- Sharks have been around for about 400 million years - long before dinosaurs even existed.
- Sharks apparently are the only animals that never get sick. They are immune to every type of disease including cancer.
- Sharks have the most powerful jaws on the planet.
- Sharks never run out of teeth. If one is lost, another spins forward from the rows and rows of backup teeth.
- A shark may use over 20,000 teeth during its life.
- A sharks skeleton is made of cartilage, allowing greater flexibility.
- The most harmless sharks tend to be the largest, such as the Basking Shark, the Whale Shark and the Megamouth Shark.
- Two-thirds of a Sharks brain is dedicated to the sense of smell.
- Shark skin is made of denticles instead of ordinary fish scales.
Sharks (superorder Selachimorpha) are a type of fish with a full cartilaginous skeleton and a highly streamlined body. They respire with the use of five to seven gill slits. Sharks have a covering of dermal denticles that protect their skin from damage and parasites and improve fluid dynamics; they also have replaceable teeth. Sharks range in size from the small dwarf lanternshark, Etmopterus perryi, a deep sea species of only 17 centimeters (7 in) in length, to the whale shark, Rhincodon typus, the largest fish, which grows to a length of approximately 12 metres (39 ft) and which feeds only on plankton, squid, and small fish through filter feeding.