Lifeguards of the deep

When Adam Maguire and his two friends Jason Maloney and Bradley Thompson went surfing at Halftide Beach, in New South Wales, early in January 1989, they found themselves in exhilarating company. For an hour or more, a school of dolphins played with them in the surf, riding in on the waves towards the beach.

But then the dolphins became agitated, splashing and turning in the water, and making loud clicking and whistling noises. It was then that Adam saw the fin of a shark speeding towards him through the waves.

Before he knew it , the shark had attacked, biting a large chunk out of his surfboard and knocking him into the water. He hit out at the shark with his fists, but it bit him in the stomach and side. Adam thought the end had come. Then the dolphins came to his rescue. They surrounded the shark and drove it out sea by ramming it with their beaks.

A friendly push

The dolphin has a reputation for being friendly to humans, and there have been many other reports of dolphins rescuing people in distress - chasing off attacking sharks, pulling drowning sailors to the surface, even guiding them to dry land. In 1945, a woman swimming off a beach in Florida was pulled under by a strong current. As she struggled to get her head above water, something pushed her violently from behind and she landed on the beach, face down. When she looked around, no one was near - but a dolphin was leaping through the waves, 6 m (20 ft) from the shore. In 1983, a Dutch helicopter pilot was helped by a dolphin after he had crashed into the Java Sea; for nine days the dolphin swam beside his rubber life raft, nudging it along until it at last reached the coast.

It is tempting to believe that we do have a special affinity with these gentle, intelligent creatures. But would an animal really take the trouble to save a human being, in some cases risking its own life in the process?

Blind instinct

Dolphin expert Dr Margaret Klinowska, of Cambridge University, believes not. She says that when attacking sharks, dolphins are only following a natural instinct to defend themselves; indeed, the presence of humans is probably coincidental. As for pulling people to the surface or pushing stranded boats along in the water, these too are probably instinctive reactions useful for the survival of the species: a dolphin is born underwater, but its mother immediately nudges it to the surface so that it can start to breathe. Perhaps the Dutch helicopter pilot's dinghy seemed to be no more than a struggling baby to the dolphin that guided it to safety.