The Humpback Whale (Megaptera novaeangliae) is one of the larger rorqual species. Adults range in length from 12 – 19 metres (40 – 70 feet) and weigh approximately 36,000 kilograms (79,000 pounds). The Humpback Whale is the easiest baleen whale to identify, with a broad rounded head covered with tubercles or knobs.
The knobs that are along each edge of the jaws show protruding hairs that are very distinctive. The body of the Humpback Whale is blackish with white throat grooves. It has a bulky body construction which narrows noticeably at the tail area. Perhaps the easiest way to identify them is by looking at their flippers, which are very large (up to 5 metres long) mottled black on top and white underneath and very scalloped on the trailing edge. The dorsal fin appears as a hump at the moment when the whale dives.
The Humpback Whale is an acrobatic animal, often breaching and slapping 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.
Humpback Whales 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 metres (10 feet) bushy blow.
Female Humpback Whales typically breed every two or three years. Their gestation period is 11.5 months, yet some individuals can breed in two consecutive years. Humpback Whales were thought to live 50 – 60 years.
Newborn Humpback calves are roughly the length of their mothers head. A 50 foot mother would have a 20 foot newborn weighing in at 2 tons. They are nursed by their mothers for approximately six months, then are sustained through a mixture of nursing and independent feeding for possibly six months more.
Female Humpback Whales reach sexual maturity at the age of five with full adult size being achieved a little later. According to new research, males reach sexual maturity at approximately 7 years of age. Fully grown, the males average 15 – 16 metres (49 – 52 feet), the females being slightly larger at 16 – 17 metres (52 – 56 feet), with a weight of 40,000 kilograms (or 44 tons). The largest recorded Humpback was 19 metres (62 feet) long and had pectoral fins measuring 6 metres (20 feet) each. The largest Humpback on record, according to whaling records, was killed in the Caribbean. She was 88 feet long, weighing nearly 90 tons.
The Humpback Whale social structure is quite flexible. Usually, individuals live alone or in small groups that assemble and break up over the course of a few hours. Groups may stay together a little longer in summer in order to forage and feed together. Longer-term relationships between pairs or small groups, lasting months or even years, have been observed, but are rare.
Found in oceans and seas around the world, Humpback Whales typically migrate up to 25,000 kilometres each year.
Humpback Whales feed only in summer, in polar waters and migrate to tropical or sub-tropical waters to breed and give birth in the winter. They go to the Galapagos as an extension trip, humpbacks go to give birth on the coastal waters of mainland Ecuador and every year dozens of them return there. Some individuals arrive to the archipelago, but they are rather occasional visitors. During the winter, Humpbacks fast and live off their fat reserves. Their diet consists mostly of krill and small fish.
Both male and female Humpback Whales can produce sounds, however only the males produce the long, loud, complex ‘songs’ for which the species is famous. Each song consists of several sounds in a low register (range of a note) that vary in amplitude (measure of a wave) and frequency, and typically lasts from 10 to 20 minutes. Songs may be repeated continuously for several hours. Humpback Whales have been observed to sing continuously for more than 24 hours at a time. As cetaceans have no vocal chords, whales generate their song by forcing air through their massive nasal cavities.
Humpback whales are conservative whales and will not approach boats, although they do not mind if a boat approaches them.
Humpback whales are considered vulnerable. Most monitored stocks of Humpback Whales have rebounded well since the end of the commercial whaling era. However, the species is considered endangered in some countries where local populations have recovered slowly, including the United States.