The humpback whale can be distinguished by its large size, knobbly head and 5m long flippers. Individuals found in the Atlantic Ocean have mainly white flippers, but those found in the Pacific Ocean have a darker colouration on the upper surface of their flippers. Humpbacks in the southern hemisphere are generally more lightly coloured on the flanks. The bumps found on the head are called tubercles, and each one contains a single hair follicle, which may be used in a sensory capacity, much like a cat's whiskers. The flukes are distinctive compared with any other whale species; the black and white markings and scalloped edges are as unique as a human fingerprint, allowing experts to name thousands of individuals around the world. The wavy edged flukes are raised during dives, enabling researchers to keep track of individual whales from year to year.
The humpback whale is renowned for being one of the most energetic of the large whales with its spectacular breaching, lobtailing and flipper-slapping. Its scientific name Megaptera novaeangliae means 'big winged New Englander' because of its long flippers that look like wings when it breaches and because it was first described in New England. The species' worldwide popularity on whale watch tours has helped to ensure that they are the focus of many conservation efforts. These measures have an umbrella effect and protect not only humpbacks but also many other species found in their protected areas, including species that experience the same risks.
Male humpbacks sing the longest, most complex songs in the animal kingdom. Songs consist of a complex series of whistles, squeals and deep sonorous calls divided into 'verses' and sung in a specific order, which may last for as long as half an hour. Males in the same area of the breeding grounds sing the same songs, which change gradually over time. Humpback whales have unusual feeding behaviour - they sometimes herd their prey or create a kind of fishing net by exhaling air in a spiral of bubbles. Fish cluster tightly inside these 'bubble nets' allowing the whale to swim through with its mouth open and eat them. Humpbacks are capable of travelling at 25 km/h or more, however during migration they move more slowly, resting and socialising along the way. Humpback whales make long journeys. Each population of humpbacks has its own migration route; generally they spend the winter in warm, low latitudes or tropical waters breeding and giving birth, and the spring, summer and autumn feeding in cooler, high latitude polar waters. The humpbacks which feed in Antarctic waters and travel north to breed off Colombia and Panama make the longest confirmed migration of any mammal.
More than 100,000 humpbacks were killed for their oil in the past yet they are currently recovering in many places and were recently reclassified as Least Concern (IUCN 2008), although certain populations retain an IUCN Endangered status. There is also concern about the apparently discrete, small populations of humpback whales in various oceans for which status information is lacking. The main humpback populations are found in the North Atlantic, the North Pacific and the Indian Ocean and there is some mixing between different populations. Threats to humpback whale numbers worldwide include: habitat loss; chemical and noise pollution; entanglement in fishing nets and lack of food.