Shark week is coming to an end, and to cap off this wonderful week, we’re giving you enough shark facts to last you the whole year!
Sharks have roamed the oceans since well before the days of the dinosaurs and remain among the world’s most effective hunters.
Sharks originated some 450 million years ago, and many species have changed little in the past 100 million years.
Unlike most fishes, they have no gas bladder to keep them afloat, so many species must move constantly to keep from sinking.
Their skeletons are made of light, tough cartilage instead of bone, and many have large, oil-filled livers that make them more buoyant.
Sharks’ mouths bristle with rows of teeth which are constantly replaced by new ones as they become broken or worn.
The first vertebrates to develop an immune system, sharks may have greater immunity to cancer than humans, and they are being studied for potential new cancer medications and antibiotics.
Most sharks are no more dangerous than other fishes. Humans, however, have proved extremely dangerous to sharks.
Of the roughly 340 species of sharks, most never attack people. Fewer than 100 people per year are bitten by sharks, and less than 15 percent of these attacks are fatal.
Humans kill 50 to 100 million sharks each year, placing entire populations and some species at serious risk.
As top ocean predators, sharks maintain the balance of other populations.
Growing consumption of shark meat and fins, and the popularity of shark fishing for sport, have caused some shark species to decline by more than 90 percent, threatening the sharks’ survival and disrupting ocean ecosystems.
Some sharks lay eggs, but most bear live young, as mammals do. Some species remain pregnant for over two years – longer than any other vertebrate.
Sharks typically bear just three to 12 pups, and many do not reproduce until age 30, making it hard for them to recover when millions are killed by humans.
