Barry Peters via Flickr // CC BY 2.0
Barry Peters via Flickr // CC BY 2.0

10 Stunning Facts About Stingrays

Barry Peters via Flickr // CC BY 2.0
Barry Peters via Flickr // CC BY 2.0

If you’re unsure about your stance on stingrays, we don’t blame you. They’re often portrayed as deadly, cold-blooded creatures who wield their venomous tails like a murder weapon. They're also oddly adorable. The best way to form an opinion is by learning a little more about the mysterious stingray. Here are 10 facts about these saucer-like creatures of the deep.

1. STINGRAYS ARE FISH. 

Roberto Machado Noavia Getty Images

Though they may not resemble the finned friends in your fish tank at home, stingrays belong to a group of fish called elasmobranchs. There are around 200 different stingray species in total.

2. STINGRAYS ARE CLOSELY RELATED TO SHARKS.

Qldian via iStock

Stingrays and sharks belong to the same group of cartilaginous fish. This means that instead of bones, they’re supported by skeletons of cartilage. Like sharks, stingrays use sensors called ampullae of Lorenzini to sense the electrical signals emitted by their prey. These sensors are located around their mouths, and they compensate for the stingray's poorly-placed eyes.

3. STINGRAYS HAVE BEEN AROUND FOR A LONG TIME.

Kyle Durigan via Flickr // CC BY-NC-ND 2.0

Fossil records of the first rays date back to the Lower Jurassic Period (about 150 million years ago). By the Paleocene Era just 100 million years later, all major taxa of rays had been established. Stingray fossils are hard to come by due to their lack of bones, and some of the only evidence they’ve left behind are scales and teeth. 

4. STINGRAY VENOM WAS USED AS AN ANESTHETIC.

Amit Chattopadhyayvia Wikimedia Commons // CC BY 2.0 


While painful, stingray venom isn’t usually deadly unless victims are stung in the chest or abdomen. In ancient Greece, venom was actually extracted from stingray spines for the purpose of being used as an anesthetic by dentists.

5. THE BIGGEST STINGRAY WEIGHS NEARLY 800 POUNDS.

Acquarious Sea Tours via Flickr // CC BY-NC-ND 2.0

Short-tailed stingrays, known as Dasyatis brevicaudata, are found off the southern coasts of Africa and Australia. They can reach 770 pounds in weight and grow 14 feet in length. The giant freshwater stingray (Himantura chaophraya) grows to be quite monstrous as well. In March, fisherman in Thailand’s Mae Klong River caught a 14-foot stingray that weighed between 600 and 800 pounds. It was one of the largest freshwater fish ever captured.

6. STINGRAYS AREN'T NORMALLY AGGRESSIVE. 

Elena Kalis via Flickr //CC BY-NC-ND 2.0

While a run-in with a stingray has the potential to be deadly, they normally act kind and gentle around humans. It’s only when a stingray feels threatened that divers have a reason to worry. Most stingrays attack when a diver is swimming directly over or in front of a ray, blocking its escape route. Accidentally stepping on a ray in shallow water is also a fast way to get stung. Expert divers shuffle their feet when entering the ocean to avoid stepping directly on a stingray’s back.

7. STINGRAY JAWS CAN CRUSH MOLLUSK SHELLS.

VirtualWolf via Flickr // CC BY-SA 2.0

Even though they’re cartilaginous, stingray jaws are strong enough to crush rock-hard clam shells. The calcified cartilage in their jaws is several layers thick, and the softer cores of their jaw elements are supported by hollow, mineralized struts. This makes stingray jaws strong and lightweight at the same time.

8. SOME STINGRAYS MOVE LIKE A WAVE, OTHERS LIKE A BIRD.

SnapperCR29 via Flicker// CC BY-NC-ND 2.0

Most stingrays swim through the ocean by undulating their bodies in a wave-like motion. Others will flap their sides up and down, giving them the appearance of “flying” through the ocean like a bird.

