A dying legend in its own lunchbox

IN A PLASTIC lunchbox, a single snail is experiencing the ultimate loneliness. It is the last of its kind. When this small mollusc dies, its species will enter the eternal night of extinction.

The snail, Partula affinis, is the only current member of a small and exclusive club of species which, having been wiped out in the wild by man, linger on in zoos and laboratories awaiting the end. One of the best-known late members is the passenger pigeon, which once darkened North American skies, until the white man came with his guns. The last recorded shooting of a wild bird was in 1900. The final passenger pigeon, named Martha, died 14 years later in Cincinnati Zoo at the grand old age of 29. She had spent her entire life behind bars.

And now, less glamorous but just as doomed is the sole Partula affinis in Professor James Murray's laboratory at the University of Virginia, Charlottesville.

It shows no sign of Angst, but snails are not noted for needing company or showing emotion. It is kept warm and moist and eats a diet of trout pellets, dog vitamin supplement and porridge oats.

The species is one of hundreds living on South Pacific islands which have been or soon will be wiped out thanks to reckless tampering with nature. In the 1960s, giant African land snails were introduced as meat for the islanders, but they began to gobble up crops. So a small, aggressive predator snail from central America, Euglandia rosea, was introduced in the hope that it would eat the giants. But it found them too big and tough-shelled, and instead began to wipe out the native snails in Polynesia and Hawaii.

This infuriated geneticists who had made Partula a large part of their life's work. For, like Darwin's finches, the snails provided a wealth of clues on the creation of new species.

Professor Bryan Clark of Nottingham University, like Professor Murray, has been studying and collecting the many species of Partula for about 30 years. 'They were a brilliant natural experiment for us to study in the laboratory and the field, until some nitwit introduced the carnivore,' he said.

The two professors have found out how to keep some 30 species alive in the laboratory, and passed on snails and husbandry techniques to zoos. So, while many have become extinct, some may one day be reintroduced into their native island forests if Euglandia is ever eliminated.

Professor Murray collected several Partula affinis in Tahiti five years ago, as the predator closed in. They had babies in the laboratory, but none survived. The adults gradually died, leaving just the one. It may have years to live, for Professor Murray knows of one snail, albeit a different kind of Partula, that lived for 18 years.

He has not named the doomed mollusc. 'You could say it is a very special individual, but it's a rather futile kind of specialness,' he said.

As a hermaphrodite, the snail theoretically has one very impressive survival trick up its shell. It produces both eggs and sperm and could mate with itself to produce young - Partulas have done this in captivity. But this very particular Partula shows no sign of indulging in autosex.