When our ancestors crawled out of the primordial slime millions of years ago, the things that got left behind in the mud did not rest on their evolutionary laurels. We may think we know all about what fish got up to in the interim - after all, we eat enough of them, we keep them in tanks and we even hope that a Jurassic version lives at the bottom of a Scottish loch. But even the most unfettered imagination would be hard-pushed to concoct anything as charmingly bizarre as the "Phycodurus Equus", or leafy sea dragon.
Photographed in full flight in the Southern Ocean by David Doubilet, the dragon appears to be an extravagant exercise in marine surrealism. In fact, it is a kind of sea horse or pipe fish (scientists are not sure which), a gentle, shrimp-eating creature that rarely ventures out of the kelp forests where it lives. It can grow to up to 30cms in length but it is rarely seen.
Even so, enough have been caught for sale in Asia as aphrodisiacs to make the Australian government declare them a protected species.
For the photographer every underwater assignment like this one "is a war beneath the waves". The reason is not only the mountain of specially reinforced equipment he needs, it is also the environment itself. The undersea world is a magical demesne, but getting there requires an exacting journey - atmospheric pressure can fill a body with nitrogen bubbles (the bends) if ascents are made too quickly, and each diver has only a limited air supply.
1998 is the Year of the Ocean, and one in which the environmental pressure group Greenpeace is even more gloomy than usual about the current state of the seas that cover 75 per cent of the globe. The leafy sea dragon may have to work even greater evolutionary wonders if it is to survive the next millennium.