9. STINGRAYS ARE GOOD AT HIDING.

Jeff Kraus via Flickr// CC BY-NC 2.0

Next time you go for a walk through the ocean’s shallow waters, remember that stingrays spend most of their time hiding in the sand. Their mottled skin, ranging from a light sandy tone to a dark brown, gives them the perfect camouflage for chilling out on the sea floor until a tasty meal comes their way. It also keeps them hidden from predators of their own like killer whales and hammerhead sharks. To add an extra element of protection, stingrays will stir up sand with their wings while burying themselves head-first.

10. STINGRAYS ARE BORN FULLY-FORMED.

Little Peppercorn via Flickr // CC BY-NC-ND 2.0

When baby stingrays are born they look like miniature versions of their parents. They are fully-proportioned and naturally good swimmers from birth. This helps them find food on their own right away, though mothers still stick around to provide protection until around age three or so. Did we mention they also look like adorable raviolis?

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How Bats Protect Rare Books at This Portuguese Library
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Visit the Joanina Library at the University of Coimbra in Portugal at night and you might think the building has a bat problem. It's true that common pipistrelle bats live there, occupying the space behind the bookshelves by day and swooping beneath the arched ceilings and in and out of windows once the sun goes down, but they're not a problem. As Smithsonian reports, the bats play a vital role in preserving the institution's manuscripts, so librarians are in no hurry to get rid of them.

The bats that live in the library don't damage the books and, because they're nocturnal, they usually don't bother the human guests. The much bigger danger to the collection is the insect population. Many bug species are known to gnaw on paper, which could be disastrous for the library's rare items that date from before the 19th century. The bats act as a natural form of pest control: At night, they feast on the insects that would otherwise feast on library books.

The Joanina Library is famous for being one of the most architecturally stunning libraries on earth. It was constructed before 1725, but when exactly the bats arrived is unknown. Librarians can say for sure they've been flapping around the halls since at least the 1800s.

Though bats have no reason to go after the materials, there is one threat they pose to the interior: falling feces. Librarians protect against this by covering their 18th-century tables with fabric made from animal skin at night and cleaning the floors of guano every morning.

[h/t Smithsonian]

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Honey Bees Can Understand the Concept of Zero
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The concept of zero—less than one, nothing, nada—is deceptively complex. The first placeholder zero dates back to around 300 BCE, and the notion didn’t make its way to Western Europe until the 12th century. It takes children until preschool to wrap their brains around the concept. But scientists in Australia recently discovered a new animal capable of understanding zero: the honey bee. According to Vox, a new study finds that the insects can be taught the concept of nothing.

A few other animals can understand zero, according to current research. Dolphins, parrots, and monkeys can all understand the difference between something and nothing, but honey bees are the first insects proven to be able to do it.

The new study, published in the journal Science, finds that honey bees can rank quantities based on “greater than” and “less than,” and can understand that nothing is less than one.

Left: A photo of a bee choosing between images with black dots on them. Right: an illustration of a bee choosing the image with fewer dots
© Scarlett Howard & Aurore Avarguès-Weber

The researchers trained bees to identify images in the lab that showed the fewest number of elements (in this case, dots). If they chose the image with the fewest circles from a set, they received sweetened water, whereas if they chose another image, they received bitter quinine.

Once the insects got that concept down, the researchers introduced another challenge: The bees had to choose between a blank image and one with dots on it. More than 60 percent of the time, the insects were successfully able to extrapolate that if they needed to choose the fewest dots between an image with a few dots and an image with no dots at all, no dots was the correct answer. They could grasp the concept that nothing can still be a numerical quantity.

It’s not entirely surprising that bees are capable of such feats of intelligence. We already know that they can count, teach each other skills, communicate via the “waggle dance,” and think abstractly. This is just more evidence that bees are strikingly intelligent creatures, despite the fact that their insect brains look nothing like our own.

Considering how far apart bees and primates are on the evolutionary tree, and how different their brains are from ours—they have fewer than 1 million neurons, while we have about 86 billion—this finding raises a lot of new questions about the neural basis of understanding numbers, and will no doubt lead to further research on how the brain processes concepts like zero.

[h/t Vox]

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