parts of the coastline of Australia and the United States. An albino Humpback Whale has been seen on the Australian east coast and another Humpback, Humphrey, became famous when he was twice rescued near San Francisco. Like other large whales, the Humpback has been a target for the whaling industry and it is estimated that its population was reduced by up to 90% due to hunting that continued until a moratorium was introduced in 1966.

Contents 1 Taxonomy 2 Description and behaviour 2.1 Social structure and courtship 2.1.1 Markings 2.2 Feeding 2.3 Vocalizations 3 Population and distribution 4 Whaling 5 Threats other than hunting 6 Whale-watching 6.1 Famous humpbacks 6.1.1 Migaloo 6.1.2 Humphrey 7 In popular culture 8 Media 9 Footnotes 10 References 10.1 Books 10.2 Journal articles 11 External links

[edit] Taxonomy

The Humpback Whale was first identified as "baleine de la Nouvelle Angleteer" by Mathurin Jacques Brisson in his Regnum Animale of 1756. In 1781, Georg Borowski described the species, converting Brisson's name to its Latin equivalent, Baleana novaeangliae. Early in the 19th century Lacépède shifted the Humpback from the Balaenidae family, renaming it Balaenoptera jubartes. In 1846, John Edward Gray created the genus Megaptera, classifying the Humpback as Megaptera longpinna, but in 1932, Remington Kellogg reverted the species names to use Borowski's novaeangliae.^[2] The common name is derived from their humping motion while swimming. The generic name Megaptera from the Greek mega-/μεγα- "giant" and ptera/πτερα "wing",^[3] refers to their large front flippers. The specific name means "New Englander" and was probably given by Brisson due the regular sightings of Humbacks off the coast of New England.^[2]

Humpback Whales are rorquals (family Balaenopteridae), a family that includes the Blue Whale, the Fin Whale, the Bryde's Whale, the Sei Whale and the Minke Whale. The rorquals are believed to have diverged from the other families of the suborder Mysticeti as long ago as the middle Miocene.^[4] However, it is not known when the members of these families diverged from each other.

Though clearly related to the giant whales of the genus Balaenoptera, the Humpback has been the sole member of its own genus since Gray's work in 1846. More recently, DNA sequencing analysis indicates the Humpback and the Gray Whale are close relatives of the Blue Whale, the world's largest animal; should further research corroborate these relationships, it will be necessary to reclassify the rorquals.

[edit] Description and behaviour

Humpback Whales can easily be identified by their stocky bodies with obvious humps and black dorsal colouring. The head and lower jaw are covered with knobs called tubercles, which are actually hair follicles and are characteristic of the species. The tail flukes, which are lifted high in the dive sequence, have wavy rear edges.

The long black and white tail fin, which can be up to a third of body length, and the pectoral fins have unique patterns, which enable individual whales to be recognised, in a similar way to the bill markings on Bewick's Swans. Several suggestions have been made to explain the evolution of the Humpback's pectoral fins, which are proportionally the longest fins of any cetacean. The two most enduring hypotheses are that the higher maneuverability afforded by long fins is a significant evolutionary advantage, or that the increased surface is useful for temperature control when migrating between warm and cold climates.

Humpbacks have 270 to 400 darkly coloured baleen plates on each side of the mouth. Ventral grooves run from the lower jaw to the umbilicus about halfway along the bottom of the whale. These grooves are less numerous (usually 16–20) and consequently more prominent than in other rorquals. The stubby dorsal fin is visible soon after the blow when the whale surfaces, but has disappeared by the time the flukes emerge. It has a distinctive 3 m (10 ft) bushy blow.

Calves are about 4–4.5 m (13–15 ft) long when born and weigh approximately 700 kg (1500 lb). They are nursed by their mothers for their first six months, then are sustained through a mixture of nursing and independent feeding for a further six months. Calves leave their mothers at the start of their second year, when they are typically 9 m (30 ft) long. Both sexes reach sexual maturity at the age of five with full adult size being achieved a little later. Fully grown the males average 15–16 m (49–52 ft), the females being slightly larger at 16–17 m (52–56 ft), with a weight of 40,000 kg (or 44 tons); the largest recorded specimen was 19 m (62 ft) long and had pectoral fins measuring 6 m (20 ft) each.^[5]

Females have a lobe about 15 centimetres (6 in) in diameter in their genital region. This allows males and females to be distinguished if the underside of the whale can be seen, even though the male's penis usually remains unseen in the genital slit. Females typically breed every two or three years. The gestation period is eleven months, yet some individuals can breed in two consecutive years. Humpback Whales can live for 40–50 years.

