Humpback Whale, perhaps the best known of the baleen whales, occurring in all
oceans. Humpback whales migrate to the pack ice in summer and to shallow,
tropical breeding areas in winter. The northern and southern hemisphere forms
are distinctly different. Humpback whales have a dorsal fin about two-thirds of
the way from the front of the body and a characteristic high humping or arching
of the back when diving. They have long, thin pectoral fins and a massive tail,
the underside of which is mottled white and black and can vary distinctly in
shading pattern. Because humpback whales usually throw their tails above water
just before a deep dive, researchers have used the distinctive tail coloration
and the shape of the trailing edge of the tail to identify several thousand
individuals.
Humpback whales feed on invertebrates and fish. During a feeding lunge
through clouds or schools of prey, the whale's throat expands tremendously. This
expansion is aided by throat pleats, or folds, which open up, accordionlike, to
as far back as the navel. The whale closes its mouth around tons of water and
prey and then pushes the water out through about 300 baleen plates that hang
from the upper jaw and act as a sieve. Humpbacks may feed in social groups of up
to 22 whales, all lunging at the same time. Individuals or small groups may
sometimes corral prey with their tails and long flippers or by blowing bubbles
around schools of prey to form bubble walls.
Humpback whales are highly acrobatic. They often slap their flippers and
tails on the water's surface and breach, or leap out of the water. An adult
humpback whale may leap completely clear of the water, then fall back in a
cascade of foam. Such aerial activity occurs at all times of year but is
especially prevalent in the winter mating and calving grounds. Males, females,
and even young calves may engage in such displays.
During the winter breeding season, male humpback whales compete for mates in
any of several different ways. Young, sexually mature males keep their distance
from one another and sing long, complicated songs in apparent vocal competition
for access to females in estrus. A male will sometimes escort a female and her
calf, if she has one, for a period of hours or days, avoiding or battling any
other males that attempt to swim close to the female. Boisterous, surface-active
groups of males may battle each other, bloodying their heads as they ram and
rake one another, in apparent competition for one or more females in the group.
Mating results in a single young born 11 to 12 months later. The calf is nursed
for less than one year.
Humpback whales were hunted most intensively in the early 1900s, when the
worldwide population was reduced to less than 10 percent of its original size.
Some populations appear to have increased since protection of humpback whales
began in 1944. The humpback whale is classified as an endangered species.
Scientific classification: The humpback whale belongs to the family
Balaenopteridae of the suborder Mysticeti, order Cetacea. It is classified as
Megaptera novaeangliae.
Contributed By:
Bernd G. Wursig
Humpback Whale Microsoft® Encarta® Encyclopedia 2001. © 1993-2000
Microsoft Corporation. All rights reserved.
