Overview of Great White Sharks
Marsida Barjamaj
BIO 132
Prof: Mark Frageau
Overview of Great White Sharks
The planet Earth needs to change the name. I don’t understand why we have to call the planet Earth instead of planet Water or Ocean where 70% of this planet it is covered from water. I have always been interested to know more about the ocean and the species which intrigues me. There are people who won’t even step foot in the ocean for fear of being eaten alive by the big predators called shark. My favorite one are the Great white shark. They are one of the most feared sea animals, enormous in size and with sharp teeth. We hear a lot of stories about the sharks and most of them are exaggerated. My question is: Are they really so dangerous or we as human made them look more terrifying then they actually are?
What is a shark and where we can find them? Shark is a part of the taxonomic class called Chondrichthyes along with skates, rays, and chimareas because they share common traits. We find the sharks in the ocean, from the poles to the tropics and from the shoreline out to the middle of the ocean. The specific of this class is that the skeleton of the species is made by cartilaginous, which is softer than the bone and more flexible. This happened because the cartilaginous doesn’t have a lot of calcium like regular bone. The sharks breathe via gills by pushing or pulling water in their mouth and out their mouth. Their metabolisms it is slow and it is constructed in that way to conserve the energy in almost all the aspect of their lives. Their body shape it is optimal for them to move through the water without having any problem. As I said before the metabolism of the shark is to slow. If a great white shark which is one of the biggest sharks will eat a dead whale 30 kg, it could survive for six weeks with only that whale.
Great white sharks are considered as cold blooded species because they have the same body temperature as the water temperature where they live. This is not true because they maintain a body temperature which is warmer than the surrounding water. The muscle activity warms their body. A warming and cooling cycle happened in the shark body because the blood in their veins goes to the gills to get the oxygen and it gets in touch with the cold water and the heat is lost and the blood get cold quickly. From the other side the heart pump warm blood into the arteries and veins and start from the beginning the new cycle of maintaining the same blood temperature as the water around. A great white shark must keep swimming to ensure a continuous flow of oxygen rich water across its gills. If it stops it suffocates.
Why sharks are so terrifying? One reason is their teeth have a shape of triangular and really sharp. The prey it is held with the lower jaw and the upper jaw teeth are cutting the prey. The skin of white shark it is covered with little tiny teeth which are just as same the big teeth which sharks use to eat with. During the evolution the micro teeth of their skin became the big teeth that they use to eat. But if you touch the big teeth you will see very soft and wobble teeth. A human being has 20 milk teeth and 32 permanent teeth which mean during our lives we have 52 teeth. The white sharks have more than that and their teeth are categorized in functional which are the first teeth that we see when a shark opens the mouth and the replacement teeth which are back in the jaws. The teeth are made by cartilage but during the evolution they are covered in hard enamel. It is interesting how a functional tooth and the replacement teeth lined up behind it make up a row. It is a continuously slowly process and the teeth are connected to a layer tissue similar to our fingernails. The tissue it is growing from the inside of the jaws and out.
The Great White sharks rarely attack humans and when they do it the surprising fact is that most people survive. It is hard to believe that huge predators with huge jaws muscles will give you such an unimpressive bite. This is happened because the jaws of the shark are not attached to the skull but it is separated and hanging free. When a shark opens its mouth the jaws can be thrust forward enlarging the size of its bite.
The Great White shark has a good sense of smell. They have the largest olfactory bulbs relative to brain mass of any shark, skate, or ray. Sharks are attracted to blood, as we all know, but some other chemicals are even more exciting. Laboratory tests have shown that certain amino acids, the building blocks of proteins, are more stimulating than blood. Amino acids would be released into the water when a fish or crab was injured or decomposing, or even was just excreting waste products, which happens more often than injury. White Sharks possess a cranial nerve in their brains that appears to be specialized for sensing chemical signals called pheromones put out by other White Sharks.