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Shark Facts 
 
 
  • One-third of European sharks qualify for the IUCN Red List of Threatened Species.
  • Sharks have roamed our seas for more than 400 million years, which means they inhabited the earth for nearly 200 million years before dinosaurs.
  • Sharks are fish with skeletons made of cartilage instead of bone, but sharks’ slow growth and late maturity mean they have more in common with sea turtles and marine mammals than bony fish such as flounder or tuna.
  • Sharks are a remarkably diverse group of fish. They range from less than a metre to 20 metres in length; they are found in most coastal regions but also in the deep ocean and even in fresh water. Some sharks lay eggs, but most give birth to live young. Most are top predators while a few feed on plankton. Sharks in turn are preyed upon by other sharks and sometimes killer whales.
  • The term ‘shark’ often refers not only to shark species but also to the closely related rays and skates, as well as the oft-overlooked chimaeras (rat, rabbit and elephant fish).
  • Collectively these cartilaginous species are known as chondrichthyan fish (forming Class Chondrichthyes).
  • Sharks have seven senses – the five that they share with humans, plus an electrical sense (small pores detect minute electrical currents in the water) and a lateral line (pressure sensitive cells beneath their skin), both of which help them detect prey and avoid predators. 
  • A shark’s brain shows the importance of smell to sharks – up to two-thirds of its brain's total weight is made up of olfactory lobes, which analyse smell.
  • The two largest shark species – basking and whale sharks – can grow to more than 10 and 20 metres in length, respectively, but feed only on the tiniest fish and plankton. Although protected by several countries, these slow-moving filter feeders remain at risk while migrating across unprotected waters.
  • Female spurdog (spiny dogfish) have one of the longest gestation periods of any animal, carrying their pups for nearly two years. Indeed, females from the Northeast Pacific don’t reproduce until they are 35 years old. This makes them extremely vulnerable to overfishing as they are slow to repopulate once depleted.