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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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Animals
Scientists Discover 'Octlantis,' a Bustling Octopus City
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Sylke Rohrlach, Wikimedia Commons // CC BY-SA 4.0

Octopuses are insanely talented: They’ve been observed building forts, playing games, and even walking on dry land. But one area where the cephalopods come up short is in the social department. At least that’s what marine biologists used to believe. Now a newly discovered underwater community, dubbed Octlantis, is prompting scientists to call their characterization of octopuses as loners into question.

As Quartz reports, the so-called octopus city is located in Jervis Bay off Australia’s east coast. The patch of seafloor is populated by as many as 15 gloomy octopuses, a.k.a. common Sydney octopuses (octopus tetricus). Previous observations of the creatures led scientists to think they were strictly solitary, not counting their yearly mating rituals. But in Octlantis, octopuses communicate by changing colors, evict each other from dens, and live side by side. In addition to interacting with their neighbors, the gloomy octopuses have helped build the infrastructure of the city itself. On top of the rock formation they call home, they’ve stored mounds of clam and scallop shells and shaped them into shelters.

There is one other known gloomy octopus community similar to this one, and it may help scientists understand how and why they form. The original site, called Octopolis, was discovered in the same bay in 2009. Unlike Octlantis, Octopolis was centered around a manmade object that had sunk to the seabed and provided dens for up to 16 octopuses at a time. The researchers studying it had assumed it was a freak occurrence. But this new city, built around a natural habitat, shows that gloomy octopuses in the area may be evolving to be more social.

If that's the case, it's unclear why such octo-cities are so uncommon. "Relative to the more typical solitary life, the costs and benefits of living in aggregations and investing in interactions remain to be documented," the researchers who discovered the group wrote in a paper published in Marine and Freshwater Behavior and Physiology [PDF].

It’s also possible that for the first time in history humans have the resources to see octopus villages that perhaps have always been bustling beneath the sea surface.

[h/t Quartz]

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Criminal Gangs Are Smuggling Illegal Rhino Horns as Jewelry
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Valuable jewelry isn't always made from precious metals or gems. Wildlife smugglers in Africa are increasingly evading the law by disguising illegally harvested rhinoceros horns as wearable baubles and trinkets, according to a new study conducted by wildlife trade monitoring network TRAFFIC.

As BBC News reports, TRAFFIC analyzed 456 wildlife seizure records—recorded between 2010 and June 2017—to trace illegal rhino horn trade routes and identify smuggling methods. In a report, the organization noted that criminals have disguised rhino horns in the past using all kinds of creative methods, including covering the parts with aluminum foil, coating them in wax, or smearing them with toothpaste or shampoo to mask the scent of decay. But as recent seizures in South Africa suggest, Chinese trafficking networks within the nation are now concealing the coveted product by shaping horns into beads, disks, bangles, necklaces, and other objects, like bowls and cups. The protrusions are also ground into powder and stored in bags along with horn bits and shavings.

"It's very worrying," Julian Rademeyer, a project leader with TRAFFIC, told BBC News. "Because if someone's walking through the airport wearing a necklace made of rhino horn, who is going to stop them? Police are looking for a piece of horn and whole horns."

Rhino horn is a hot commodity in Asia. The keratin parts have traditionally been ground up and used to make medicines for illnesses like rheumatism or cancer, although there's no scientific evidence that these treatments work. And in recent years, horn objects have become status symbols among wealthy men in countries like Vietnam.

"A large number of people prefer the powder, but there are those who use it for lucky charms,” Melville Saayman, a professor at South Africa's North-West University who studies the rhino horn trade, told ABC News. “So they would like a piece of the horn."

According to TRAFFIC, at least 1249 rhino horns—together weighing more than five tons—were seized globally between 2010 and June 2017. The majority of these rhino horn shipments originated in southern Africa, with the greatest demand coming from Vietnam and China. The product is mostly smuggled by air, but routes change and shift depending on border controls and law enforcement resources.

Conservationists warn that this booming illegal trade has led to a precipitous decline in Africa's rhinoceros population: At least 7100 of the nation's rhinos have been killed over the past decade, according to one estimate, and only around 25,000 remain today. Meanwhile, Save the Rhino International, a UK-based conservation charity, told BBC News that if current poaching trends continue, rhinos could go extinct in the wild within the next 10 years.

[h/t BBC News]

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