Classification
Humpback Whale, perhaps the best known of the baleen whales belongs
to the family Balaenopteridae of the suborder Mysticeti, order Cetacea.
They are classified as Megaptera novaeangliae.
Distribution
Humpback Whales occur in all oceans. They migrate to the pack ice in
summer and to shallow, tropical breeding areas in winter. The northern
and Southern Hemisphere’s forms are distinctly different.
Appearance
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.
Diet
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.
Behavior
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.
Breeding
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
calf born 11 to 12 months later. The calf is nursed for less than one year.
Impact
Humpback whales often cooperate to feed on a large school of fish, driving
it into a tight formation before all breaking through the surface together
with their mouths wide open.
