Introduction

We are in a state of transition. Thirty years ago divers were advised that the best thing to do if you saw a shark was to get out of the water. Nowadays the majority of divers hope to dive with sharks as a tourist on an African safari hopes to see big cats.

Biologists who have spent many hours watching sharks in their natural habitat have begun to observe a variety of heretofore unsuspected behaviour patterns both within and between species. The old cliches - that a shark is a shark is a shark, that they are no more than primitive eating machines, that the only good shark is a dead shark, that they have not evolved in hundreds of millions of years - are crumbling as glimpses into the considerable sophistication force a re-evaluation. But it is only a few minutes before midnight: shark species the over world are threatened with extinction.

Dive operators are now finding themselves in the novel position of being expected to offer shark dives, in which the local sharks are fed so as to bring them in close. This is something of a mixed blessing: divers who can interact with sharks underwater, who can appreciate first-hand their splendour, can and must contribute to conservation initiatives. The downside to shark feeding, it has been argued, is that regular feeds disrupt the fragile ecology of the habitats in which they occur. Further more, it has been suggested that the sharks in question lose their natural timidity towards humans: the risk of attack therefore, presumably increases. And it is certainly true that, very, very occasionally someone - usually the feeder - does get bitten.

As an underwater photographer I know full well that most sharks need to be attracted by food if they are to be photographed. And it seems to me that responsible shark-feeding operations have a crucial role to play in educating the public about the reality of sharks. The risks are small, the rewards tremendous.

There are few non-specialist books dealing with shark identification. Even fewer cater specifically for divers. Scientists often rely on a host of esoteric details, such as a tooth number and shape, vertebral count, proportion of fin height to total body length, to separate similar-looking species, but such details usually require a carcass. Most of the species discussed herein can be readily identified underwater due to certain prominent features. A few can not: for example a free-swimming Galapagos shark and Caribbean reef shark are difficult to distinguish.

The aim of this guide is to provide a sketch of the natural history and behaviour of sharks in general and then to facilitate the identification of sharks that a diver in the warm waters from Florida to the northern shore of South America is more likely to encounter. None of the species described in this guide are confined to this artificially-created region and some are ocean wanderers that occur worldwide.

Jeremy Stafford-Deitsch (Author)