Humpback Whale

## Description

The Humpback whale (Megaptera novaeangliae) is a species of baleen whale. It is a rorqual; a member of the family Balaenopteridae. The Humpback whale is known for breaching and other distinctive surface behaviors, making it popular with whale watchers. Found in oceans and seas around the world, these mysterious giants typically migrate up to 16,000 km (9,900 mi) each year. They feed in polar waters and migrate to tropical or subtropical waters to breed and give birth. Like other large whales, the Humpback whale was a target for the whaling industry and humans once hunted the species to the brink of extinction.

## Appearance

Humpback whales are bulky and have thin rostrums and proportionally long flippers, each around one-third of its body length. They have a short dorsal fin that varies from nearly non-existent to somewhat long and curved. As a rorqual, Humpback whales have grooves between the tip of the lower jaw and the navel. They are relatively few in number in this species, ranging from 14-35. The mouth is lined with baleen plates, which number 270-400 for both sides. Unique among large whales, Humpback whales have bumps or tubercles on the head and front edge of the flippers; their tail flukes have jagged trailing edges. The tubercles on the head are 5-10 cm (2-3.9 in) thick at the base and poke up to 6.5 cm (2.6 in). They are mostly hollow in the center, often containing at least one fragile hair that erupts 1-3 cm (0.4-1.2 in) from the skin and is 0.1 mm (0.0039 in) thick. The tubercles develop early in the womb and may have a sensory function as they are rich in nerves. The dorsal or upper side of Humpback whales is generally black; the ventral or underside has various levels of black and white coloration. Whales in the southern hemisphere tend to have more white pigmentation. The flippers can vary from all-white to white only on the undersurface. The varying color patterns and scars on the tail flukes distinguish individual animals.

## Distribution

Humpback whales inhabit all major oceans from sub-polar latitudes to the equator. There are four global populations of Humpbacks and they do not interact with each other: North Pacific, Atlantic, Southern Ocean, and Indian Ocean populations. Humpbacks live at the ocean's surface, both in shallow coastline waters and the open ocean. They migrate seasonally from the warm tropical waters where breeding and calving take place, to feeding areas in Arctic waters.

## Behavior

Typically, Humpback whales live alone or in small loose groups that can disband after a few hours. Groups may stay together longer in summer to forage and feed cooperatively. Longer-term relationships between pairs or small groups, lasting months or even years, have rarely been observed. Humpbacks sing more loudly than most other whales. Its songs can be heard over distances of several miles. The songs are sung by adult males, last up to 20 minutes, and then are repeated. Every year all the male whales sing the same song. While a whale sings, it floats in the water, its head down, and it is relatively motionless. The whale’s song purpose is not clear, though it may have a role in mating. Humpbacks make long journeys. During migration they travel slowly, socializing and resting along the way. Each humpback population has its own migratory route. They usually spend winter in warm, low-latitude, or tropical waters mating and giving birth, and during the rest of the year, they feed in cooler, higher-latitude polar waters.

## Diet

Humpback whales are carnivores (piscivores, planktivores) and eat krill and small fish from schools such as haddock, herring, capelin, salmon, sand lance, pollock, and mackerel. They feed mostly during summer, living off their fat during winter.

## Reproduction

Humpbacks are polygynous, and the males compete aggressively for mating access to females. They breed during winter in tropical waters. After a gestation of 11.5 months, one calf is born. Females must feed their calves around 45 kg of milk every day for 5-7 months until weaning, and calves may remain with their mothers for as much as a year. Mothers are affectionate and protective towards their calves, swimming nearby and often touching their babies with their flippers. Male humpbacks do not give parental support to calves. Mating usually takes place once every two years, though sometimes it occurs twice within three years. These whales are reproductively mature when they are 4-5 years old, and the birthing interval is 2 years.

## Population

### Population threats

Humpbacks are vulnerable to changes in the marine environment and also are threatened by water and noise pollution and the potential changes to fish stocks due to climate change. They may be harmed by collisions with ships, overfishing, and getting tangled in fishing gear. Offshore gas and oil development is also a threat to this species.

### Population number

According to the IUCN Red List, the total Humpback whale population size is around 60,000 animals, including estimates for specific populations: North Atlantic - around 10,752 animals; North Pacific - 18,302 animals and 36,600 whales in the southern hemisphere. The number of humpback whales is increasing today and this species is classified as Least Concern (LC).

## Fun Facts

Whales are mammals, and so they have hair, although they have very little.

The Humpback whale has this name due to the shape of the dorsal fin and the way it appears when it is diving.

Humpbacks communicate with loud, low-pitched moans, howls, and whines. They also communicate through visual cues and body language such as tail slapping, lunging, and breaching the water. This type of communication shows dominance, health, and youth during the mating season to demonstrate to others that they are fit, healthy, and good to mate with.

Humpbacks are famous for their water acrobatics. They can frequently be observed jumping out of the water, sometimes using their flukes to do so.

Calves can drink up to 600 liters of milk in a day, and within several months they develop a layer of blubber to help protect them from the cold.

Humpbacks have a diverse repertoire of feeding methods, including the bubble net technique; a group of whales dive up to 20 m (66 ft) below the surface and swim in a shrinking circle blowing air from their blowholes creating a vertical cylinder-ring of bubbles that captures the prey above them. Humpbacks use two main behaviors to create bubble-netting; upward spirals and double loops. After the nets are created, humpbacks swim into them with their mouth gaping and ready to swallow.

Humpbacks are very friendly whales that interact with other cetaceans such as Bottlenose dolphins. They may play with dolphins and protect other animals such as seals and other whales from Killer whales.

Whales are air-breathing mammals that must surface to get the air they need. The stubby dorsal fin is visible soon after the blow (exhalation) when the whale surfaces, but disappears by the time the flukes emerge. Humpbacks have a 3 m (9.8 ft), heart-shaped bushy blow through the blowholes. They do not generally sleep at the surface, but they must continue to breathe. Possibly only half of their brain sleeps at one time, with one half managing the surface-blow-dive process without awakening the other half.