Sharks are pretty amazing.
There are over 500 known species of sharks in the world (counting extinct species, about 400 species today) living in all seven of the world’s oceans. Ithough sharks generally avoid fresh water, there are some sharks that live in fresh water and others that can live in brackish water too!
This may be because they have had a long time to evolve….and have not changed much in millions and millions of years because they are so well adapted.
Ever wonder how the world might have been like in the time of the dinosaurs? Well sharks are living history that have largely remained almost completely unchanged for the past 100 million years. The sharks that dinosaurs would have experienced are very similar to the sharks that we see today. Sharks first emerged around 400 million years ago, pre-dating dinosaurs by 200 million years!
Sharks come in all sizes from whale sharks, which at up to 60 feet long is the largest shark species and also the largest species of fish in the world, to pygmy lantern shark, which is only 8 inches. The two biggest species of sharks – whale sharks and basking sharks – are gentle giants that feed on plankton.
Because cartiledge is lighter and more durable than bone, shark skeletons are made of cartiledge. Their jaws are not attached to the skull, which allows it to move seperately and lunge forward to latch onto prey. While sharks generally have about 45-50 teeth, that’s actually only the “front row” of teeth. They have multiple rows of teeth so when one breaks off or gets damaged, replacement teeth moves forward. A shark may go through as many as 30,000 teeth in its lifetime!
Sharks need to keep moving to breath and consequently, they never actually enter a true-state of sleep. Swimming is coordinated by their spinal cord rather than their brain and some species of sharks can “sleep-swim”!
Sharks have super senses. Their noses are not for breathing, just for smelling and they can detect blood at one part per million. Additionally, they also have great eyesight even in lowlight settings due to a mirror like layer at the back of the eye. Though it is not visible, sharks also have ears and can detect sounds over 800 ft away. To top it off, sharks can also detect electricity with electroreceptors in their snout called “ampullae of Lorenzini”, which they use to detect electromagnetic fields that all living creatures emit!
Sharks are amazing, majestic creatures who are in much more danger from humans than we are from them. There is a lot of fear surrounding shark attacks but in general, they are very rare as the statistics from National Geographic show below:
- You have a 1 in 63 chance of dying from the flu and a 1 in 11 million chance of being killed by a shark during your lifetime.
- Over 17,000 people die from falls each year. That’s a 1 in 218 chance over your lifetime, compared to a 1 in 11 million chance of being killed by a shark.
- In 1996, toilets injured 43,000 Americans a year. Sharks injured 13.
- In 1996, buckets and pails injured almost 11,000 Americans. Sharks injured 13.
- In 1996, 2,600 Americans were injured by room fresheners. Sharks injured 13.
- Only five people die from shark attacks yearly, while millions of people die from starvation.
- For every human killed by a shark, humans kill approximately two million sharks.