9 Things You Didn't Know About Sharks

Out in the depths of the ocean, a school of fish circulates steadily one minute and scatters the next. Cue the Jaws theme music—that's right—it's almost Shark Week. [slideshow:1043]

The Discovery Channel started this weeklong celebration of recreated shark attacks and otherwise damning footage of the "super predator" in 1987 and it used to look a little different. The original idea behind the themed week was to teach people about sharks. Now, some say, the programs paint a twisted picture of sharks and perpetuate the stereotypes they once tried to refute.

Though the programs have made entertainment the top priority, Shark Week is still a great opportunity to highlight some of the cool facts, point out the misconceptions and make people aware of the threats facing sharks now. It is also a time to acknowledge there's still much we don't know about sharks. According to the IUCN Red List of Threatened Species, roughly 20 percent of all shark species are categorized as "data deficient," which means we don't have enough information to discern whether or not they are at risk for extinction.

From the information available, though, it's clear that humans are a major threat to sharks. There are currently more than 200 species of shark on the "Red List" of endangered species.

In a typical year, sharks kill an average of six people—humans, on the other hand, kill up to 273 million sharks by some estimates. Conservative assessments put the rate of killed sharks closer to 100 million a year, but the numbers are troubling either way. Sharks are sought after for their fins, meat and oil, and fishermen are eager to cash in on the trade.

In order to stop the decimation of shark populations, and to appreciate sharks in all their glory, people need to know the facts. We've put together a collection of things you might not know about sharks so you can be ahead of the curve during Shark Week.

There are more than 400 species of sharks

Ranging in size from just a few inches to more than 52 feet long, the 400+ species of sharks are as diverse as the oceanic ecosystem that is their home.

Sharks are colorblind

Sharks only have one type of cone photoreceptor, compared with our three cone photoreceptors, so they can only see in black and white. 

Click here to see more facts about sharks.

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