Humpback Whale, Megaptera novaeangliae, Gallery One

Humpback Whales Gallery One

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Humpback Whales
Gallery Two

About Humpback Whales

The humpback whale, Megaptera novaeangliae, is one of the best known and certainly one of the most familiar of the large whales. Its aerial acrobatics and its ethereal whale song make it a popular choice for whale watching. Once hunted to near extinction, there are now an estimated 80,000 humpback whales in the world.
The humpback whale is a baleen whale feeding mostly on krill or small fish. During the summer they live in polar waters after which they migrate large distances to their winter breeding grounds in tropical waters. Over the winter they live on their fat reserves built up during summer months in the polar waters.

Name

The humpback whale derives its name from the characteristic hump seen when the whale is diving. Although other whales arch their back when diving, such as the Sperm Whale, the dorsal fin lies on a thick layer of blubber and this exaggerates the humpback's hump.
The Scientific name: Megaptera novaeangliae, derives from the greek Mega (huge) and ptera (wing) owing to their unusually large pectoral fins (up to 6m long). Finally, Novaeangliae meaning New England, comes from the location whalers originally found them in abundance.
The Gaelic name Míol mór dronnach derives from Míol mór (Whale), and dronnach meaning hunched.

Description

Humpback whales are baleen whales, meaning they sieve small organisms through a plates of baleen in their mouths. Baleen plates look like a very course hair structures organised into a comb like sieve that hangs from the upper jaw. This contrasts with the tooted whales, like the sperm whale, that catch and eat fish in a similar fashion to other toothed animals.

Baleen whales are usually bigger than toothed whales and the humpback is no exception, measuring on average 16 meters in length and weighing 35 to 40 tons. This is approximately the same length as a double decker bus or larger. A typical adult male is 11-17 metres and the females are usually slightly larger at 11-19 meters. The largest specimen recorded was 19 metres. A typical calf measures about 4 or 5 meters in length.

The most striking characteristic of the humpback are its pectoral pins. At up to 6 metres long, these are the largest pectoral fins of any cetacean. The leading edge of the pectorial fin is lined with tubercules (round nodules) which are actually hair folicles. See insert image. These tubercles increase the humpback whale's aerodynamic efficiency adding to whales agility. A Canadian company has recently desiged a wind-turbine blade inspired by the humpback whale's flipper, (To learn more, see this website )

Life Expectancy and Reproduction

The humpback whales's life expectancy is very similar to our own, with whales living from 45 to 70 years of age and females outliving the males. Females breed from about about 5 or 6 and although males probably mature at or just after this age, it is unlikely that they breed before 10 years of age. Females will breed every two to three years and in rare circumstances will breed in consecutive years. Gestation takes 11½ months and calves are born after the winter migration back to the warmer equatorial waters.

Courtship takes place after the whales return to their winter feeding grounds, which are located nearer to the equator. The courtship is a boisterous, energetic and promiscuous (which may involve several partners) affair involving a long pursuit of the female. Males pursue the female in competitive groups who battle and fight in an effort to pursue and impress the female. The group of pursuing males can grow to over 20 animals then one by one they drop off. Pursuits can go on for days. Didier Noirot filmed some extraordinary footage of the event for the BBC Blue Planet series. If you haven't seen this, It is online on the BBC website, Here and Here.

Social Groups

The social groups are typically very small, usually from two to five. This is probably optimised for their lightly distributed food source. However, where large shoals of herring gather (Norway and Alaska), larger groups come together in two ways. Firstly, many separate groups, typically of 3 or 4 whales, converge on the same breeding grounds but operate separately. Secondly, and more interestly from a behavioural point of view, groups of up to 12 whales, usually female, come together to cooperatively feed using a technique known as bubble feeding. In this technique, one ot two whales dive below the fish then coral them by releasing short blasts of bubbles in a small circle or spiral. This keeps the fish in a tightly bound shoal for the other members of the pod to lunge into and scoup the bounty.

Vocalisations

The humpback whale is known for its vocalisations and song. Although the vocalisations are made by male and female, it is the male that sings the complex songs that they are famous for. Cetaceans have no vocal cords so the different frequencies of their song are produced by the nasal cavity. The humpback's song is usually heard at the breeding grounds and so it is thought that the song plays a part to impress the female, and also as a warning to other males. The high frequency song can be heard up to 20km away, however low frequency vocalisations can be heard up to 150km away suggesting that there may be other reasons for these vocalisations, such as keeping groups connected during migration.