[edit] Social structure and courtship

The Humpback social structure is loose-knit. Usually, individuals live alone or in small transient groups that assemble and break up over the course of a few hours. Groups may stay together a little longer in summer in order to forage and feed cooperatively. Longer-term relationships between pairs or small groups, lasting months or even years, have been observed, but are rare. The range of the Humpback overlaps considerably with many other whale and dolphin species — but whilst it may be seen near other species (for instance, the Minke Whale), it rarely interacts socially with them.

Courtship rituals take place during the winter months, when the whales migrate towards the equator from their summer feeding grounds closer to the poles. Humpback Whales do not feed while in their wintering waters. Competition for a mate is usually fierce, and female whales as well as mother-calf dyads are frequently trailed by unrelated male whales dubbed escorts by researcher Louis Herman. Groups of two to twenty males typically gather around a single female and exhibit a variety of behaviours in order to establish dominance in what is known as a competitive pod. The displays last several hours, the group size may ebb and flow as unsuccessful males retreat and others arrive to try their luck. Techniques used include breaching, spy-hopping, lob-tailing, tail-slapping, flipper-slapping, charging and parrying (see whale behaviour for a detailed description of these techniques).

Whale song is assumed to have an important role in mate selection; however, scientists remain unsure whether the song is used between males in order to establish identity and dominance, between a male and a female as a mating call, or a mixture of the two. All these vocal and physical techniques have also been observed while not in the presence of potential mates. This indicates that they are probably important as a more general communication tool.

[edit] Markings

The male whales have distinctive scarring patterns and pigmentations on their underside, some resulting from the high speed chases of the females they participate in during mating. The female humpbacks seem to show little interest in the males many times, according to the limited observations thus far.

Scientists realised that the varying patterns on the Humpback's tail fluke were sufficient to identify an individual. Such unique identification is not possible in other whale species (except some groupings of Orcas, notably in the Pacific Northwest), so the Humpback has become one of the most-studied species. A study using data from 1973 to 1998 on whales in the North Atlantic gave researchers detailed information on gestation times, growth rates, and calving periods — as well as allowing more accurate population predictions by simulating the mark-release-recapture technique. A photographic catalogue of all known whales in the North Atlantic was developed over this period and is today maintained by Wheelock College.^[6] Similar photographic identification projects have subsequently begun in the North Pacific, specifically by SPLASH (Structure of Populations, Levels of Abundance and Status of Humpbacks), as well as in other areas around the world.

[edit] Feeding

The species feeds only in summer and lives off fat reserves during winter. It is an energetic feeder, taking krill and small schooling fish, such as herring, capelin and sand lance. It will hunt fish by direct attack or by stunning them by hitting the water with its flippers or flukes.

Its most inventive feeding technique is known as bubble net fishing. A group of whales will blow bubbles while swimming to create a visual barrier against fish, while one or more whales in the group make vocalizations that drive the fish against the wall. The bubble wall is then closed, encircling the fish, which are confined in an ever-tighter area. The whales then suddenly swim upwards and through the bubble net, mouths agape, swallowing thousands of fish in one gulp. This technique can involve a ring of bubbles up to 30 m (100 ft) in diameter and the cooperation of a dozen animals at once. It is one of the more spectacular acts of collaboration among marine mammals.

Humpback Whales are preyed upon by Orcas. The result of these attacks is generally nothing more serious than some scarring of the skin. However, it is likely that young calves are sometimes killed. Sometimes a group of whales will rush to the aid of a threatened fellow, and fend off the Orca's attack, in another example of cooperation.

[edit] Vocalizations

Main article: Whale song

Although much was known about the Humpback Whale due to information obtained through whaling, the migratory patterns and social interactions of the species were not well known until two separate studies by R. Chittleborough and W. H. Dawbin in the 1960s. Roger Payne and Scott McVey made further studies of the species in 1971.

Their analysis of whale song led to worldwide media interest in the species, and left an impression in the public mind that whales were a highly intelligent cetacean species, a contributing factor to the anti-whaling stance of many countries. Some scientists have hypothesized that the song may serve an echolocative function.^[7]

As cetaceans have no vocal chords, whales generate their songs by forcing air through their massive nasal cavities. Humpbacks repeat patterns of several sounds in a low register that vary in amplitude and frequency in consistent patterns over a period of hours or even days. Scientists are still unsure of the purpose of whale song, and it remains largely a mystery. Only male Humpbacks sing, so it was initially assumed that the songs were solely for courting. The primary purpose of whale songs is no longer thought to be to attract females, although it may sometimes be involved in the mating process. It is likely that whale songs serve a variety of purposes, as the whales sing on many occasions and throughout the year. The most interaction among the singing whales, with the limited observations thus far, has been seen amongst males: they sometimes head towards a singing male, and although at times they will pass by, sometimes the two swim together. Aggression has not been observed, and no one knows exactly what is being communicated. A whale's unique song evolves slowly over a period of years —never returning to the same sequence of notes. Every year the song is different with new aspects, yet there are great similarities between the songs of the whales that inhabit the same area in the oceans, to a point where only experts are able to distinguish individuals by their songs. During the feeding season, Humpback Whales make altogether different vocalizations, which they use to scare fish into their bubble nets. There are ongoing studies to attempt to determine how these large-brained animals are using their other vocalizations and their songs.^[8]

