Humpback Whales
The Humpback Whale, when fully grown, grows to be about 40-50 ft. in length and can weigh up to 79,000 lbs. Humpback Whales have an unusual, but very recognisable body shape. They are known for being an acrobatic in the water when the breach and slap the water.
Males produce a complex whale song, which lasts for 10 to 20 minutes and is repeated for hours at a time. The purpose of the song is not yet clear, although it appears to have a role in mating. Found in oceans and seas around the world, Humpback Whales typically migrate up to 25,000 kilometres each year.
Humpbacks feed only in summer, in polar waters, and migrate to tropical or sub-tropical waters to breed and give birth in the winter. During the winter, Humpbacks fast and live off their fat reserves. The species’ diet consists mostly of krill and small fish. Humpbacks have a diverse repertoire of feeding methods, including the spectacular bubble net fishing technique.
Humpback Whales can easily be identified by their stocky bodies with obvious humps and black dorsal colouring. The head and lower jaw are covered with knobs called tubercles, which are actually hair follicles and are characteristic of the species. The tail flukes, which are lifted high in the dive sequence, have wavy rear edges.
The long black and white tail fin, which can be up to a third of body length, and the pectoral fins have unique patterns, which enable individual whales to be recognised. Several suggestions have been made to explain the evolution of the Humpback’s pectoral fins, which are proportionally the longest fins of any cetacean. The two most enduring hypotheses are the higher maneuverability afforded by long fins, or that the increased surface area is useful for temperature control when migrating between warm and cold climates.
The tail of each Humpback Whale is unique.Humpbacks have 270 to 400 darkly coloured baleen plates on each side of the mouth. Ventral grooves run from the lower jaw to the umbilicus about halfway along the bottom of the whale. These grooves are less numerous (usually 16–20) and consequently more prominent than in other rorquals. The stubby dorsal fin is visible soon after the blow when the whale surfaces, but has disappeared by the time the flukes emerge. Humpbacks have a distinctive 3 m (10 ft) bushy blow.
Calves are about 13–15 ft. long when born and weigh approximately 1500 lbs. They are nursed by their mothers for their first six months, then are sustained through a mixture of nursing and independent feeding for a further six months. Calves leave their mothers at the start of their second year, when they are typically 30 ft. long. Both sexes reach sexual maturity at the age of five with full adult size being achieved a little later.
Females have a lobe about 6 in. in diameter in their genital region. This allows males and females to be distinguished if the underside of the whale can be seen, even though the male’s penis usually remains unseen in the genital slit. Male whales have distinctive scarring patterns and pigmentations on their underside, some resulting from high speed courtship chases of females. Females typically breed every two or three years. The gestation period is 11 months, yet some individuals can breed in two consecutive years. Humpback Whales can live for 40–50 years.