As a writer, I’ve studied whales around the world — from majestic blue whales off Sri Lanka to the playful humpbacks of Cape Cod. But it is the enigmatic sperm whale which fascinates me.


It has the biggest brain of any animal — a massive 18lb to our human 3lb — yet we really have no idea what it does with it.

This magnificent predator — at 65ft long, the greatest that has ever existed — spends 90 per cent of its life in the profound depths, able to dive deeper than any other animal.


For precisely that reason, it is the least studied of all the great whales. And of all whales, it is under the greatest threat, too — from what we humans are doing to its environment. Only now are we beginning to understand these creatures. But is it too late?


This week the results of the first Whale Symposium ever held in Britain were published in a book I co-edited.


It contains new scientific research revealing the true nature of this most mysterious ocean giant, but also the devastating impact we humans are having on them — not least because we pollute their habitat with plastic bags and other waste — and the terrible problems they face as a result. 


The sperm whale is a natural submarine, a miracle of evolutionary engineering. It is actually able to change the physical shape of its body to accomplish its dives.


A sperm whale can dive down for more than a mile, to depths which would crush a human being’s internal organs at a pressure of 500lb per square inch. 

In just five minutes, it can reach a depth of 500 metres, the limit at which a human diver can work. 


Soon it will far exceed that, reaching 1,000m — its favoured hunting ground. We do not know exactly how the whale’s body resists such pressure. But it must be comfortable down there, since it can spend two hours underwater.


In the inky darkness, the whale hunts by using its sonar as a sweeping scan, in search of its favourite food: squid.


Their prey ranges from shoals of creatures little bigger than cuttlefish to gargantuan giant squid up to 50ft long.


As they zone in on them, the whales appear to communicate in strange growls and buzzes. Are they indicating the direction and source of their food?  Maybe they’re just happy at eating.


Each sperm whale must consume up to 1,000 squid a day — that’s 1,100lb or half a ton of calamari! Although it has a 10ft-long jaw studded with 42 of the biggest teeth in the animal kingdom (each up to 2ft long), it does not bite its prey.


Instead, it sucks up its food like a giant vacuum cleaner, swallowing the squid whole. We know this from the stomach contents of dissected whales.


For centuries man has hunted the sperm whale, principally for that precious oil in its pugnacious head. Before the discovery of mineral oil, sperm whale oil burned in street lights and oil lamps. It lubricated the machines of the Industrial Revolution.


In 200 years we managed to reduce their population from two million to 360,000. 


Luckily, most of the world no longer hunts these beautiful creatures. But now, tragically, there are new dangers to their wellbeing.


By virtue of its position at the top of the marine food chain, the pollution we dump in the sea affects sperm whales more than any other creature.


One of the greatest problems faced by any marine species is the sheer amount of plastic in the ocean, especially plastic bags, as has been highlighted by the Daily Mail’s campaign against the profligate use of them.


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