Did you know? Yawning is common among social animals. Contagious yawning (yawning when someone else yawns–or while reading this post!) appears to coordinate behavior. source

Want to know more? See how long you can go without yawning while watching this Yawn-o-Meter video.

Did you know? Sinkholes are created when water flows through certain kinds of rock, dissolving the rock and carrying it away. This creates an underground cavern. When the ceiling gives way, it creates a sinkhole. source

Want to know more? Learn about how scientists study caves to understand their secrets at Science News for Students.

Did you know? The brilliant blue on these spider’s hind ends is created by teeny-tiny nanostructures on the scale-like hairs located there. source

Want to know more? Find out how peacock spiders’ colors create an optical illusion at National Geographic.

Did you know? Although many eels live in the ocean, electric eels are freshwater fish. They live in rivers throughout South America. source

Want to know more? The new species of electric eels are the first ones discovered in more than 250 years. Learn more at Science News for Students.

Did you know? Some spiders nurse their young with “milk” just like mammals do! Who knew these amazing creepy-crawlies were such good moms? source

Want to know more? Slingshot spiders can out-accelerate a cheetah. Find out just how fast they are at Science News for Students.

Scientists discovered this remarkable creature, called a siphonophore, while exploring the ocean floor with a submarine.

Although it looks a bit like a sawfish, it’s actually a relative of corals and jellies. Like its cnidarian cousins, the siphonophore sports a gelatinous body and stinging cells that it uses to take down prey, such as fish.

What sets siphonophores apart from their relatives is their structure. Rather than having a single body with different organs to do particular tasks, siphonophores are actually colonies of individuals. The specialized individuals work together to perform basic body functions–much like our organs do.

The fringe dangling along the side of the critter are its tentacles, equipped with stinging cells. Such tentacles are similar to (but much shorter than) those found on the Portuguese man-of-war. The best known siphonophore, the Portuguese man-of-war uses its sail to drift along the ocean surface, dragging its long tentacles through the water. Winds can blow them onto beaches, where people can receive nasty stings.

Did you know? Siphonophores are some of the longest animals in the world, measuring a whopping 40 meters (131 feet) in length. source

Want to know more?
Check out this exciting video of the creature’s first moments on film.

Researchers Katherine and Tim Krynak weren’t looking for shape-shifters. In fact, their discovery was a complete accident. They spotted a tiny, spike-covered frog they hadn’t seen before and took it to the lab to photograph. But when they placed the critter on a smooth surface, the spikes disappeared. When they returned it to a mossy enclosure (thinking they had picked up the wrong frog), the spikes came back. “We simply couldn’t believe our eyes, our frog changed skin texture!” says Katherine Krynak.

The change in skin texture allows the frog to blend in better with its environment. Many animals use some form of camouflage to hide from predators, and some, such as squid and chameleons, even change colors. But this is the first time scientists have found a frog that could change its skin texture to enhance that camouflage. The species is new to science, but the scientists say it has a close relative that shares the shape-shifting ability. However, no one had noticed the changes in skin texture before the discovery of the new frog.

Did you know? Some octopods (a term that means “eight legs”) change not only color, but also their body posture to make themselves look like venomous animals, including lionfish and sea snakes. source

Want to know more? Check out the Exploratorium’s page on camouflage in frogs.

The world’s biggest freshwater fish. And it’s no ordinary fish, it’s a giant freshwater stingray, also known as a freshwater whipray.

The ray was captured in Thailand’s Mae Klong River last week.

Rays and their shark relatives are cartilaginous fishes. That means they don’t have hard bones like we do. Instead their skeleton is made of flexible cartilage (feel your upper ear or the tip of your nose–that’s what shark and ray bones are made of).

Rays are gentle creatures that spend much of their time buried in sand. They use their stinging spines only when threatened (such as if you step on one).

Did you know? Many stingray species communicate by sending electrical impulses through the water. Other rays detect the pulses using pores lining the underside of the body.

Want to know more? Check out the Animal Diversity Web page on freshwater whiprays.