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The identification, behaviour and natural history of
SHARKS of Florida, the Bahamas, the Caribbean and the Gulf of Mexico |
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SHARK TRUST | USEFUL LINKS | BUY THIS BOOK |
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THE IDENTIFICATION, BEHAVIOUR AND NATURAL HISTORY OF SHARKS OF FLORIDA,
THE BAHAMAS, THE CARIBBEAN AND THE GULF OF MEXICO This book was written by Jeremy Stafford-Deitsch to provide a sketch of the natural history and behaviour of sharks in general and then to facilitate the identification of sharks |
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 HOME >> TIGER SHARK >> BOOK CONTENTS >> READ INTRO >> |
(An extract from the book) Sharks and their relatives Sharks belong to an ancient and extraordinary side-branch of evolution that can be traced back some 400 million years in the fossil record. The group includes two other remarkable classes of fish: rays and chimaeras. (The term skate refers to members of the same group as the rays.) Rays are familiar enough to divers. Their more impressive members include the eagle ray Aetobatus narinari and the manta ray Manta birostris. Pioneering research on the eagle ray in Bimini, the Bahamas, has shown that this is a highly social animal equipped with a dozen or more behaviour patterns, such as dipping, which are performed by one animal to another. Furthermore, the foraging, aggregating and socializing activities of the Bimini eagle rays appear to be geared to specific phases of the tidal cycle. The rays disperse at high tide and forage far afield as the tide begins to fall. At low tide they aggregate in specific core areas. Several of the larger predatory sharks include rays in the diet. Given the tendency of such sharks to move into shallow water on a rising tide, it is interesting to ponder whether the movements of the eagle rays are, at least to some degree, designed to minimize confrontation with such sharks. Chimaeras are small, mostly deep water creatures that are grouped with sharks and rays as much by default as by design. They are rarely seen by divers. The vast majority of the world's fishes, some 95 percent , have a bony skeleton and are collectively termed bony fishes. The skeleton of sharks, rays and chimaeras is composed of cartilage and they are often referred to as cartilaginous fishes. In fact cartilaginous fishes differ from bony fishes in a wide variety of ways including their reproductive system, skeletal structure (for instance, ribs, which when present, do not protect the internal organs), sensory mechanisms, the composition of the skin and the lack of a swim bladder. Furthermore, sharks and rays have numerous gill openings on each side of the head or body (normally five), although chimaeras, like bony fishes, have only one. Indeed, so different are the cartilaginous fishes from the bony fishes in so many fundamental details that some experts wonder whether the former should be called fishes at all.... |
SANDBAR SHARK Sharks are magnificent and integral components of the ecosystems in which they occur. Divers who are fortunate enough to observe these animals underwater have a duty to champion their protection GREAT WHITE SHARK  The retracted teeth of the upper jaw and also replacement teeth in the lower: sharks constantly grow new teeth to replace old ones and get though thousands in a lifetime  conserve, preserve, understand |
