Many organisms dedicate their entire adult lives to finding a mate and producing offspring. The rhythms of sex govern the actions and choices of so many animals that it seems to be a rule of biology: Sex is important.

But life’s multifariousness yields some exceptions. A small percentage of animals reproduce asexually, though many of these also resort to sex now and then. These asexual outliers have different techniques for reproducing: Some small invertebrates create offspring by budding, growing small versions of themselves that eventually detach; others, like some corals, can divide themselves in two. Some fish species need males around only because they require sperm to kickstart their reproductive process, even though they only rarely incorporate any genetic material from those males.

What’s black, white and showing up in two Georgia counties?

If you guessed Argentine black and white tegu lizards, you’re probably either a herpetologist or a resident of the Peach State who has helped wildlife officials track and trap these invasive reptiles.

Argentine tegus, which can reach lengths of up to 4 feet when fully grown, are not native to Georgia. As their name suggests, they’re originally from South America, found in Argentina, Brazil, Paraguay and Uruguay. Like many other invasive species — reptiles in particular — they have ended up far from home thanks to people wanting to keep them as pets. Then they’re either accidentally or intentionally released into the wild.

As you get closer to Earth’s poles, seasonal swings in temperature and vegetation get increasingly drastic. In many places, snowy winter wastelands alternate with relatively lush summers. That can make life hard for birds, unless they can cope with the weather — and their food sources — changing throughout the year. Birds that can’t handle it migrate to warmer climes for the winter. Those that tough it out year-round tend to have big brains relative to their body size, which help them figure out how to manage life in the changing landscape — or so scientists had thought.

Atlantis: the legendary island that sank beneath the waves in the distant past, taking down with it an advanced civilization. Is it possible that we will ever find it? Or, more importantly: Did it even exist?

The short answer to both: No. All available evidence indicates that the philosopher Plato, sometime around 360 BCE, invented the island nation in order to illustrate a point about the dangers of aggressive imperialism. In Plato’s telling, Atlantis was no utopia. Rather, it was a foil for an idealized version of Athens from long before Plato’s time. This ancient Athens “was very similar to Plato’s notion of the ideal state,” says Jyl Gentzler, a professor of philosophy at Amherst College. Plato laid out the details for what such a state would look like in his famous work, The Republic. According to Gentzler, it should be small and virtuous, and reject ostentation. The residents of Atlantis, on the other hand, were eventually “filled with an unjust lust for possessions and power,” according to Plato’s character who described the island.

The propeller plane passed through thick clouds, twisting and dipping in the wind like a toy on a string. Its flight to Montserrat—a small volcanic island in a chain of more than a dozen Caribbean territories and nations that curves from Puerto Rico to South America—was just 20 minutes. For 28 of the plane’s occupants, though, it was the culmination of 30 hours of travel from Europe, plus a decade of labor. The pilot and the plane’s lone human passenger, Luke Jones, sat in seats up front; the 28 crouched on shredded paper, each within a cloth bag nested inside one of six wooden crates. If any of those 28 frogs called out in instinctive recognition of their ancestral home, it would have been impossible to hear over the engines’ roar. But when the plane landed and the engines shut off, the animals were deathly silent.

Descending a few dozen feet into the open pit mine, visitors enter a monochromatic world that looks like a desert planet from Star Wars. On all sides, walls of nearly pure quartz sandstone rise up, the sparkly tan of raw cane sugar, layered with bands of different shades. Loose sand sits in small piles at the base of the cliffs; in the distance, larger piles are being loaded into huge yellow dump trucks that can move 70 tons of the stuff at a time.

But they’re not digging for valuable ores or precious metals buried beneath all this sand. This is a sand mine, and there are dozens like it in western Wisconsin. This state, and others in the Midwest, have some of the best sand in the world.

Ben Goldfarb answers questions about his book Eager: The Surprising, Secret Life of Beavers and Why They Matter (Chelsea Green, 2018).

PÁTZCUARO, MEXICO — Atop the highest hill in this lakeside town sits the Basílica de Nuestra Señora de la Salud, built in the 1500s with whitewashed walls and red stone columns.

On a street around the corner from the basilica, a wooden door framed in carved stone and marked with a cross fleury stands open from 9 a.m. until 2 p.m., and again from 4 p.m. to 6 p.m. “We pray for you,” reads a sign on the door in Spanish.

Inside, the room is sparse and dark save for a wooden window and three locked doors. Behind them is a convent, home to two dozen nuns of the Dominican Order.

But the convent also hosts an even larger number of very unexpected residents: a thriving colony of endangered salamanders. Scientists call them Ambystoma dumerilii, but the nuns and everyone else in Pátzcuaro call them achoques. [Photograph by Adriana Zehbrauskas]

Hidden away in the woods near the upstate New York town of Lake George is a cave. The entrance of the cavern, an abandoned graphite mine, is almost perfectly round, with a trickle of water running out of it. On a weekday morning in late February, researchers, led by Carl Herzog, a wildlife biologist for the New York State Department of Environmental Conservation, gather at the cave mouth and swap hiking boots for waders before filing in.

