As a new exhibition about sperm whales opens, biologist Hal Whitehead describes the fascinating mechanisms of this creature
Sperm whales are the subject of a new exhibition Photo: CHRISTOPHER SWANN/CORBIS
From Herman Melville to JMW Turner, writers and artists have long been fascinated by the sperm whale. Scientists, too, have been drawn to the creature, whether trying to understand the mechanisms behind its deep dives, the strange sounds it makes or its impact on the oceans.
But for me, there is one question that overshadows all the others: is there any other being that bundles together so many extremes? Sperm whales are the largest-toothed animals in the world, have the longest intestines, the biggest brains and the largest noses. Their dives may be the deepest and longest of any mammal – and even with their numbers drastically reduced by whaling, they still take as much food out of the ocean each year as all of mankind’s fisheries put together. They live in the deepest oceans, ranging from the equator to the edges of the ice caps (the females live mostly in the tropics and the males, which are three times larger, at the poles). And such is their impact on the planet that the iron in the faeces of Antarctica’s sperm whales fertilises enough phytoplankton to slow the impact of global warming.
This Friday, the impact of these marvellous creatures will be celebrated in the Peninsula Arts Whale Festival, a three-day festival exploring the art, writing and films that sperm whales have inspired, from Melville’s Moby Dick to Turner’s The Whale Ship. Indeed, ever since 1712, when a whaling ship from Nantucket became the first commercial vessel to slaughter a sperm whale, we have been closely linked: sperm whales were the mainstay of the oil industry from about 1750 to 1860, and became a major target at the peak of modern whaling in the 1960s.
Sperm whaling was an important force behind our exploration of the oceans, and thus of the movement of animals, diseases and genes around the world. But the whalers’ focus was on the whale’s most extraordinary feature: its nose. About a quarter of the whale’s body is taken up by its massive snout, properly called the spermaceti organ, which is filled with a very fine grade of oil. This spermaceti was the oil that drove the Yankee whalers, lit the homes of the wealthy and lubricated the Industrial Revolution.
But what do sperm whales themselves use their nose for? For a long while, scientists speculated that it might be an aid to diving or, after Moby Dick, a battering ram. The function of the spermaceti organ was finally nailed down about 10 years ago by the meticulous studies of the Danish scientists Bertel Møhl, Peter Madsen and their colleagues. They discovered that the spermaceti organ is actually the basis of the most powerful sonar system in the natural world, which gives the sperm whale a major advantage in the hunt for the elusive resources of the deep oceans. That, in turn, enables them to maintain their vast bodies and huge brains, which account for their ecological success.
Yet just as fascinating as the whales’ bodies are their minds. The fact that they evolved this all-conquering nose meant that sperm whales were now largely competing with each other for all that deep-water squid. This competition, as well as the threat of predators, in the form of killer whales, has turned sperm whales into intensely social animals. As Thomas Beale, a surgeon on a 19th-century whaling ship, noted: “The females are very remarkable for attachment to their young, which they may be frequently seen urging and assisting to escape from danger with the most unceasing care and fondness. They are also not less remarkable for their strong feeling of sociality or attachment to one another; and this is carried to so great an extent, as that one female of a herd being attacked and wounded, her faithful companions will remain around her to the last moment, or until they are wounded themselves.”
It is this aspect of the sperm whales’ existence, in fact, that has been the focus of my research over the past 28 years. I go to sea in a 40ft sailing boat, listening for the powerful clicks coming from the spermaceti organs and using them as a beacon to locate the groups. We can identify the sperm whales individually by photographing their tails – raised into the air at the start of their deep foraging dives – as each has a distinctive pattern of marks.
When the early whalers saw the huge, mature males surrounded by attentive females, they assumed they were watching a harem. But actually, it is the women who are the constant presence in each others’ lives, sticking together in family-based units of about 10. These groups of mothers and daughters stay together for their entire lives, travelling over thousands of miles, defending themselves communally against killer whales, and babysitting and suckling each others’ offspring while the other mothers are making deep dives.
The males, by contrast, swim down from the cold waters to mate – but when we followed the female groups, we saw that they would join them for a matter of hours at the most. Sometimes the females seemed more than indifferent, literally turning their tails to the incoming giant. Other males were clearly more welcome, with the females gathering closely around him, touching and stroking. Female preference seems to have a large role in the mating process.
The sperm whales’ social structure has other levels. Most striking are the clans, which we discovered from my colleague Luke Rendell’s analysis of “codas”, the patterned series of clicks that sperm whales use for communication. The females off the Galapagos Islands belong to two principal clans. There is the “regular” clan who go “click-click-click-click-click” and make convoluted tracks close to the islands, and the “plus-one” clan – “click-click-click-pause-click” – who generally move in straighter lines further offshore. Although social units from the two are often in the same general area, they only group with others from their own clan.
Studying the whales’ genes, we found no differences to explain these behaviour patterns – so were forced to conclude that the members of the clans behave differently because they have different cultures, learning particular ways of life from the elders of their unit as they grow up. In other words, sperm whales live in a multicultural society.
Culture’s profound role in the life of the sperm whale has important implications for how we see and treat the whales. Off the Galapagos, when the water is warm, the seas become less productive. Sperm whales, like most ocean life, suffer. But females of the “plus-one” clan feed better in these difficult conditions. This cultural diversity may be crucial for survival as the effects of our own human culture change the oceanic environment.
Some of the remaining mysteries of the sperm whale will soon become clear: extraordinarily sensitive tags placed on the whales using suction cups, for a few hours at a time, are beginning to reveal the whales’ life at depth, how they dive and then feed far beneath the surface. But their brains and cultures present a greater challenge. We need to probe their learning, their thoughts and values – and, in the process, give humanity a glimpse of what Moby Dick’s motivation really was.
Professor Hal Whitehead, of Dalhousie University in Halifax, Nova Scotia, will give Saturday’s keynote lecture as part of the Peninsula Arts Whale Festival, which runs from Friday to Sunday at the University of Plymouth, tel: 01752 585 050, www.peninsula-arts.co.uk
Tuesday 15 February 2011
The sperm whale works in extraordinary ways - Telegraph
via telegraph.co.uk
