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Sheila Patek: The breakneck world of ants that bite fast and jump high
Andy Suarez and Brian Fisher (California Academy of Sciences ant expert and source of the original FedEx) had both experienced O. bauri's jumps up close and way too personal. When a large intruder (like a field biologist) stumbles onto the ants' nest, it triggers a "popcorn" effect: multiple ants fling themselves into the air. Perhaps accidentally, some of them land on the intruder and proceed to inflict painful stings. These jumps directly into the air are called "escape jumps," but the ants also deploy another tactic, called the "bouncer defense," in which they attack an invader with a strike, while simultaneously flinging themselves away.
Though Sheila, Joe, Andy, and Brian had begun with a simple question (How fast are they moving?), now they had a specific hypothesis. They suspected that the ants were using their jaws to jump and that they were intentionally doing so not just misfiring as had been debated in the literature. So the team set up cameras to capture exactly what happened during an ant's jump.
"When we first got the videos, Brian who has discovered hundreds of species of ants and knows everything there is to know about ants was jumping up and down because it was so surprising and exciting to see what they were doing. We all were so excited! We were grabbing people from the hall to come see these videos," raves Sheila. They were watching something that no one had ever been able to see before and it was quite clear from the film: "For the escape jump, it's definitely intentional. The ants are setting up a jump with their jaws definitely not an accident." The results of the investigation supported their hypothesis.
And now, there are more questions to answer. It's easy to assume that escape jumps and the bouncer defense are adaptations for nest defense and survival but according to Sheila, that's a big assumption that actually needs to be tested experimentally: "You can see some really high-performance, cool behavior and not actually be sure whether it's adaptive and whether it's on purpose. With the ants, the truth is that if you are generating that much force to squash things, one accidental consequence is that if you fire against something bigger than you are, you're going to go backwards whether you wanted to or not. We often assume that the 'designs' we see in nature must be perfect and they're not. Probably the ants are just messing up sometimes...It's really hard to show if a behavior is conveying a benefit of any kind." The next steps, which are already in the works, involve doing behavioral experiments to determine when the ants perform which jump and whether they gain any advantage (like protecting the colony better or escaping with their lives) by performing a jump. Ultimately, Sheila and her colleagues want to learn about the macroevolutionary patterns of the trap-jaw how and why the components of the trap-jaw were assembled over evolutionary time. But that is a long term project. Says Sheila, "This is the first paper we've ever written on the topic. There's years and years more work to do to understand the behavior." So stay tuned!
To learn more about Sheila's research on this topic, see these related resources:
Movie clips by Sheila Patek and her collaborators; Odontomachus bauri photo © Alex Wild.
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