On a drizzly December afternoon in western Massachusetts, U.S. Geological Survey wildlife biologists Evan Grant and Adrianne Brand stop their car on the side of the road and plod into the wet forest through a break in the oaks and white pines. It’s a bit late in the year to find the predators they’re searching for, but this forest is teeming with them. In fact, as soon as they walk past the first tree, they’re probably never more than a few feet from one. You’d never know it, though.

A year ago when I arrived here by helicopter with researchers Colin Donihue and Anthony Herrel, this small Caribbean island was a moonscape. A mile long, Redonda is a rock nub protruding up from the sea; its steep, windy cliffs dropping into the sapphire water below.

Accounts from various explorers indicate that over the last century its surface had been gradually eaten bare of vegetation by invasive goats. Guano miners in the 1800s may have brought the animals as a source of fresh meat, although there’s mention of goats as early as 1745. The island we saw was also overrun with rats, likely survivors of shipwrecks, which would eat just about anything the goats didn’t—including at least two of the three species of lizards found only here.

The small propeller plane vibrates alarmingly as it takes off from the main airport in the Bahamas. It’s carrying unusual cargo: besides the eight human passengers, there’s a large white cooler, over three feet long. Inside, in dozens of round plastic deli containers, are 120 live lizards, collected over the previous days on another Bahamian island.

America has the highest salamander biodiversity of any country in the world. But that incredible natural heritage is threatened by a killer fungus that has already decimated salamander populations in Europe. Now, a dozen scientists who study amphibians and conservation are calling for a total ban on amphibian imports into the United States in an effort to prevent a mass die-off of our nation’s salamanders.

Even on his year off, Frederic Brewster Loomis could not escape the dead. 

The year was 1923, and this Amherst professor of geology, paleontology and biology—also a member of the class of 1896—was traveling south to Florida with his family, ostensibly “to enjoy the orange and grape fruit groves, the truck farms and sea beach.” But in Washington, D.C., the vacation morphed into a business trip when he visited the Smithsonian National Museum of Natural History. There he found a shipment of fossil reptiles from South Africa in need of a home. He promptly arranged for them to go to Amherst. 

Hilary Palevsky ’07 is the seafaring type. She spent part of her Ph.D. years in the North Pacific aboard a Chinese container ship, collecting data on dissolved oxygen levels in the ocean. Earlier she taught marine science to K–12 students on two-masted schooners in Long Island Sound. She also spent a year as a Watson Fellow talking to fishermen, scientists and policymakers about Atlantic cod fishing.

It’s a Friday morning during harvest season, which means that it’s market day at Barberry Hill Farm in Madison, Connecticut. And Kingsley Goddard, who has been running this farm since 1987, is not happy. His broccoli is crawling with bugs. The vegetables are soaking in a cooler full of icy, salted water in the back of his beat-up, white pickup truck. Goddard hopes to drown the small caterpillars and beetles on his produce. But he’s pragmatic about the outcome: “I didn’t get skunked, you know?” he says. “I still got broccoli.”

At most public swimming pools, you can be pretty sure you won’t encounter an endangered species while taking a dip. But not at Barton Springs Pool in Austin, Texas. Here, if you walk along the concrete edge and down the ramp into the clear, unchlorinated, chilly waters, and swim out to the pool’s far side, you may come face-to-face with a small salamander that was once called “one of the most endangered vertebrate species in North America.”

Stephen Durham ignores the cold water seeping into his hiking boots as he wades into a shallow, brackish creek wending through a salt marsh in Madison, Connecticut. With each step, shells crunch under his feet and he sentences a few more oysters to an early death. Below these casualties, the remains of their ancestors lie entombed in the muck. Less than a meter down, they could be hundreds of years old—artifacts of a time before modern record-keeping. Like thousands of soap-dish-sized Rosetta stones, the shells can reveal clues about the past—if you know what you’re looking for.

he flat light of dusk settles over a small meadow in western New York. Trills of tree frogs mingle with the songs of nearby catbirds and the occasional whine of a mosquito. The grass is tall on this warm July evening, in some spots rising over the head of Sarah Sander ’06. She’s in her full field regalia: headlamp, stopwatch, tall rubber boots and, most important, a collapsible white net with a 6-foot aluminum handle. Just before 9 p.m., she spots the first dim flickers of yellow light amongst low tree branches: fireflies.

Squirming at the bottom of the Ziploc bag is a small salamander, its olive-hued back dotted with rust-colored spots. Evan Grant peers closely at the captured creature, his bearded face just a few inches away from its bright peach belly, as he checks for any abnormalities. In particular, he's looking for skin lesions: possible omens of a coming salamander apocalypse.