Shark Week: Interesting Facts About Sharks!


Photo: Wikipedia, CC

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With Discovery's Shark Week almost over, now is a good time to look back on some of what we've learned this week, and to learn a few facts about these magnificent ocean predators. (Yes, those little waves when a triangle above are supposed to be water and a shark fin. ASCII art at its finest!)


Photo: Flickr, CC

Sharks by the Numbers

Sharks appeared on the fossil scene about 455 to 425 million years ago (source).

There are about 440 species of sharks. (source)

They vary enormously in size from one species to the next. The dwarf lanternshark is around 6 inches long while the whale shark can reach 40 feet in length and weight almost 80,000lbs.


Photo: Flickr, CC

Sharks are found in all corners of the world's oceans up to depths of 6,600 feet (2 kilometers).

Shark lose their teeth, which are replaced by new ones. A single shark can lose over 30,000 teeth over its lifetime. (source)

Sharks have an exceptional sense of smell. Some species are able to detect blood in water in quantities as small as 1 part per million, and from distances as far as a quarter mile. (source)

It is estimated that up to 100 million sharks are killed by people every year, due to commercial and recreational fishing. Meanwhile, the "average number of fatalities worldwide per year between 2001 and 2006 from unprovoked shark attacks is 4.3".


Photo: Wikipedia, CC

The Horrors of Shark Finning

Sharks might be top predators in the oceans, but unfortunately for them, they aren't at the top of the pyramid on the planet. The impact of humans on sharks is the first thing to understand when looking at why shark populations are under pressure and declining over time. And because they are top predators, they've evolved to mature and reproduce slowly, so unlike other species, they can't be expected to bounce back quickly even if we could leave them alone for a while.


Photo: Public domain

Shark finning is the practice if catching sharks, cutting their fins and throwing them back in the water to die slowly. Finning is responsible for the death of between 73 million to 100 million sharks every year, as Jaymi reports in her post about shark finning.

Why are sharks being finned? Because shark fin soup is popular in certain asian countries, and the market value of the fins ($300/lbs in 2009) is much higher than the market value of the rest of the sharks, so it's more economical to simply bring back the fins to ground.


Photo: Flickr, CC

According to Shark Savers, "Life within the oceans, covering 2/3rds of our planet, has enjoyed a relationship with sharks for about 450 million years. Our growing demand for shark fin soup has increased the slaughter of sharks to such a great extent that many shark species are already nearing extinction. They may be all gone within only 10 or 20 years." (emphasis mine)

There is a little movement in the right direction, such as Taiwan tightening laws against shark finning, but much more needs to be done. Thankfully, new tools such as DNA identification can help in the fight for sharks' survival.

Check out Jaymi's post on 4 technologies that can help protect sharks.


Photo: Flickr, CC

Protecting Shark Habitat

One way to help protect sharks is to create sanctuaries for them. A huge one is under development in Micronesia. When completed, it will be 2 million square miles, about 2/3 of the size of the United States!

Blythe has a great post about 7 key shark habitats that need our protection.


Photo: Flickr, CC


Photo: Flickr, CC

Check out our slideshow of the 8 most endangered shark species.

For more shark photos, check out the sharks that are swimming around the TreeHugger Flickr pool.


Photo: Flickr, CC

If you like this article, you can follow me on Twitter (@Michael_GR) and Stumbleupon (THMike). Thanks.

More on Shark Week
Shark Week: Win A Date With Your Favorite Ocean Celebrity
Shark Week: An Explanation of Shark Finning
Shark Week and Biomimicry: Four Futuristic Technologies Inspired By Sharks
Shark Week: Demon Fish Dissects Sharks' History, Future, and "The Greatest Scam of All Time" (Book Review)
Shark Week: Four Unique Technologies Saving Sharks from Extinction
Shark Week: Electronic Shark Shield to Help Keep Swimmer Safe During Record-Setting Attempt
Shark Week: 8 of TreeHugger's Favorite Crazy, Cool and Bizarre Shark Stories

Tags: Animals | Oceans