A bat, flying through the night sky, is thirsty. As it flies, it sends out high-pitched squeaks and listens for the returning echoes. It hears a telltale pattern. It hears no echoes form up ahead and the only ones that reflect back at it are coming from straight below. That only happens when the bat flies over a flat, smooth surface like the top of a lake or pond. The bat dives, opens its mouth to take a sip of refreshing water… and gets a mouthful of metal.

In nature, bodies of water are the only large, smooth surfaces around. Waves of sound that hit the surface of still water would generally bounce away, except for those aimed straight downwards. Stefan Greif and Björn Siemers from the Max Planck Institute for Ornithology have found that bats are instinctively tuned to find water using this unique feature (and yes, the institute does mostly, but not exclusively, bird research).

The man-made world is full of surfaces with the same properties, including metal, plastic and varnished wood. When Greif and Siemers released bats over smooth plates made of these materials, the animals tried to drink from them. If the plates were textured with small ridges, the bats ignored them. This instinct seems common to echolocating bats, for Greif and Siemers tested 15 different species with varied lifestyles and distantly related families. All of them did the same thing. Read more

Not everyone has access to something as basic as clean water.

World Water Day was created to bring attention to the global water and sanitation crisis, and to inspire people the world over to take action. You may be wondering, “what crisis? I have all the water I need.” I’m talking about the fact that an estimated 663 million people still lack access to an improved drinking water source, and almost 2.4 billion lack a basic toilet. What’s more, every day almost 1,400 children around the world die from something as simple as diarrhea, which is mainly caused by unsafe water and poor sanitation and hygiene. Read more

Aliens are invading Antarctica. Thanks largely to scientists, they have already established a foothold on the frozen continent, and their numbers are set to increase. This might sound like the plot of John Carpenter’s classic film The Thing, but it is very real.

The aliens in question are not body-snatching monsters, but plants from other parts of the world. Steven Chown from Stellenbosch University found that in just one summer, visitors unwittingly imported around 70,000 seeds to Antarctica. And even though the continent has a reputation for being harsh and desolate, many of these immigrants have already founded populations in their new homes.

This is a new chapter in an old story. Wherever humans go, seeds hitch a lift on our clothes and belongings. If these foreigners germinate where they don’t belong, they can often out-compete native plants and uproot local ecosystems. From Japanese knotweed to kudzu vines, these invasive species cause problems throughout the world. Inhospitable though Antarctica is, it’s not immune to such invasions. It does, however, present a valuable opportunity to study them. Read more

Antarctica normally conjures images of white and blue, but the frozen continent can sometimes bear more unexpected colours. Take the Taylor Glacier – when geologist Griffith Taylor first explored it a century ago, he found a bizarre reddish stain that seemed to spill waterfall-like from the glacier’s snout. The area became evocatively known as Blood Falls. 

The source of the blood-red colour is an underground saltwater lake that was trapped by the encroaching glacier at least 1.5 million years ago. The temperature of the water is -5 Celsius, but it’s so salty that it doesn’t freeze. It’s also rich in iron salts, which are slowly leaching the ice – these are the source of the distinctive red hue. Blood Falls is a rust glacier.

But it also houses another secret, which scientists from Harvard University have started to uncover – it’s home to an entire ecosystem of bacteria, trapped for millennia in conditions that could hardly be more inhospitable to life. Read more

“This is what the end of the world looks like,” says Yusup Kamalov, sweeping his hand toward the scrub-covered desert stretching before us. “If we ever have Armageddon, the people of Karakalpakstan are the only ones who will survive, because we are already living it.”

For millennia the Aral Sea reigned as one of the planet’s largest inland bodies of water, straddling what is now Kazakhstan and Uzbekistan. Today its decline serves as a cautionary tale.

From our perch atop this sandy bluff in northern Uzbekistan, the view could be of just about any desert—that is, if it weren’t for the mounds of seashells and the half dozen marooned fishing boats rusting into the sand. This spot was once the tip of a peninsula jutting into the Aral Sea, which up until the 1960s was the world’s fourth largest inland body of water, covering some 26,000 square miles—an area larger than the state of West Virginia. Behind us lies the town of Muynoq, formerly a thriving fishing village with a sprawling cannery that even as recently as the 1980s processed thousands of tons of fish annually. Fifty years ago the southern shore of the Aral was right where we stand; now it lies 55 miles away to the northwest. Read more