Реферат: Dogfish Sharks Essay Research Paper Classification of
Dogfish Sharks Essay, Research Paper
Classification of Dogfish sharks
Kingdom Animalia (animals)
SubPhylum Vertebrata (vertebrates)
Class Chondrichthyes (cartilaginous fish)
Subclass – Elasmobranchii (sharks and rays)
Order – Squaliformes (dogfish sharks)
Sharks are fish that have been around longer then dinosaurs
have existed. They live in waters all over the world, in every ocean, and even in some rivers and lakes. Sharks, unlike other fish, have no bones; their skeleton is made of cartilage, which is a tough, fibrous substance, not nearly as hard as bone. 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 long to up to 50 feet long. The average size of sharks is between 5 and 7 feet long and they have a variety of body shapes. Most sharks have streamlined, torpedo-shaped bodies that glide easily through the water. Some bottom-dwelling sharks have flattened bodies that allow them to hide in the sand of the ocean floor. Some sharks have an
elongated body shape, snouts, and tail fins, which they use to catch prey. 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 and some are very common (like the dogfish shark ). Sharks may have up to 3,000 teeth at one time. Most sharks do not chew their food they gulp 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. Sharks vary greatly in their diets, but they are all carnivores. Some like the hammerhead are swift predators that eat fish, squid, other sharks, and marine mammals. Some are slow-swimming predators that crush and eat shellfish from the ocean floor. Others are filter feeders that sieve tiny bits of plankton and small animals from the water as they swim with open mouths. They eat huge amounts of these tiny animals and plants. Sharks live in oceans and seas all over the world, and even in some rivers and lakes, especially in warmer waters. Some sharks live near the surface, some live deep in the water, and others live on or near the ocean floor.
Some sharks live in relatively warm waters (hammerheads, bull sharks, and tiger sharks). Other sharks, such as the thresher, mako, basking and blue shark, live in temperate water (which is neither hot nor cold). Others, including the dogfish, live in cool waters. Some sharks stay in the same region their entire lives while others travel across oceans. There are three different types of sharks when it comes to migratory patterns: Local sharks – these sharks do not migrate, and range only about a hundred miles from their habitat. Examples include the bull shark, bonnethead shark, and the nurse shark. Coastal pelagic sharks – these sharks can migrate over 1,000 miles (1,600 km). Examples include the dusky shark, the tiger shark, and the sandbar shark. Highly pelagic sharks – these sharks migrate across oceans. Examples include the blue shark and the mako.
Scientists have shown that sharks are relatively intelligent and
can learn at a rate similar to that of rats and birds