A social creature celebrated for haunting songs and huge leaps

All whales are charismatic, but some are more charismatic than others, and Megaptera novaeangliae – the humpback – is the most charismatic of all, at least to many people who have spent time whale-watching.

It's quite different in appearance from the other great whales, with its gigantic, largely white flippers or pectoral fins which gave it the first part of its scientific name – megaptera in Greek means "great-winged". Sometimes it lies on the surface and slaps these protuberances on the water, making a loud noise, for reasons no one has yet worked out.

Sometimes it sticks its tail out of the water, swings it around, and slaps that down on the surface too, with a report like a gunshot. This is called "lobtailing" and no one knows what that's for either. But it's fascinating to watch, and it's a good bet that it's a signal to the rest of the pod in which a humpback lives.

For humpbacks are intensely social animals, journeying together every year in great migrations from warm tropical waters where they breed and calve, to Arctic waters where they eat. It's a trait that can be seen in their co-operative hunting, in which they use bubbles to deadly effect. The hunters form a circle around a mass of krill, or small plankton, then blow a wall of bubbles around it as they swim to the surface in a spiral.

This has the effect of concentrating the prey on the surface in a dense mass, which the humpbacks then scoop up. They can eat a tonne of krill at a time, and they need it: a humpback can weigh 50 tonnes and its heart alone can weigh as much as three adult humans.

Even a new-born baby humpback, which is up to 15 feet long at birth, can weigh a tonne. It feeds frequently on its mother's rich milk, which has a 45 per cent to 60 per cent fat content, and is weaned to solid food when about a year old.

Each female typically bears a calf – with a gestation period of 12 months – every two to three years. Humpbacks reach sexual maturity at six to 10 years of age, when males reach the length of 35 feet, and the larger females reach 40 feet.

Maybe that's what their singing's about: courtship. The humpback is famous for its songs, a haunting series of echoing booms and moans which travel through the ocean for many miles, and which last for several minutes at a time, before being precisely repeated.

One authority describes this as "the most complex non-human vocalisation yet known" and it is almost certainly a form of communication with its fellows.

Whales in the North American Atlantic population sing the same song, and all the whales in the North American Pacific population sing the same song.

However, the songs of each of these populations and of those in other areas of the world are entirely different. The most complex songs are heard in warm water where mating takes place, so perhaps there is love in there somewhere.

That certainly seems natural to anyone who has seen the humpback's most celebrated trick, breaching – suddenly hurling its giant body right out of the sea, leaping clear into the air before plunging back in a colossal splash.

I witnessed it last summer on a whale watch with my wife and two children on the Stellwagen Bank off Cape Cod, Massachusetts, where humpbacks gather to feed, along with minke and fin whales.

The minkes and fin whales were fine sights – we felt we were at a whale convention – but they were as nothing compared to the display you could only term Humpback Surprise.

We saw one soar out of the water with no warning whatsoever, turning in the air like a diver with a half-twist. The whole boat was gobsmacked. It may have been doing it to get rid of barnacles, but I had the feeling it had actually jumped for sheer joy. It was an unforgettable spectacle from an unforgettable creature.

The Japanese do not need to add it to their target list; there are plenty of the minke whales they are already taking to satisfy their wish to hunt and their market for meat. It's simply a gratuitous extension of the wish to kill, like a fox in a henhouse killing everything in sight.

But foxes act purely on instinct, and humans are meant to have reason; and the fact Japanese whalers now want to fire explosive harpoons into one of the world's most wonderful animals strikes me as barbaric in the extreme.

The humpback's tail...

Male humpbacks are up to 48ft long; females are up to 50ft long. They can weigh up to 30 tons.

Humpbacks eat up to one and a half tons of krill and small fish such as herring every day.

Female humpbacks give birth every two or three years to calves which weigh up to two tonnes and are 15ft long.

Humpbacks feed using a method known as "bubble netting", in which up to 22 whales will corral a school of fish into a circle by blowing bubbles into the water above them, thus allowing several of the whales to lunge up to the surface, shovelling the fish into their mouths as they do so.

Humpbacks are found in every ocean and are divided into separate stocks, one on either side of the north Atlantic and North Pacific, and seven in the southern hemisphere. They were thought to be entirely separate, but in fact breeding groups in each ocean basin do mix.

The humpbacks that feed in Antarctic waters, south of Cape Horn, and travel north to breed off Colombia and Costa Rica, make the longest confirmed migration of any mammal.

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