Sunday, February 19, 2012
Sharks have a bad wrap for being huge, aggressive man eaters when the truth is that they have more reason to be afraid of humans than the other way around. Shark attacks are rare, deaths from attacks even more so at only about five per year. There are only a few species of sharks, out of over 440, that a known to be aggressive towards people - the great white shark (Carcharodon carcharias), the bull shark (Carcharhinus leucas), and the tiger shark (Galeocerdo cuvier).
On the other hand, humans kill over 70 million sharks every year. There is a large (and in some places illegal) market for shark fins to be used in soup. Many sharks are caught, have their fins cut off, and have their bodies tossed back in the ocean to die. Finning has been an increasing problem for shark populations. Since sharks are predators at the top of the food chain, their declining numbers have implications for the entire marine ecosystem.
Watch this public service announcement about a few of the ways you are more likely to die than from a shark attack.
Its too bad so many people are afraid of sharks because they are incredible fish. They have been around since dinosaurs roamed the planet and have survived that whole time without having any bones! Sharks are cartilaginous, that is they are completely made out of cartilage like that on your ears and tip of your nose.
The largest shark is the whale shark (Rhincodon typus). They average 30 feet long and 20,000 pounds, the largest on record was over 40 feet long and weighed over 47,000 pounds! Sound scary? Maybe a little, but not really when you learn that they are filter feeders and only eat small plankton and fish. They are docile creatures and swimming with them can sometimes be a tourist attraction when visiting their warm tropical homes.
Most sharks are much smaller than the whale sharks and great whites, some being less than a foot long. This little guy, known as a chain catshark or dogfish (Scyliorhinus retifer), is a small species that grows to about a foot long. This one is a guest at the New England Aquarium. Special thanks to Jack Szczepanski, graduate student at the University of Rhode Island, for helping identify his species.
You can learn more about sharks during the Discovery Channel’s annual Shark Week. There are a bunch of online resources.
Photos by Sara MacSorley