Doesn’t look a day over 40 million, right? This fossilized sperm and its compatriots turned up in a 50-million-year-old worm cocoon in Antarctica. And it has some pretty exciting implications for scientists—aside from the obvious news that we’re looking at a loser of an eons-old swimming race.
Ordinarily, squishy worms don’t wriggle into the fossil record. Their boneless bodies tend to disappear from history, just like the soft parts of animals with skeletons. That’s why scientists don’t know much about the evolution of clitellates, a class of creeping animals that includes earthworms and leeches. All they’ve left in the fossil record is a scattering of their hard egg cases, or cocoons. Read More
As much as you think your tastes are unique, psychologists say they can guess your favorite color. It’s likely to be blue. And it’s especially unlikely to be yellow—unless you’re colorblind. Men with red-green colorblindness have preferences that are essentially opposite from everyone else’s. The finding could help scientists understand why humans like what they like, and how colorblind people see the world differently.
Some researchers have claimed that the human love of blue is universal. Others have turned up different color preferences between cultures. Either way, studies in the United States and the United Kingdom have found that people with normal color vision tend to most enjoy the color blue, and to least like yellowish-greenish hues.
Universidad Complutense de Madrid graduate student Leticia Álvaro and her coauthors wanted to see how these preferences differ in colorblind people, or “dichromats.” Read More
What’s a tree worth to you? According to a large study in Toronto, trees may increase both how healthy you feel and how healthy you really are. Having some extra foliage on your block could be as good for your health as a pay raise–or an anti-aging machine.
It’s a complicated relationship to figure out, because variables that affect how many trees you see each day could also affect your health. The population of a concrete, inner-city apartment complex may have socioeconomic differences, for example, from the population of a leafy, well-tended suburb. University of Chicago psychologist Marc Berman and his colleagues used a detailed analysis to try to tease out the impact of trees themselves.
They started by going to Canada. In a country with universal health care, they figured, access to doctors isn’t as much of a variable as in the United States. Read More
If you already think everything at the bottom of the ocean is slightly terrifying, Iosactis vagabunda won’t change your mind. It’s transparent, can tunnel underground, and hunts animals 15 times its size. And scientists are now realizing that there might be way, way more of these roaming killers than they’d previously thought.
Iosactis vagabunda lives on the Porcupine Abyssal Plain, a seabed southwest of Ireland that ranges from 4,000 to nearly 5,000 meters deep. The species was already thought to be common in this area. But ocean-floor trawls don’t drag up many of the animals, thanks to their small, squishy bodies and tendency to burrow.
To learn what the transparent creatures are really doing down there, National Oceanography Centre graduate student Jennifer Durden and her coauthors used tens of thousands of photographs. Read More
When you look at a kangaroo or a wallaby, it’s obvious the animal is well built for bouncing around the outback. What may be less obvious is that its arms are built for fighting—if it’s male, that is. Males of these species have disproportionately long arm bones. And the more brawling a species does, the more exaggerated the difference between the beefy-armed males and their normal-limbed mates.
To understand this evolutionary quirk, we’ll need to review the rules of fighting in wallabies and kangaroos. (Together, these animals are called macropodids.)
Males wrestle each other to show their dominance and to gain access to females. The first rule of macropodid fight club is not “don’t talk about macropodid fight club,” but “kick a lot.” Read More
This month has accidentally taken on a theme of “animals putting things outside their bodies that we think should stay inside” (starfish tags, sea squirt stomachs). So this post, which first appeared in April 2013, seemed like the right one to wrap up with.
She’s apparently a picky mater but not a picky eater. The female of a certain fly species, after mating with a male, dumps his ejaculate back out of her body and onto the ground. Then she gobbles it up. Despite new hints that this behavior may help the female choose which partner fertilizes her eggs, or keep her healthy in times of famine, scientists are still a little perplexed by it.
Various female insects, spiders, and birds are known to expel the male ejaculate from their bodies after the deed is done. In some cases, it seems to let them decide which male’s sperm reaches their eggs. Females don’t always choose who mates with them, but that doesn’t mean they have no choice in their progeny’s fatherhood. (This kind of female choosiness about sperm can lead to evolutionary arms races between males and females. The “copulatory plug” is a popular tool among male insects, spiders, reptiles, and even some mammals.)
Eating the ejaculate, as Euxesta bilimeki does, is less popular. Read More
We may call someone gutless who’s acting afraid. But certain coral-reef dwellers take gutless to a whole other level: they shoot their digestive tracts out of their bodies when they feel threatened. This seems to deter nearby fish from taking a bite. Even more amazing, though, is how quickly the gutless animals grow back their organs.
Polycarpa mytiligera is a little tube-shaped creature called an ascidian, or sea squirt. It resides in tropical waters of the Indian and Pacific oceans. With its base glued firmly to a coral reef or other surface, it feeds by filtering particles from the passing current. Some sea squirts look like colorful vases arranged together on a reef. But Polycarpa mytiligera lives alone and lets other bits of sea life grow all over its body for camouflage.
Scientists first noticed in the 19th century that some sea squirts have no guts. The animals are known for regenerating missing body parts, so it seemed that they must occasionally lose their digestive organs and grow them back. But how and why remained a mystery. Read More
There’s good news for scientists who study animals that are too small to carry a GPS monitor, or that spit ID tags back out through their arms. A setup using an off-the-shelf camera can precisely capture an animal’s path in three dimensions—without anyone touching the animal.
Emmanuel de Margerie, who studies animal behavior at the University of Rennes 1 in France, says there are several reasons to seek new animal-tracking technologies. To put a GPS or other kind of tag on an animal, you have to capture and handle it, which can be stressful for your study subject. The tags themselves can be expensive and unreliable, and sometimes get lost. And “small species cannot be tagged at all because the tag is too heavy for walking or flying normally,” he says.
So de Margerie thought up a way to track animals purely by sight. He and his coauthors have dubbed it “rotational stereo videography” (RSV). It works like this: Read More
Scientists already knew starfish have superpowers. They can regenerate entire lost limbs or organs; some can even regrow a whole body from one arm. And these animals have just revealed another bizarre ability. To two Danish students, it first appeared as the power to really wreck an experiment.
At the University of Southern Denmark, students Frederik Ekholm Gaardsted Christensen and Trine Bottos Olsen were asked to tag some starfish. The task was simple: inject the Asterias rubens with microchips, the same kind that veterinarians implant in pet dogs. This would let researchers easily identify individual starfish later on. The technique had already been used successfully in sea urchins.
Starfish came to the university from local fishers who had caught them by accident. The students injected the tags into the animals as directed. But within days, those same tags showed up at the bottom of the tank. Somehow, the starfish were expelling the foreign objects from their bodies. Read More
How long could you survive as a tortoise? Sure, the basic rules are easy: Eat plants. Hide in your shell. Slow and steady wins the race. But a tortoise in danger has to make some quick decisions. Especially if it’s been flipped onto its back, slow and steady isn’t good enough. The tortoise’s best strategy, in fact, depends on its age.
Ana Golubović, a biologist at the University of Belgrade in Serbia, is interested in how the behavior of turtles and tortoises changes over their lifetimes. Baby tortoises are small and fairly soft. As they age, their shells harden and the reptiles grow—and grow, and grow. The older the tortoise, the bigger it is. (You can even estimate a tortoise’s age by counting rings on its shell, like a tree trunk.)
This means an adult tortoise can rely on its shell in ways that a younger one can’t. Golubović notes that not only do juveniles have softer shells, but they get no protection from their parents, and they’re bite-sized to some predators. So a young tortoise that gets attacked and flipped is more vulnerable than its better-armored elders are. Read More