CLOSE
Youtube
Youtube

This Wasp Turns Spiders Into Zombie Construction Workers

Youtube
Youtube

In another post, we were talking about what happens to spiders and their webs when scientists give them a little bit of marijuana and other drugs. While researching that post, I learned that it's not just humans that alter spiders’ behavior with chemicals. There’s a wasp in Costa Rica that does the same thing, in a more gruesome and sinister way, as part of its journey to adulthood. 

The tropical wasp species Hymenoepimecis argyraphaga is a parasite, and it takes advantage of an unlikely host. The web of the orb weaver spider Plesiometa argyra is normally a place where bugs meet their untimely death and become spider snacks. Using an arsenal of toxins and mind-altering chemicals, though, H. argyraphaga is able to turn the spider into a slave and a meal, and its web into a safe haven.  

When the female wasp is ready to lay her egg, she seeks out a spider to help raise her child. She stings the spider to paralyze it and then lays an egg on its abdomen. Soon, the egg hatches and the larva that emerges remains attached to the spider, living on its abdomen and sucking hemolymph (kind of the arthropod version of blood) from its body for nourishment. After a few weeks like this, during which the spider goes about its life as normal, the wasp larva is ready to move on to the next stage of its life cycle. To do this, it needs to make a cocoon. A spider’s web is a decent place to build one, but not perfect. It’s suspended above the ground and the sticky threads provide defense from predators that might eat the wasp, but it’s far too flimsy to support the heavy cocoon and the adult wasp that will come out of it. 

The wasp gets around this problem by forcing the spider to build a web that suits its needs. It injects a chemical (which hasn’t been identified yet) into the spider that alters the host’s behavior. The spider begins building its web as normal, but instead of completing all the steps and getting a carefully-patterned web, the zombified spider simply repeats the first few steps over and over again, resulting in a web that’s just a few heavily-reinforced anchor threads and a small center section. 

Once the web is done, the spider crawls to the center of the web and sits there complacently. The larva molts, kills the only companion it has ever known, sucks any remaining useful bits out from its corpse, and discards it. Then, it builds its cocoon on a web custom-built for the job. A few weeks later, the adult wasp emerges and flies away, and the cycle starts over. 

For more on parasitic wasps, see any of Carl Zimmer’s paeans to the Emerald Cockroach Wasp. 

nextArticle.image_alt|e
iStock
arrow
Animals
Slow Motion Is the Only Way to Appreciate a Chameleon’s Lightning-Fast Tongue
iStock
iStock

From the unusual way they walk, to their ability to change color, the evolutionary adaptations of chameleons are pretty bizarre, and some of them remain mysterious even to scientists. Their super-powered tongues, for instance, can dart out so quickly that the movement can barely be seen with the naked eye. But modern high-speed cameras have enabled researchers at the University of South Dakota to observe this appendage at work like never before. The video below, shared over at The Kid Should See This, includes some of that groundbreaking footage, and it's pretty amazing to watch.

Shooting at 3000 frames per second, the camera was able to capture every split-second aspect of the chameleon's tongue strike. Slowed down, the video allows you to see how every component of the process works in harmony: First, muscles in the lizard’s tongue contract like the string of a bow. Then, when that tension is released, the bony base of the tongue shoots forward, pushing the sticky, elastic part toward the chameleon’s prey.

According to Christopher Anderson, one of the scientists who conducted the high-speed camera research, larger chameleons can catapult their tongues forward at distances of one to two times their body length. For smaller chameleons, this distance can reach up to two and a half times their body length. “Small chameleons need to be able to eat more food for their body size than large chameleons,” he tells bioGraphic in the video, “and so by being able to project their tongues proportionately further than these large species, they basically are opening up additional feeding opportunities to themselves that they wouldn’t have if they had a shorter tongue.”

To see one of nature’s greatest hunting tools in action, check out the full video below.

[h/t The Kid Should See This]

nextArticle.image_alt|e
iStock
arrow
science
There May Be an Ancient Reason Why Your Dog Eats Poop
iStock
iStock

Dogs aren't known for their picky taste in food, but some pups go beyond the normal trash hunting and start rooting around in poop, whether it be their own or a friend's. Just why dogs exhibit this behavior is a scientific mystery. Only some dogs do it, and researchers aren't quite sure where the impulse comes from. But if your dog is a poop eater, it's nearly impossible to steer them away from their favorite feces.

A new study in the journal Veterinary Medicine and Science, spotted by The Washington Post, presents a new theory for what scientists call "canine conspecific coprophagy," or dogs eating dog poop.

In online surveys about domestic dogs' poop-eating habits completed by thousands of pet owners, the researchers found no link between eating poop and a dog's sex, house training, compulsive behavior, or the style of mothering they received as puppies. However, they did find one common link between the poop eaters. Most tended to eat only poop that was less than two days old. According to their data, 85 percent of poop-eaters only go for the fresh stuff.

That timeline is important because it tracks with the lifespan of parasites. And this led the researchers to the following hypothesis: that eating poop is a holdover behavior from domestic dogs' ancestors, who may have had a decent reason to tuck into their friends' poop.

Since their poop has a high chance of containing intestinal parasites, wolves poop far from their dens. But if a sick wolf doesn't quite make it out of the den in time, they might do their business too close to home. A healthier wolf might eat this poop, but the parasite eggs wouldn't have hatched within the first day or two of the feces being dropped. Thus, the healthy wolf would carry the risk of infection away from the den, depositing the eggs they had consumed away in their own, subsequent bowel movements at an appropriate distance before the eggs had the chance to hatch into larvae and transmit the parasite to the pack.

Domestic dogs may just be enacting this behavior instinctively—only for them, there isn't as much danger of them picking up a parasite at home. However, the theory isn't foolproof. The surveys also found that so-called "greedy eaters" were more likely to eat feces than dogs who aren't quite so intense about food. So yes, it could still be about a poop-loving palate.

But really, it's much more pleasant to think about the behavior as a parasite-protection measure than our best pals foraging for a delicious fecal snack. 

[h/t The Washington Post]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios