In Douglas Adams's Hitchhiker's Guide to the Galaxy it falls to the dolphins to alert man of the imminent destruction of planet Earth. Sadly for the human race, the leaping sea mammals' desperate attempts to warn of an encroaching interstellar bypass are written off as amusing aquatic acrobatics. As the Vogons move in, the dolphins depart, bidding mankind a fond farewell and thanking them for all the fish.
Dolphins' idiosyncratic behaviour and remarkable intelligence have long intrigued those who have been lucky enough to witness it. African fishing tribes have, for centuries, co-operated with the creatures to drive their catch into their nets; and dolphins have played their part in the wars of the 20th century, locating sea mines and detecting enemy divers.
But little is really known about why dolphins act in the way they do, especially in their dealings with the human race, and scientists are becoming increasing fascinated by the subject. It is easy to see why they have a special place in the affections of man, with their irrepressible sociability and characteristic "smile". People have always loved dolphins, from the early mariners who rejoiced at the sight of them surfing the bow waves of their ships to the New Age therapists who believe them capable of healing everything from a sick body to a broken relationship.
But what do dolphins see in us? The answers are less obvious. But we certainly seem to hold some fascination for them.
Experts don't know why but, in recent years, a growing number of these beguiling cetaceans have abandoned their characteristic social groups to take up solitary residence in inshore waters, harbours and bays. It might be a natural part of the dolphin life cycle; no one is really sure. What is understood, however, is that the phenomenon is occurring not just around the British Isles but across the world's shallow seas. And experts fear that public ignorance is creating a new threat to those very creatures which live in the closest and most visible proximity to modern man.
A familiar pattern has emerged. First the new arrival is adopted by the local community, given a name and admired by holidaymakers. Soon they make their way into the local press and then into the national media spotlight where they join a growing band of dolphin celebrities with followers drawn from far and wide – some of whom, inevitable, are looking for the much-vaunted "once in a lifetime" thrill of swimming alongside them.
Soon the dolphins become used to humans, willing to be fed and nurtured by them and – in the latter stages of this emerging relationship – even actively seeking them out. In other words, this totemic free spirit of the ocean has become, in effect, tamed.
But for the animals on the receiving end, this human attention can prove little short of a death sentence. Yesterday, the Whale and Dolphin Conservation Society, concerned at the plight of Findol, a bottlenose dolphin who allows its tummy to be tickled by admirers off Penlee in Cornwall, warned that continued interaction between man and dolphin poses a significant danger to both species.
According to the society's international director of science, Mark Simmonds, Findol is a typical example of the growing population of highly vulnerable "solitary sociable" dolphins, significant numbers of which meet a bloody end by being caught in a boat's propeller blades.
Nor is the danger all one way. Humans who venture into the sea to be close to these powerful loners – a fully grown male bottlenose can measure up to 4 metres and weigh in excess of 300kg – also face the risk of being injured or even killed by the "robust" actions of a dolphin.
In the wild, bottlenoses live in groups of up to 12 animals. They are far from cuddly and can use their powerful jaws and tails to bite and swipe fellow members of the "pod" as part of the natural cut and thrust of group life.
These often aggressive actions leave deep scars which are damaging but never fatal – dolphins being protected by a thick layer of blubber beneath a tough hide.
When they gang together, a dolphin group can happily see off large predatory sharks with a series of aggressive and co-ordinated headbutts. In Scottish waters they have been known to kill rival porpoises when food supplies become scarce.
"People have to remember these are wild animals in their natural habitat. They are very sociable animals who live in social groups whose lives revolve around interacting and co-operating with other members of their pod," says Mr Simmonds.
"But more and more we are going into their environment and over time they can become habituated to human contact relatively quickly. They can go from being stand-offish to actively seeking interaction with humans as a way of meeting the psychological needs previously satisfied in the pod."
Intriguingly, dolphins have been found to tone down their natural aggression and power when alongside human swimmers. Scientists have found dolphins are able to recognise a pregnant woman in the water through echo location. This sense is so highly tuned that they are also able to tell when a swimmer is nursing a broken limb, giving rise to reports of stricken divers being led to safety by friendly pods.
Conservationists accept that the lure of swimming with dolphins is powerful but insist the people must be alerted to the dangers of proximity. "We have to persuade people to leave them alone," says Mr Simmonds. "People's affection for these animals is so great that the temptation to jump in to the water is sometimes overwhelming".
Swimmers are running a huge risk by relying on this innate tenderness towards humans. "We have had a couple of episodes in Britain where they have tried to lure people into deep water to play or trying to keep them in the water for a little while longer because they are having a very nice time," he says. "But, touch wood, no one has been significantly harmed."
It is a different story off Brazil's Caraguatatuba beach, where a solitary dolphin known as Tiao was regularly attracting upwards of 30 bathers around him at a time. Some began grabbing on the animal's flippers while one even pushed an ice-cream stick in its blowhole. Tiao eventually struck back, reportedly leaving one man with fatal wounds.
But drawing conclusions on what motivates dolphins to become "solitary" in the first place, or why they act like they do when they come into contact with humans, is frustratingly hard.
Each creature, just as it has a unique "voice", responds to situations in different ways. Some, such as George, a lone "ambassador" bottlenose that divides its time between France, the Channel Islands and the south coast of England, with occasional appearances off the Netherlands, appears well suited to the solitary life, and scientists believe that he has become fully habituated to human contact.
A dolphin called Marra, on the other hand, which drew crowds eager to witness its antics off Maryport in Cumbria, succumbed to blood poisoning after cuts, possibly caused by a swimmer's jewellery, became contaminated with harbour pollution. Jet, a dolphin which took up residence off Portsmouth harbour, died in the blades of a reversing tug boat. And fears are mounting for the safety of Dave, the misnamed female bottlenose, currently at home off the Kent coast.
The number of bottlenose dolphins, the best known of the two dozen species of cetaceans that live around the British coast, is in decline. Once present in almost every fish-rich estuary, today they are reduced to two rump populations.
Some 200 live in the waters of Cardigan Bay in west Wales while a pod of about 125 make up the world's most northerly population in the Moray Firth off Aberdeenshire (although it is declining). It is thought another population exists off the west coast of Scotland.
Across the world, the bottlenose is yet to join the endangered list but its numbers remain under threat from man's growing exploitation of the ocean.
One growth area that is worrying conservationists is the explosion in the number of places offering "swim with dolphins" activities for tourists. No longer confined to Florida theme parks, they are springing up across the developing world, where poor fisherman have found that a captured dolphin, kept in often cruel and inadequate conditions, provides a more reliable revenue stream than the declining catch.
The belief that dolphins have spiritual or healing powers has fuelled demand. But there is little evidence to support the claim.
Unfortunately for dolphins, they continue to exert a powerful grip on the human imagination. And, in the end, it will be down to us to save them.
* Findol has been befriended by sailors and lifeboat crews off the Cornish coast this summer. The dolphin is thought to have travelled west from Plymouth Sound in Devon.
* Dave the dolphin first appeared off the coast of Kent between Seabrook and Folkestone in April 2006. "He" was later discovered to be a female.
* Marra was the focus of a rescue operation after being stranded in the marina at Maryport, Cumbria. It was taken back to open water but later died, probably as a result of pollution.
* Jet the dolphin was killed after colliding with a propeller in Portsmouth harbour in 2006.
* Fungie, first arrived in Dingle Bay, south-west Ireland, in 1984 and has become an official tourist attraction.
* In 2002, George the dolphin became a regular visitor to French, British and Dutch waters and is often sighted.
Naomi WalkerReuse content