Posted by: The ocean update | April 25, 2015

11 things you didn’t know about sharks

Photo : BBC

Photo : BBC

As the BBC tries to change our perception of the ocean’s greatest predators, here are 11 surprising facts about sharks

April 25th, 2015 (Siân Ranscombe). The BBC’s natural history team spent 2,646 hours filming sharks from all around the world, for their new series, Shark. Surprisingly, in that time, there was not one single shark attack. There is far more to the species than enormous teeth and scary films…

  1. Shark attacks on humans are extremely rare. In Cape Town, where the BBC filmed footage of great white sharks hunting seals, there is an average of one attack per year.
  1. The Greenland shark is a strong contender for the loneliest creature in the world. It lives half a mile underneath the Arctic ice and swims at around one mile per hour. It does have one companion in the icy depths – the parasitic copepod Ommatokoita elongate, which has a horrible tendency to attach itself to the eyeballs of the Greenland shark, rendering it blind. Fortunately there’s probably not much to see down there anyway.

    A Greenland shark (PHOTO : BBC)

    A Greenland shark (PHOTO : BBC)

  1. It is estimated that 100 million sharks are killed as a result of commercial fishing each year. A large part of this is the popularity of shark fin soup in China. The figure is not entirely reliable, as it is believed that many of those dumped back into the sea and left to die after their fins are cut off are not included in official figures.
  1. Many larger species of shark give birth to live pups, rather than laying eggs. The gestation period of different species differs wildly as well – that of the spiny dogfish can last up to two years while the shortest, just 90 days long, is that of the whitespotted bamboo shark.
  1. There are over 30 species of shark found in the coastal waters of the UK. The basking shark has been spotted from Cornwall to the Hebrides but thankfully has no interest in humans, and largely eats plankton. If it did develop a taste for us, we would be in trouble : the second biggest fish on the planet, it can grow up to 8m long.
  1. Intrauterine cannibalism, where the largest and strongest embryo consumes its own siblings, is the name given to the survival-of-the-fittest behaviour of the ragged tooth shark’s offspring.
  1. As well as invariably having a great set of teeth in their mouths, sharks’ bodies are also completely covered in dermal denticles, tiny tooth-like structures coated in enamel.
  1. Ampullae of Lorenzini, while sounding more like a main course in Pizza Express, is actually the name given to the hundreds of gel-filled pores covering a shark’s head. The pores help detect electrical signals given off by prey, and help sharks navigate their way through the ocean.

    If you look closely, you can spot this shark's ampullae of Lorenzini (BBC) 

    If you look closely, you can spot this shark’s ampullae of Lorenzini (BBC)

  1. The epaulette shark lives in the shallow waters of coral reefs and is an all-round magic little creature. It can use its fins like legs, enabling it to walk out of danger when the tide goes out, and its ability to live without oxygen for 60 times the length a human can is currently helping scientists in their studies on stroke victims.
  1. There are 600 species of ray, the flatter cousins of the shark. Mobula rays can be spotted off the coast of New Mexico, leaping out of the water in an apparent attempt to attract a mate. Giant manta rays, meanwhile, can grow up to seven metres across.
  1. Sharks go to nursery. Or at least juvenile lemon sharks do. They spend up to seven years growing up and learning from each other in a “nursery” in the shallow waters of a mangrove or coral reef.

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