鯊魚的特徵(英文)

Established in 1997, the Shark Trust is the UK registered marine charity dedicated to promoting the study, management and conservation of sharks, skates, rays (elasmobranchs) and chimaera. The Trust works through a series of scientifically supported campaigns, research and education programmes, and strives to provide guidance, facilitate decisions, influence legislation and raise awareness.

The Shark Trust is the UK member of the European Elasmobranch Association. As such, it collaborates with other national member bodies to achieve their aims in British, European and international waters. The Shark Trust is led by a board of Trustees, who oversee a small but dedicated Conservation and Administrations team, a voluntary Scientific Committee, and a growing number of committed supporters.

The Trust works not only with the general public but also a wide range of specialists groups including divers, boat owners, politicians and fishermen. The Trust is in favour of sustainably managed fisheries and works with both commercial and recreational fishers and their representative organisations in a bid to secure a future for elasmobranch stocks. The Trust believes in ‘conservation through awareness’.
The Shark Trust campaigns involve lobbying of government at UK, European and international levels. Campaigning may also involve working directly with stakeholders including commercial and recreational fishing sectors and associated industries, scuba divers, yachtsmen, and the general public. The Trust campaigns in a rational manner using fact based material to support opur positions; we do not engage in direct action. Although our activities may not necessarily grab headlines, they do get results!

The Shark Trust's campaigns cover all aspects of shark conservation and shark fisheries management, including action against shark finning; campaigning for sustainable European management of shark, skate and ray fisheries; lobbying for improved protection through international (e.g. CITES) and domestic measures (e.g. the Wildlife and Countryside Act); as well as other national and international shark concerns on a case by case basis.

SIZE
A scuba diver above a Whale shark. The Whale shark is the largest fish in the world; the basking shark is the second largest fish.
There are many different species of sharks that range in size from the size of a person's hand to bigger than a bus. Fully-grown sharks range in size from 7 inches (18 cm) long (the Spined Pygmy shark), up to 50 feet (15 m) long (the Whale shark). Most sharks are intermediate in size, and are about the same size as people, 5-7 feet (1.5-2.1 m) long. Half of the 368 shark species are under 39 inches (1 m) long.

BODY SHAPES
Sharks have a variety of body shapes. Most sharks have streamlined, torpedo-shaped bodies that glide easily through the water. Some bottom-dwelling sharks (e.g. the angelshark) have flattened bodies that allow them to hide in the sand of the ocean bed. Some sharks have an elongated body shape (e.g., cookiecutter sharks and wobbegongs). Sawsharks have elongated snouts, thresher sharks have a tremendously elongated upper tail fin which they use to stun prey, and hammerheads have extraordinarily wide heads. The goblin shark has a large, pointed protuberance on its head; its purpose is unknown.

VARIETIES OF SHARKS
There are about 368 different species of sharks, which are divided into 30 families. These different families of sharks are very different in the way they look, live, and eat. They have different shapes, sizes, color, fins, teeth, habitat, diet, personality, method of reproduction, and other attributes. Some types of shark are very rare (like the great white shark and the megamouth) and some are quite common (like the dogfish shark and bull shark). Sharks belong to the group of cartilagenous fish, the Elasmobranchii, that includes the sharks, rays, and skates.

SKELETON

Sharks (like the Goblin Shark pictured above) have no bones; their skeleton is made of cartilage.
Sharks are a type of fish that have no bones, only cartilage. Some parts of their skeleton, like their vertebrae, are calcified. Cartilage, a strong fibrous substance, is softer than bone; our nose and ears are made of cartilage.

Sharks belong to the group of fishes called Elasmobranchii, which also includes the rays, skates, and ratfish. The Elasmobranchii are all fish that have no bones, only cartilage.

TEETH
Sharks may have up to 3,000 teeth at one time. Most sharks do not chew their food, but gulp it down whole it in large pieces. The teeth are arranged in rows; when one tooth is damaged or lost, it is replaced by another. Most sharks have about 5 rows of teeth at any time. The front set is the largest and does most of the work.