Friday, June 30, 2006

Torturing Ants in the Name of Science

Via 3QuarksDaily, the National Geographic reports:
Hunting for food, ants roam haphazardly. But when they find it, they use celestial cues, perhaps from the sun, to head back to their nests more or less in a straight line—rather than retracing the tortuous journeys they'd made on their outbound searches. Instead, a new study suggests that ants have internal "pedometers," or step counters, that help them gauge how far they have traveled. Food was placed about 33 feet (10 meters) from an ant nest. When ants found the food the researchers collected the insects before they had time to carry it back to the nest.

Twenty-five of the ants were then put gently on their backs. Scientists glued stilts made of pig bristles to the insects' legs—a delicate procedure that had to be done quickly so the ants wouldn't forget what they were doing and fail to return home. Another 25 ants had their legs surgically shortened by chopping off part of the bottom segment. For the ants on stilts, each step now covered more distance than they were used to. They overshot the nest, running an average of more than 50 percent farther than they should have. Those with shortened legs undershot by nearly as much.
First comment: This result is consistent with other research suggesting that ants figure out their location relative to their nest using "dead-reckoning". This technique, which seems incredible without a computer, works this way: the ant keeps track of how many paces it has walked and how many times it has turned, and what angles it has turned through, and numerically integrates to figure out its current position.

Second comment: They chopped off a poor bug's legs? They glued hog bristles to another bug's legs? Ew!!! Sounds like evil scientists from a bad science fiction movie experimenting with brain transplants.

This reminds me of what an old friend, Mark Muldoon, once said about people who grow bonsai trees: "What if somebody cut your arms and legs off to try to get you to grow into an interesting shape?"


Blogger Kyle McCullough said...

I'm impressed that the ants could walk on stilts. I never could get the hang of that. I'm also rather amazed that the ants simply walked home on the stilts, rather than chewing them off their feet.

As for the torture aspect, that's nothing compared to what they do to ants at Guantanamo Bay.

10:24 PM  
Blogger Daryl McCullough said...

Kyle, I have the impression (which may be wrong) that insects' limbs are like human hairs or fingernails: they don't have any nerves or blood vessels in them, so snipping them or adding to them isn't that uncomfortable.

5:59 PM  
Blogger RichM said...

I thought that houseflies have their chemoreceptors on the bottoms of their feet, so when they land on your plate they have a taste of what you're having. Don't know about ants, though.

9:30 AM  

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