SHARK

Sharks are a group of (Selachimorpha superordo) fish with a complete cartilage framework and a slender body. They breathe using five gill burrows (sometimes six or seven, depending on the species) on the side, or start slightly behind, the head. Sharks have bodies that are covered with dermal denticles to protect their skin from damage, from parasites, and to increase water dynamics. They have a number of teeth that can be replaced. Sharks include species as large as palms. The pygmy shark, Euprotomicrus bispinatus, a species from the deep sea that is only 22 cm long, to the whale shark, Rhincodon typus, the largest fish capable of growing up to about 12 meters like a whale, only eats plankton through a filter in his mouth. The bull shark, Carcharhinus leucas, is the most famous of several species that swim in both sea and fresh water (this species is found in Lake Nicaragua, in Central America) and in the deltas.

The shark skeleton is very different compared to bony fishes such as cod, because it is made of young bones (cartilage), which are very light and flexible, although the young bones in older sharks can sometimes partially calcify, so make it harder and more like bone. The jaws of the shark are diverse and are thought to have evolved from the first gill cavity. This jaw does not attach to the cranium and has an additional mineral deposit which gives it greater strength. Sharks are generally slow to reach sexual maturity and produce very few offspring compared to other fish harvested. This has raised concern among biologists because of the increasing efforts made to arrest sharks so far, and many species are now considered endangered.

There is a popular myth that sharks are immune to diseases and cancer, but this is not true. There are diseases and parasites that affect sharks. Evidence that sharks are at least resistant to cancer and disease can be said to be just anecdotal and if there are, there are very few scientific studies or statistics that prove that sharks can increase immunity to disease. But now there are several drug companies that produce shark liver oil (Squalene) to improve the health of the liver and heart.

Source: https://en.wikipedia.org/wiki/Shark

Picture: Google