From the Desk of Dan Ashe

Celebrating Sharks for Shark Week

In honor of Shark Week, airing on Discovery Channel, we’re sharing 10 of our favorite facts about sharks!

1. There are over 500 species of sharks in the world.
And counting! The Smithsonian estimates there are over 500 species of sharks, grouped into 9 orders. Shark species are continuing to be discovered today as scientists continue to explore the ocean and dive deeper into shark research. Their fossil records date back to more than 400 million years ago, and based on these fossils, more than 2,000 species of shark have been described.

2. They play a vital role in marine ecosystems!
Sharks are the top predator in our oceans environment. As the National Aquarium notes, this might incite fear in humans when they think of sharks. However, without sharks, the natural order and balance of our coastal communities would be thrown off. Sharks play a vital role in our oceans ecosystem by ensuring species biodiversity and serve as indicators for the ocean health.

3. How big can a shark get?
Sharks come in a variety of sizes. The largest species is the whale shark, which can reach lengths of nearly 40 feet, with the largest reaching 61 feet, according to the Georgia Aquarium. Meanwhile, the dwarf lantern shark is just six inches long, and can fit in the palm of your hand. A shark’s size can be advantageous to surviving in its environment. For example; if they need to hide from bigger sharks in coral reefs they may be slim and small, versus if they stalk their prey in the open ocean, they may be big and agile.

4. Sharks can grow 50,000 teeth in their lifetime.
And not all look scary! Some bottom-dwelling sharks have flat teeth to break apart crustaceans, while others, like the whale shark, lack any teeth at all. Those sharks that have jaws with rows of teeth will lose them periodically. Since shark teeth aren’t deeply rooted like human teeth, when sharks periodically lose a tooth, a new one is ready to take its place.  Sharks can lose up to 30,000 teeth in a lifetime, according to the National Aquarium!

5. Sharks don’t have typical fish scales.
They have “dermal denticles.” Unlike normal fish scales, these special scales are called placoid scales that cover sharks from nose to tail. They allow sharks to be more quick and agile in the water, decrease drag and turbulence, and allow sharks to swim faster and more quietly. Learn more at New England Aquarium.

6. Sharks have a special "Sixth Sense."
They have a special sensory organ called the Ampullae of Lorenzini.  This special organ has electroreceptors that form a network of jelly-filled pores that allow sharks to detect prey from long distances, SeaWorld explains. The movement of prey creates an electrical field that sharks can sense and then navigate towards to begin their hunt.

7. Sharks don’t sleep or blink.  
Some species of sharks must continue to swim in order to keep oxygen flowing through their gills to breathe. So, instead of stopping somewhere to get some sleep, sharks remain semi-conscious. Sharks can’t even close their eyes or blink, because their eyelids don’t move, explains Adventure Aquarium. Instead, they can protect their eyes with a third eyelid called a nictitating membrane.

8. Sharks don’t really need that much food.
Sharks eat at one to two day intervals, according to North Carolina Aquariums, because they expend such little energy when cruising through water at about 5 miles per hour. A satiated shark may not eat for several weeks. Some sharks, like the whale shark and basking sharks, feed exclusively on tiny fish and plankton.

9. Shark attacks are rare.
You are more likely to be struck by lightning or killed by a tornado than you are to be attacked by a shark, says Shedd Aquarium. When shark bites occur, it is most likely for one of the following reasons: the shark has mistaken the shape of a human for a seal; the shark is curious and trying to determine if what it’s seeing is food; or the shark has been provoked, says National Aquarium. Like most animals, sharks try to avoid people.

10. Humans are sharks' biggest threat.
Humans are the leading cause for the rapid decline in shark populations, says Wildlife Conservation Society. Climate change and unsustainable or illegal fishing practices such as overfishing, bycatch, and shark finning, leave shark populations facing hard times. This makes it difficult for their populations to stay at a sustainable level. Luckily, AZA members like Mote Marine Laboratory and Aquarium’s Sharks and Rays Conservation Research Program are promoting science-based conservation of depleted shark populations.

How are AZA-accredited facilities helping to save sharks?
Of the 500+ species of sharks, 74 species are classified as globally threatened and 26 of these are classified as Critically Endangered or Endangered. Since 2013, more than 50 AZA-accredited facilities contributed to shark and ray research to help conserve this misunderstood species. More than a dozen AZA-accredited facilities continue to use research and education to reverse negative public perceptions of sharks. Sharks and rays are also a part of the Species Survival Plan® program that continues to streamline and standardize data collection and banking of biological information for sharks and rays in human care. We continue to contribute time and resources to make sure this species has a fighting chance for the future.

Posted by Ashley Jones at 12:00 PM

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