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Humpback Whale (Megaptera novaeangliae)

Humpback Whale (Megaptera novaeangliae)

All text on this page is copyright protected: © 2014 Kelvin Aitken.
All rights reserved. Students may use this information for personal research only. Not for commercial use.

Order: Cetacea
Family: Balaenopteridae
Genus: Megaptera
Species: novaeangliae
Taxonomic name: Megaptera novaeangliae

Humpback whales belong to the Rorqual family of cetaceans.

Female humpback whales grow to 19 meters and males to 17.5 meters.

There are two basic populations of humpback whales; the southern and northern. Southern humpback whales have, on average, much more white colouration on the belly extending onto the flanks while northern humpback whales have only a small area of white on the belly, sometimes being completely black or dark grey. That said some individuals may depart from this norm with some southern members mostly or totally black on the belly. Their seasonal migration separates the northern and southern stocks though there may be some temporary intermingling of individuals whose late departure may cross over with the early arrival of individuals from the corresponding hemisphere.

Humpback Whales are distinctive in that they have the largest appendages of any living animal, namely their knobbly pectoral fins which are close to 1/3 of their total length. These pectoral fins may be completely white or only white, or partly white, on the underside. The leading edge of these fins are crenelated with a series of bumps and knobs, often with encrusting barnacles. The pectoral fins are used for a variety of purposes including banking, breaking, propulsion (though only slightly as the bulk of their movement is controlled by the tail flukes), defence and as flails during mating behaviour.

The upper surface of the head forward of the blowhole is covered in a collection of protruding knobs which are also present under the tip of the lower jaw. This latter small patch of chin knobs are often covered in barnacles and are used on occasion to inflict scratches on the sensitive skin of other whales during courting or social interaction. There are two visible blowholes that are slightly raised above the contour of the head which deliver a tall bushy blow. Some individuals have been seen to control the muscles of the blowhole to deliver horizontal spouts perpendicular to the bodies axis. The body is either dark grey to black with some having a light grey mottling. The back of a Humpback Whale (Megaptera novaeangliae) often has bumps and always shows pits and scars, similar to the appearance of old acne marks, or fresh marks from cookie cutter sharks.

The tail is broad and often raised above the surface at the end of the diving sequence. This behaviour is called fluking and allows each animal to be individually recognised by the unique “fingerprint” of crenelated indentations on the rear edge, and colour pattern on the underside, of the flukes. These tattered patterns are present on each animal when born and are added to depending on the individuals encounters with ice, other humpbacks or orcas which bite at the tail flukes.

Females migrate to the tropics to take advantage of the warmer waters to give birth to their calves which do not have the blubber reserves of an adult to survive the polar winters. Calves are born, after a 12 month gestation period, at 4.5-5 meters long and feed on very rich milk which the female ejects from her mammary glands situated behind and below her pectoral fins. The calf will continue to feed from its mother for 8-9 months after which it is weaned. Mature females give birth every two or more years though some may give birth for some successive years. Male humpbacks follow the female migration to the tropics to mate and engage in boisterous social behaviour with fellow males and young sub-adults of both sexes.

Humpbacks feed on a variety of krill (small shrimp-like animals), plankton and small schooling fish. Their method of feeding employs their pleated throat which expands greatly, like that of a croaking frog, as they gulp in vast mixtures of water and prey. The whale then closes its mouth and, using its huge tongue, pushes the mixture through the curtains of baleen, surrounding the internal edges of its mouth, and out through its lips. When this sieving process is completed the whale swallows the remaining mass of food. This rich diet allows the feeding whale to store energy in the form of blubber which is a thick, fibrous insulating layer of fat and oil. Blubber is used as insulation in the cold polar feeding grounds and also serves as an efficient energy reserve for their extensive summer migration during which they fast.

One notable method of feeding is when a pod of humpbacks form a circular net of bubbles to herd and condense schools of small fish. The net is constructed when one or more whales swims in a circular pattern slowly exhaling bubbles. When the upper bubbles reach the surface the whole pod launches vertically up through the compacted school with their mouths wide open, bursting through the surface in a spectacular group display. While feeding occurs in the rich polar waters during the summer months they have also been seen to feed on rare occasions in their tropical breeding areas or during their migration.

Humpback Whales are a favourite with whale watch tours due to their wide distribution and spectacular surface activity. This includes tail slapping, pectoral fin slapping and breaching, the most spectacular form of behaviour where the whale launches itself either partially or fully above the surface in a display of awesome power and grace.

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