What is a humpback whale?

Of all the great whales, it is probably the best loved by the general public. Spectacular in its breaches, captivating in its songs, accessible in certain watching areas such as French Polynesia, the Dominican Republic or Hawaii, the humpback whale (Megaptera novaeangliae) is a worldwide emblem of marine conservation and of the wonder of the oceans. Its scientific name speaks for itself: Megaptera means “great wings” in Greek, a reference to its outsized flippers.

A giant with long flippers

Humpback whales measure on average 13 to 15 metres and weigh 25 to 40 tonnes. It is a large whale, but a more modest one than the blue whale or the fin whale. Its outline is nonetheless unmistakable: massive, stocky, with a small hump shaped protuberance just in front of the dorsal fin, which gives it its common name.

Its most remarkable signature is its gigantic pectoral flippers: up to 5 to 6 metres long, nearly a third of the body length. In proportion, these are the longest pectoral fins in the animal kingdom. They serve at once for manoeuvrability (humpback whales are surprisingly agile for their size), for communication (striking the surface with the flippers produces powerful sounds), and probably for thermoregulation (an area of heat dissipation in warm water).

Another distinctive feature: the tubercles on the head and the jaw. These small white nodular bumps are in fact modified hair follicles, fitted with long sensory hairs (the vibrissae). Relics of their terrestrial past, they probably serve to detect the movements of prey in murky water.

A tail as unique as a fingerprint

When the humpback whale makes a deep dive, it raises its tail fluke out of the water, a behaviour called fluking. The underside of that fluke carries black and white patterns that are unique to each individual, in the manner of human fingerprints. It is this feature that has made long term monitoring of populations possible through photo-identification: researchers photograph the tails and build catalogues of individuals recognisable over several decades.

The worldwide humpback whale catalogue, shared between dozens of research teams, today holds several tens of thousands of identified individuals. This method has made it possible to understand migration routes, lifespans, social structures and population dynamics at a level unmatched for wild cetaceans.

Famous songs, and cultural ones

The songs of humpback whales are among the most complex vocalisations in the animal kingdom. Only the males sing, mainly on the tropical breeding grounds in winter. Each song is made up of phrases, grouped into themes, themselves set within a structure that can last up to 30 minutes, repeated without variation for hours.

More remarkable still: at any one moment, all the males of a single population sing the same song. But that song changes over time and spreads between neighbouring populations, like a musical fashion travelling outwards. A new pattern that appears in the South Pacific may be documented a few years later among the whales of the Indian Ocean, evidence of cultural diffusion.

Bubble net feeding

The other emblematic cultural behaviour of humpback whales is bubble net feeding, fishing with a net of bubbles. Several individuals cooperate: one whale dives in a spiral around a shoal of prey while releasing air bubbles that form an impassable wall; another emits a hoarse call that disorients the fish; all rise together, mouths open, through the trapped shoal. This elaborate technique is passed on by social learning and is practised only by certain populations, notably in south-east Alaska.

Spectacular migrations

Humpback whales make some of the longest migrations known: up to 16,000 kilometres there and back between the polar feeding grounds (summer) and the tropical breeding grounds (winter). A whale that leaves the Antarctic in April can reach the warm waters of French Polynesia or New Caledonia in July, a journey of several months without feeding, on the blubber reserves built up in summer alone.

This spectacular migration offers observers extraordinary windows for watching. Whale watching operators in Hawaii, the Azores, the Dominican Republic, French Polynesia and many other regions make use of this seasonality to offer encounters with these giants, major sources of education and of public awareness.

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