Sharks - What Are They?

Sharks! Does this name bring a sense of fear in your mind? Or you just get excited by hearing the name. Today I am going to tell you each and everything about sharks; from their body structure, to eating habits, to myths and facts associated with them. So let's begin with something general about them.

Sharks are the members of Chondricythyes class that have full cartilaginous skeleton and a streamlined body. Rays and skates also belong to the same class, so sharks are very close relative of rays and skates. Shockingly most of them relate to rays more rather than other sharks. They like all other fishes, respire through gills and not through lungs as mammals do. Sharks have canine teethes which are not attached to the jaw, rather are embedded in the skin. Their teeth are the most surprised beauty that God have given to them. Sharks physical structure is quite varying. Sharks can be too small just 22 centimeters long such as pygmy shark or can be too large up to 13 meters like white shark. Until now, more than 360 species of the sharks have been discovered. The most notable of all is Bull Shark.

Sharks Physical Structure:

They have cartilaginous skeleton which is very light and quite flexible than bone. This helps sharks in swimming under water and covering long distances easily. Their skin is often guarded against parasites and other damages because of dermal denticles covering. All sharks have streamlined bodies though few of them have broad fins at the end. So like other fish species they also swim swiftly though they have bulky bodies.

Sharks teethes are not attached to the jaw but they are rooted into the flesh of the mouth. This may be because they need more piercing power when attacking their prey. Interesting fact about sharks teethes is that on an average, single shark can loose 30,000 teeth in a lifetime. Sharks have tails that give them speed and acceleration. The structure of the tail varies from shark to shark. Shape of the tail gives shark the ability to survive and prey in different environments.

Sharks respire through gill slits that are located just next to head before the pectoral fin. They also have spiracle, a modified gill, right above the head though which they intake water while respiring. This spiracle plays important role for the bottom dwelling sharks where the oxygen concentration in the water is quite less. Sharks eyes are covered with a tissue called tapetum lucidum that made them perfect for marine environment. Sharks life span may be from 20 to 30 years.

Sharks Eating Habits and Reproduction:

Sharks are carnivore. They can eat anything from small fishes, crabs, turtles, large fishes, and even other small sharks. They prey in groups whether they are preying on the top of the water or at the bottom. Their technique to attack may vary from species to specie. Some sharks swathe their prey and then kill the weak ones while other sharks prey using hidden attack technique. But one thing is common to all of them. They are aggressive. Yes and this aggressiveness have even encouraged them to humans too. Sharks have olfactory glands that let them sense even a one part million of blood in the water. They do have hearing power too.

Reproduction in shark is very rarely observed. While some sharks reproduce by curling around the female shark whereas other shark the big ones often mate swimming parallel to each other. One can easily distinguish between male shark and female shark. Males have modified pelvic. Males attract females by biting them. Sharks produce pups either directly or safeguard them using egg cases unlike eggs laid down by other fishes. Sharks can even mate without the need of any male partner.

This all told about their structure, eating habits and reproduction, let's know move towards some rumors associated with them. In direct words, sharks don't prey humans though few shark species are dangerous for humans. They don't like to feed on humans. So then what about the stories associated with the sharks attacking the humans? Sharks attacks on us only if they feel being trapped or when someone comes their way. Usually sea-divers and water surfers are the victims of shark's attacks. Sharks like to ride on high tides and hence often attacks surfers coming their way. We people often think that white sharks are the deadliest underwater creatures but some divers had reported to go as close as to them without a fear of being getting hit by white sharks though few precautions are needed.

So get yourself out of the false stories associated with sharks and show your respect towards them. Shark killing has been increased in past 50 years. Even some of the shark species have gone extinct. This is the time to save them and protect them. They are of huge importance to us and nature. Nature has created every creature with pre-defined goals and we should co-operate with nature as much as possible. That's it!

You can view the full article here at http://fish-species.blogspot.com/2008/05/sharks.html