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These Ants Use Mercenaries to Fight for Them

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In the jungles of Panama, a group of farmers ekes out a living by raising fungi for food. They’re peaceful, and when more aggressive neighbors come into their territory, looking for a cut of the crop, they oblige the guests and don’t fight them. While inconvenient, the arrangement pays off sometimes. When even more aggressive outsiders try to take over the farms, the first group of intruders earns their keep by repelling them and protecting their hosts. The not-exactly-welcome guests have their uses, and for the farmers, sharing a little fungus is a small price to pay for protection.

Humans have been using hired brutes to do their fighting for them for ages. Think of Blackwater Security, or Murder Inc., or Westeros’ most charming sellsword. But while the drama playing out in Central America echoes elements of Medieval history and The Magnificent Seven, none of the farmers, heroes, or villains here are people.

They’re ants.

The ants of the genus Sericomyrmex are peaceful farmers. They forage bits of vegetation, bring them back to their nests and grow fungus on them for food. Their lives aren’t all bucolic farmyard scenes in miniature, though. While many ants protect their colonies with specialized soldiers who can deliver powerful stings and bites, these six-legged agriculturalists are poorly armed, and can fight back only with their jaws. Unable to mount much of a defense against stinging foes, they’re regularly besieged by another ant species, Megalomyrmex symmetochus. Queens from this parasite species sneak into Sericomyrmex nests and form their own colonies within them, feeding on their hosts’ fungal crops, and sometimes their larva. They’ll also clip the wings of the virgin farmer queens, preventing them from forming new colonies and turning them into laborers. Instead of trying to fight the parasites and risk death, the farmers put up with them and supply them with room and board.

Biologists have found that the two groups are incredibly common with one another, and in some surveys, almost three quarters of Sericomyrmex nests are infested with Megalomyrmex. Even if they can’t fight back, why haven’t these farmers found some other way to rid themselves of their parasites?

One reason seems to be that the parasite is the lesser of two evils, and a good defense against an even bigger threat.

A third ant, Gnamptogenys hartmani, also raids the farmers’ colonies, taking over their gardens and nests and wiping out the inhabitants. The farmers are as defenseless against these pirates as they are against M. Symmetochus. G. hartmani has mastered a colony-conquering “agro-predator” lifestyle. Just two raiders can obliterate 70 percent of a Sericomyrmex colony, and the farmers that don’t perish usually flee and cede their home to the intruders.

When Gnamptogenys shows up at a Megalomyrmex-infested nest, though, the once unwelcome guest proves to be more of a help than a hindrance. The farmers will hide, while the more aggressive parasite soldiers confront and kill the invaders with their strong jaws and a little bit of chemical warfare. The Megalomyrmex ants possess a potent venom that they dole out through stings and by spraying into the air. It kills some of the raiders, and confuses others. The venom’s toxins appear to disrupt Gnamptogenys soldiers’ ability to recognize their nestmates, causing them to turn on each other and kill their own kind.

The arrangement hinges on a quirk of Megalomyrmex’s lifestyle. They don’t infest, eat, and move on like other parasites, but commit to a single host colony for life. Their success and survival depends on the farmers’ well-being.

To Rachelle Adams, an entomologist at the Smithsonian Institution whose research describes Megalomyrmex’s protective functions, the ants are more like mercenaries than pure parasites. They exploit their hosts, but that cost is compensated for by the defense they provide, and acting as soldiers for the farmers also protects their own interests. When trouble comes knocking, a parasitic win-lose relationship becomes a win-win.

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These Deep-Sea Worms Could Live More Than a Thousand Years

Plunge below the sparkling surface of the Gulf of Mexico, head down into the depths, and there you'll find the ancient ones, growing in clusters of drab tubes like piles of construction equipment. Scientists writing in the journal The Science of Nature report that some of these worms could be more than 1000 years old.

When it comes to marine organisms, the deeper you go, the slower and older life gets. Biologists have found an octopus that guarded her eggs for four and a half years. They've seen clams born during the Ming dynasty and sharks older than the United States. They've seen communities of coral that have been around for millennia.

Previous studies have shown that some species of tube worm can live to be 250 years old. To find out if the same was true for other species—in this case, the Gulf of Mexico's Escarpia laminata—researchers spent years watching them grow. They used a long-lasting dye called Acid Blue to mark six clusters of worms, then let them to go about their wormy business. A year later, they collected all 356 blue-stained tubes and brought them back to the lab to measure their growth.

By calculating the speed of the worms' growth and comparing it to the size of the largest individuals, the scientists could devise a pretty good estimate of the oldest worms' age.

And boy, are they old. The researchers' worm-growth simulation suggested that the most ancient individuals could be more than 9000 years old. This seems incredible, even for tough old tube worms, so the scientists calculated a more conservative maximum age: a mere 1000 years.

A millennium-long lifespan is an extreme and not the average, the paper authors note. "There may indeed be large E. laminata over 1000 years old in nature, but given our research, we are more confident reporting a life span of at least 250 to 300 years," lead author Alanna Durkin of Temple University told New Scientist.

Still, Durkin says, "E. laminata is pushing the bounds of what we thought was possible for longevity."

She's excited by the prospect of finding older creatures yet.

"It's possible that new record-breaking life spans will be discovered in the deep sea,” she says, “since we are finding new species and new habitats almost every time we send down a submersible.”

 

[h/t New Scientist]

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Animals
Watch as Hummingbirds Fly, Drink, and Flap Their Tiny Wings in Slow Motion
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Hummingbirds have more feathers per inch than nearly any other bird, but it’s hard to fully appreciate their luminescent colors when they beat their wings between 70 to 200 times per second.

For the enjoyment of birders everywhere, National Geographic photographer Anand Varma teamed up with bird biologists and used a high-speed, high-resolution camera to capture the tiny creatures in slow motion as they flew through wind tunnels, drank artificial nectar from a glass vessel, and shook water from their magnificent plumage.

[h/t The Kid Should See This]

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