[edit] Population and distribution

The Humpback Whale is found in all the major oceans, in a wide band running from the Antarctic ice edge to 65° N latitude. It is a migratory species, spending its summers in cooler, high-latitude waters, but mating and calving in tropical and sub-tropical waters. Annual migrations of up to 25,000 kilometres (16,000 statute miles) are typical, making it one of the farthest-travelled of any mammalian species. An exception to this rule is a population in the Arabian Sea, which remains in these tropical waters year-round. The species is not found in the eastern Mediterranean, the Baltic Sea or the Arctic Ocean.

Internationally this species is considered vulnerable. Specific countries are creating action plans to protect the Humpback; for example in the UK the Humpback Whale has been designated as a priority species under the national Biodiversity Action Plan, generating a specific set of actions to conserve this species. Since the moratorium on hunting, the species has revived somewhat from their state of near-extinction.

[edit] Whaling

Main article: Whaling

The first recorded Humpback kill was made in 1608 off Nantucket. Opportunistic killing of the species is likely to have occurred long before, and it continued with increasing pace in the following centuries. By the eighteenth century, the commercial value of Humpback Whales had been realized, and they became a common target for whalers for many years.

By the 19th century, many nations (and the United States in particular), were hunting the animal heavily in the Atlantic Ocean — and to a lesser extent in the Indian and Pacific Oceans. However, it was the introduction of the explosive harpoon in the late 19th century that allowed whalers to accelerate their take. This, coupled with the opening-up of the Antarctic seas in 1904, led to a sharp decline in all whale populations.

It is estimated that during the 20th century at least 200,000 Humpbacks were taken, reducing the global population by over 90%. To prevent species extinction, a general moratorium on the hunting of Humpbacks was introduced in 1966 and is still in force today. In his book Humpback Whales (1996), Phil Clapham, a scientist at the Smithsonian Institute, says "this wanton destruction of some of the earth's most magnificent creatures [is] one of the greatest of our many environmental crimes".

By the time the International Whaling Commission (IWC) members agreed on a moratorium on Humpback hunting in 1966, the whales had become sufficiently scarce as not to be worthwhile hunting commercially. At this time, 250,000 were recorded killed. However, the true toll is likely to be significantly higher. It is now known that the Soviet Union was deliberately under-recording its kills; the total Soviet Humpback kill was reported at 2,710 whereas the true number is now believed to be 48,000.

As of 2004, hunting of Humpback Whales is restricted to a few animals each year off the Caribbean island Bequia in the nation of St. Vincent and the Grenadines. The take is not believed to threaten the local population.

Starting in 2007 Japan is planning to kill 50 Humpback Whales per year under its JARPA-II research program.

[edit] Threats other than hunting

Over 300,000 whales, porpoises, and dolphins are killed every year in fishing net entanglements. The Humpback Whale suffers this plight as well. [National Geographic, Jan. 2007] The stranding of fourteen Humpbacks off the coast of Cape Cod, Massachusetts in 1987 was one of the events, along with the Exxon Valdez oil spill, that led the United States to develop a legal framework and procedures for dealing with MMUMEs (Marine Mammal Unusual Mortality Events). The United Kingdom also has programmes to investigate events of the large scale death of marine mammals, such as the 1988 epizootic that killed 18,000 common seals.

In the 19th century, two Humpback Whales were found dead near sites of repeated oceanic sub-bottom blasting, they had mechanical damage to the ears, including ruptures, ossicular chain disruption, tissue dissection, bloody effusions, and fractures.^[9]

The ingestion of saxitoxin, a PSP (paralytic shellfish poison) from contaminated mackerel has been implicated in Humpback Whale deaths.^[10]

The protozoan ciliate Haematophagus megapterae, attaches to the baleen plates of the Humpback as it does to the Fin Whale and Blue Whale, yet is apparently not pathogenic, and merely feeds off the whales' red blood cells.

[edit] Whale-watching

See also: Whale-watching

Humpback Whales are generally curious about objects in their environment. They will often approach and circle boats. Whilst this inquisitiveness was akin to suicide when the vessel was a whaling ship, it has become an attraction of whale-watching tourism in many locations around the world since the 1990s.

Whale-watching locations include the Atlantic coast off the Samana province of the Dominican Republic, the Pacific coast off Oregon, Washington, Vancouver, Hawaii and Alaska, the Bay of Biscay to the west of France, Byron Bay north of Sydney, Hervey Bay north of Brisbane, the coasts of New England and Newfoundland, New Zealand, the Tongan islands, the northern St. Lawrence River and the Snaefellsnes peninsula in the west of Iceland. The species is popular because it breaches regularly and spectacularly, and displays a range of other social behaviours.

