One of the first questions that would come to most people’s minds when they hear about sharks is what do sharks have bones for. They have certain predatory carnivores that have bones and keep the bones, called osteofauna, in their bodies. Sharks are one of such carnivores. In fact, sharks are one of the only creatures to possess a complete skeletal system, including the head, jaws, thorax and tail, with no joint or cartilage.
The osteofauna are the specialized bones of sharks that include their jaws, snout, pelvic bone, pelvic girdle, ribs and scapula. These bones help sharks defend themselves and their prey from enemies. Sharks have evolved from their more primitive ancestors, which date back to the Triassic period. At this time, there was not much difference between sharks and other fish in their physiology, except for the fact that sharks lived mostly in deep water. Gradually, sharks developed their cartilage in order to help them move in the water better and with greater speed.
Sharks have several kinds of cartilage, the most important being the osteoblasts, which are also known as osteocytes. The osteoblasts produce new cartilage for the shark’s skeleton. In fact, sharks have evolved into an amazing pattern of development when it comes to their cartilage, particularly their skeletons. They constantly build new bones and remodel their old skeletons to adapt to changing environments. Sharks have adapted well for their aquatic lifestyle.
When it comes to their eyes, sharks have evolved into excellent divers. Eyes of a shark are made up of several kinds of photoreceptor cells (these are responsible for the fish’s color vision). The pigment that is responsible for making the red color of a shark’s eye is also present in these photoreceptors. It is believed that these colored pigments serve as an indicator of food sources. Other kinds of photoreceptor cells are located in a shark’s brain and they are responsible for the fish’s hearing. Although not as prevalent in sharks, each shark has a small central nervous system which is responsible for the fish’s balance and behavior.
Another interesting characteristic of sharks is the presence of a “hammerhead.” A hammerhead is a conical shaped cephalothoracic structure at the end of a shark’s dorsal fin. The primary function of the hammerhead is to hold the shark’s head up in the water so that other predators can see it. Although these sharks have powerful bite weapons, they are not very efficient when it comes to capturing their prey. A great favorite among sport sharks, the hammerhead makes its catch using a specialized lure.
Another structure present in sharks that is useful for grabbing food is the triangular mandible or “shank.” The main body of the Shank consists of a single bone, and it has two paired sigma bones at each side. The triangular mandible serves as the shark’s mouth, allowing it to grasp and crush its food. Although the teeth are used primarily for eating, the mandible is an important part of the shark digestive system as it houses the tubular muscles that aid in filtering food particles. Sharks have evolved from a bony diet consisting mainly of meat and arctic seafood that slowly evolve into a bony carnivore.
Another characteristic present in sharks that helps them to hunt is their great white shark teeth. The great white shark teeth is one of the most distinctive characteristics of all sharks and is the reason these sharks are called sharks. The large number of teeth represents the shark’s ability to catch its prey by biting into the skin of its prey. These teeth are composed of an outer layer of soft tissue that surrounds and protects the sharp inner portion. Unlike other sharks, great white sharks have few teeth that grow back once they have been removed from their victims.
Sharks have a unique anatomy unlike any other marine organism. It is composed primarily of cartilage rather than bone, which make their immune system and regenerative abilities much more efficient and less prone to disease. Because of this, sharks are often less susceptible to illnesses such as pneumonia and chondritis, which are often caused by lack of oxygen and other environmental irritants. These immune system concerns are especially relevant for the Great White shark, which lives in waters ranging from the Atlantic to the Pacific Ocean and is known to inhabit territories up to six miles long. Other examples of cartilaginous marine organisms include the common jellyfish, some mollusks (including the great jellyfish, found in Tahiti), and the common scallop.