What Is A Shark?

Any of numerous elongate mostly marine carnivorous fishes with heterocercal caudal fins and tough skin covered with small toothlike scales.

Sharks are ocean dwelling fish that bridge 30 different families and 368 separate species.  Great white sharks are probably the best known species because of their reputation for attacking humans causing injury and sometimes death.  Their reputation was solidified in the 1975 film, Jaws.  Unfortunately this led to many people fearing all sharks when most species are shy and will not attack unless they are provoked.

Sharks range quite wildly in size with the pygmy shark measuring only 18 cms (7 inches) long, and the whale shark measuring up to 15 metres (50 feet) long.  Sharks have existed since prehistoric times and evidence gained from fossils indicates they have changed very little over the course of millions of years.  These are simple yet efficient and intelligent fish.  Unfortunately, some species of sharks are endangered due to human desire for their fins that are used for shark fin soup and dietary supplements.  

Sharks have rough, sandpaper-like skin that can hurt to touch.  They are grey in colour with pale bellies for camouflage purposes.  Unlike other fish, sharks have a skeleton formed of cartilage rather than bone and this makes them stronger and more flexible than most other fish species.  A shark is able to re-grow lost teeth, which is of significant use to these carnivorous creatures.  May sharks also benefit from slightly serrated teeth.   Sharks have multiple gills on either side of their body with most having five or six but some having as many as eight.

With highly streamlined bodies, sharks move gracefully and with incredible power and speed through the water.  Sharks will eat plankton, shellfish, and crustaceans as well as other fish.  Many shark species have a projecting dorsal fin and all will have split caudal or rear fins.  These fish can be found all over the world and live in temperate as well as tropical water.  Some species prefer shallow water and these are often the sharks that pose the most significant risk to swimmers and surfers.  Sharks will attack if they feel threatened or if they mistake a human for regular prey such as seals.

Many popular surfing areas will post warnings if sharks have been spotted in the area and a number of beautiful beaches are permanently off limits due to high shark populations.  Biologists advise that if attacked, victims should fight back in any manner possible.

Shark fins are highly prized and has led to a number of species being threatened and shark meat is also consumed in a number of cultures.  Because sharks are at the top of the food chain, they are prone to high levels of mercury, which has led to advisories being issued regarding consumption of these fish.

Sharks are beautiful aquatic animals that spend all their time doing only 3 things... Swimming, eating, and making baby sharks. ;)