As with other cetacean species, however, a mother whale will generally be extremely protective of her infant, and will seek to place herself between any boat and the calf before moving quickly away from the vessel. Whale-watching tour operators are asked to avoid stressing the mother unduly.

[edit] Famous humpbacks

[edit] Migaloo

An albino Humpback Whale that travels up and down the east coast of Australia has become famous in the local media, on account of its extremely rare all-white appearance. The whale, born in 1990, is called Migaloo (a word for "white fellow" from one of the languages of the Indigenous Australians). Speculation about the whale's gender was resolved in June 2004, when it found a mate for the first time, and proven to be male. Because of the intense interest, environmentalists feared that the whale was becoming distressed by the number of boats following it each day. In response, the Queensland government ordered the maintenance of a 500 m (1,600 ft) exclusion zone around the whale. Recent close up pictures have shown Migaloo to have skin cancer and/or skin cysts as a result of his lack of protection from the sun.^[11]

[edit] Humphrey

Main article: Humphrey the whale

The most famous Humpback Whale is Humphrey the whale, who was rescued twice by The Marine Mammal Center and other concerned groups.^[12][13] The first rescue was in 1985, when he swam into San Francisco Bay and then up the Sacramento River.^[14] Five years later, Humphrey returned and became stuck on a mudflat in San Francisco Bay immediately north of Sierra Point below the view of onlookers from the upper floors of the Dakin Building. He was pulled off the mudflat with a large cargo net and the help of a Coast Guard boat. Both times he was successfully guided back to the Pacific Ocean using a "sound net" in which people in a flotilla of boats made unpleasant noises behind the whale by banging on steel pipes, a Japanese fishing technique known as "oikami." At the same time, the attractive sounds of Humpback Whales preparing to feed were broadcast from a boat headed towards the open ocean.^[15] Since leaving the San Francisco Bay in 1990 Humphrey has been seen only once, at the Farallon Islands in 1991.

[edit] In popular culture

In Moby-Dick, a novel where the chief whale protagonist is a Sperm Whale, Herman Melville describes the Humpback Whale as "the most gamesome and light-hearted of all the whales, making more gay foam and white water than any other of them".

Humpback Whales were a plot element in the film Star Trek IV: The Voyage Home. In the film, an alien probe arrives at 23rd century Earth and attempts to contact the by then extinct whales. The crew of the Enterprise travel back in time to obtain a breeding pair of Humpbacks to communicate with the probe and forestall the Earth's destruction. In Disney's Fantasia 2000, a segment featuring a pod of frolicking Humpback Whales in the air and within icebergs is set to Ottorino Respighi's Pines of Rome, and in Disney/Pixar's Finding Nemo, a Humpback Whale guides Marlin and Dory to Sydney, Australia.

Judy Collins' 1970 album Whales and Nightingales featured a recording of the traditional song "Farewell To Tarwathie", on which Collins sang to the accompaniment of a recording of a Humpback Whale.

A breaching Humpback Whale serves as the logo for the Pacific Life insurance company.

[edit] Media

See also: List of whale songs

[edit] Footnotes

[edit] References

[edit] Books

[edit] Journal articles

[edit] External links

Some of the following documents are in PDF format:

• ARKive - images and movies of the humpback whale (Megaptera novaeangliae).
• Public Domain Photos of Humpback Whales - SeaRealm
• Photos and information about humpback whales and other cetaceans in Mayumba National Park, which sees up to 10% of the world's humpback whales breeding in its waters each year from July to October.
• 70South - information on the Humpback Whale
• A detailed analysis of the form and function of the humpback whale song, from the University at Buffalo
• In-depth discussion of selected Humpback Whale vocalizations, an interview with Sean Hanser, on The Inoculated Mind.
• Estimating the humpback population in the Pacific, from the National Oceanic and Atmospheric Administration
• Estimating the humpback population in the Atlantic, from Dalhousie University
• Attempts to estimate whale populations in the Arabian Sea, from the International Whaling Commission
• PBS Nature: Humpback Whales
• Glacier Bay documentary has footage of bubble net feeding, and Deep Blue:Kingdom of the Sun has footage ot courtship leaps from Tonga.
• Homepage for The Oceania Project. Humpback Research, Hervey Bay, Queensland, Australia
• The Dolphin Institute Whale Resource Guide and scientific publications
• The Whalesong Project
• Ryuji Suzuki on the complex syntax of whalesong phrases
• Humpback Whale Gallery (Silverbanks)
• Krill and Humpbacks — BBC nature documentary maker David Attenborough in a video from YouTube's BBCWorldwide channel
• Images and Movies of Whales and Dolphins. Text is in French