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It's tough to be a fuzzy little mammal. Death can come from the sky or beneath the earth or behind the next tree, so their lives are governed by constant, quivering fear. Prey species live in a dangerous neighborhood, and they must always be alert to their surroundings. That's why a Middle Eastern plan to control pest populations with predatory birds is brilliant. Instead of pouring toxins on their crops to kill rodents, they are installing nest boxes for day-hunting kestrels and night-hunting barn owls to provide around-the-clock mouse munching.
While the kestrels and owls certainly do kill rodents directly, their very presence means that pest populations are reduced before they even lift a claw. Without predators around, the mice and insects stuff themselves all day long without fear. But once the prey know that they could get chomped at any moment, fear changes their behavior completely. They hide more, eat less, and have fewer babies. Even if they can get enough food, the incredible stress of being ready to flee at any moment reduces their lifespan. Past studies have shown that grasshoppers are so afraid of wolf spiders that they will starve to death in hiding rather than seeking food near the spider. And rabbit babies born to parents who are afraid of lynxes are less healthy than rabbit babies born to parents in lynx-free environments.
Fear can also change entire ecosystems. When wolves were reintroduced to Yellowstone, the fat, lazy elk were forced to run away instead of spending their days lounging by the river. Once the elk stopped overgrazing, willow trees were able to regrow near the water, creating bird habitat. Now that the willows have regrown, beavers might come back and dam up parts of the river, making homes for fish and wading birds. The wolves are killing relatively few elk, but the behavior of the entire population has changed.
I hope more farmers put out owl and raptor nest boxes—I'd much rather have my veggies taste of fear than of pesticides. And while bringing top predators like wolves and mountain lions back into densely populated areas is probably impractical, I think the fear that would induce might have other benefits. Can't you envision the popularity of the "How To Lose Ten Pounds By Hiding From Ravenous Beasts" diet?
Photograph of mouse by John Foxx/Getty Images.
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Don't you hate it when you accidentally have sex with your sister? This happens to Indian meal moths, a common kitchen pest that feeds on grains and cereals. Being moths, they don't really care about the moral issues, but offspring of an incestuous moth union are likely to be infertile. And since the moths have only a week get busy before heading off to the Great Pantry in the Sky, they can't afford too many reproductive dead ends.
But new research, published in this month's Animal Behavior, shows that male moths can stop worrying about fruitlessly spending their sperm on their sisters. Male Indian meal moths are tantric masters. If they're getting down with an unrelated lady friend, they give her ejaculate chock-filled with the very finest of sperm. But if they met their sweetie in the next cocoon over, they only release half as many sperm. That way, the moth isn't wasting energy on a whole Flowers in the Attic scene and can save his sperm for a less related lady.
While many female insects have a built-in morning-after pill that allows them to discard sperm they don't like, it was thought that male insects just had to thrust and think of England. But apparently even male moths yearn for control over the ultimate fate of their gametes. After all, when a single sperm can make the difference between being a grandpa moth or evolutionary roadkill, every sperm is indeed sacred.
Photograph of mating Indian Meal Moths by Richardus / Wikipedia.
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And you thought human sex was messy: A paper published in Science yesterday introduces the world to a bunch of tiny, ancient crustaceans that produced relatively massive sperm. And io9.com has pictures! (Don't worry; they're safe for work—and oddly beautiful.)
Researchers in Europe used cutting-edge "synchrotron X-ray holotomography" to non-invasively examine 100-million-year-old fossilized ostracods. The descendants of these millimeter-long creatures produce giant sperm—up to 10 times as big as their bodies, in some cases—and the new fossil images prove that their ancestors had the plumbing to do the same.
Giant sperm can give males a competitive edge when females end up mating with more than one partner; the trait is seen in some bird, insect, worm, and primate species, as well. Thankfully, humans never went down that evolutionary route: To match the aforementioned group of modern ostracods, our brothers would have to produce sperm nearly 56 feet long.
Of course, that's nothing compared to the humble fruit fly. Uncoiled, a Drosophila bifurca sperm measures almost 6 centimeters—or a little more than 130 feet, when scaled up to human size. Takashi Murakami would be proud. (Now, that's not SFW.)
