What is a shark?
Sharks are a group of carnivorous oceans who with 368 different species in a total of 30 families. Some kinds of shark, such as the Great White, are infamous among people because they participated in attacks that led to severe injuries and sometimes death. In general, however, sharks are shy fish who will not attack unless they are provoked.
Sharks have existed since prehistoric times, fossils suggest that sharks have maintained their basic shape and evolutionary adaptation for millions of years. Fish are simple, effective and relatively intelligent, with evidence indicating that sharks can acquire skills at the same level with many ground animals. Some sharks are threatened because of the heavy human trade, including many large species of sharks.
Sharks ranges from the size of the pygma shark, which is seven inches (18 centimeters), to the whale shark, which can reach a length of 50 feet (15 meters). Most sharks have a gray upper part and pale lower bodies for maskovací í í Sharks have several other characteristics that distinguish them from most fish, starting with their skeleton, which is created more from cartilage than bones. As a result, sharks are stronger and more flexible than many fish species.
Sharks also have harsh skin with sand, which can be quite painful to the touch. In addition, shark teeth will be returned if they are released, which guarantees an impressive lifelong teeth. Many sharks also have a slightly serrated teeth. The sharks have more gills on each side, with some types of up to eight, while most are between five and six.
Most sharks have streamlined bodies designed for efficient water movement. Many species have protruding dorsal fin and all have divided caudal or rear fin. The shark can move very quickly in search of prey and depending on the size of the air, sharks eat small food, plankton, molluscs and koRides.
Sharks can be found around the world, inhabiting mild waters and tropical, with some species preferring shallow water. Shallow types of water may pose a risk to humans, because sharks will feel threatened by swimmers, surfers and the like, and they can attack if they feel in the corner, or if they think of a prey. Swimmers should avoid areas known to have sharks and also to realize their environment. If attacked, biologists recommend that the victims prevent in all possible ways.
Shark meat is consumed by many cultures, although growing mercury levels found in shark meat make this consumption unpredictable. Shark first values are highly valued, leading to a global threat to the species of sharks.