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Sharks are cartilaginous fish. The skeleton of a shark is mainly made of cartilage. They belong to the class of Chondrichthyes. In particular, the endoskeletons are made of unmineralized hyaline cartilage which is more flexible and less dense than bone, thus making them expel less energy at high speeds.
Many sharks can contract and dilate their pupils, like humans, something no teleost fish can do. Sharks have eyelids, but they do not blink because the surrounding water cleans their eyes. To protect their eyes some species have nictitating membranes. This membrane covers the eyes while hunting and when the shark is being attacked.
The head or skull includes the skull roof (a set of bones covering the brain, eyes and nostrils), the snout (from the eye to the forward-most point of the upper jaw), the operculum or gill cover (absent in sharks and jawless fish), and the cheek, which extends from the eye to the preopercle. The operculum and preopercle may or may not have spines.
The entire body of a shark is a very efficient eating machine. Each organ has been fine-tuned for hunting and acquiring food.
The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory (smell) sense organ located in the soft tissue of the nasal septum, in the nasal cavity just above the roof of the mouth (the hard palate) in various tetrapods. [1]
The following outline is provided as an overview of and topical guide to sharks: Sharks (superorder Selachimorpha) are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 440 million years ago, before the time of the dinosaurs. [1]
Shark bites are common in Volusia County, with blacktips and bull sharks mostly to blame. But the bites are rarely fatal. Here is what we know.
Why do sharks attack humans? According to the Shark Research Institute, there are over 400 plus species of shark around the world, which include great white sharks, tiger sharks and bull sharks.