Humpback Whale - Megaptera novaeanglia
Desricption:
Humpback Whale, perhaps the best-known of the baleen whales. It occurs in all oceans, as it migrates to the pack ice in summer and to usually island breeding areas in winter: there are distinct northern and southern hemisphere forms. Humpback whales have long thin flippers and a variably white underside of the massive tail. Since humpback whales usually throw the tail above water just before a deep dive, researchers have used the distinctiveness of tail coloration and trailing edge tail shape to identify several thousand whales by their tails. Humpback whales have a dorsal fin about two-thirds from the front of the body and a characteristic high humping or arching of the back when diving.Humpback whales feed on invertebrates and fish by lunging rapidly through clouds of prey. They close their mouths around tons of water and prey and then push the water out through about 300 baleen plates that hang from the top jaw and serve as a sieve. The throat expands tremendously during a feeding lunge, and this expansion is aided by throat pleats or folds which open up, accordion-like, to as far back as the navel, near midbody. Humpbacks also feed in social groups of up to 22 whales all lunging at the same time.
They blow underwater bubbles around schools of prey to form bubble walls, and flick or corral prey with their long flippers and with their tail. They are also very aerially acrobatic, with individuals flipper and tail slapping at the surface and breaching or leaping out of the water. It is a magnificent sight to watch a 15 m (50 ft) adult humpback whale leap totally clear of the water and fall back in a cascade of foam.
Aerial activity occurs at all times of year but is especially prevalent on the winter mating and calving grounds. Males, females, and even that year's young can be aerially active.
Humpback whales appear to have several different mating strategies. One is where males space each other out and sing long complicated songs in apparent vocal competition for access to females in oestrus. Another strategy appears to be when a male "escorts" a female (often with a calf) for hours or days, avoiding or battling any other males that attempt to swim close to the female.
A third strategy consists of very boisterous surface-active groups of males battling each other, after bloodying their heads as they ram and rake each other, in apparent competition for one or more females in the group. Mating begets a single young 11 to 12 months later; it is nursed for less than one year.
Environment:
It occurs in all oceans, as it migrates to the pack ice in summer and to usually island breeding areas in winter: there are distinct northern and southern hemisphere forms.Food:
The whale feeds on planktonic crustaceans and small fish.Problem:
Humpback whales were not extensively hunted in the 19th century, but were decimated in the first part of the 20th century by whaling.Solution:
Populations appear to be increasing in numbers since protection in 1944.
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