Trap-Jaw Ants Jump with Their Legs, Too
Known for using their powerful jaws to launch themselves into the air, the insects have another trick in their escape arsenal.
Trap-jaw ants are known for using their powerful jaws to launch themselves into the air, somersaulting several times their own body length to evade predators. But some of these ants have another trick in their escape arsenal. Scientists recently discovered a trap-jaw species that leaps with its legs, a behavior that is extremely rare in ants and previously unknown in the trap-jaw family. Talk about getting a jump on the competition.
Magdalena Sorger of North Carolina State University and author of the study describing this unusual behavior, was collecting trap-jaw ants in Borneo with a field assistant in 2012, when they noticed something "extremely strange," she told Live Science. [Watch Trap-Jaw Ants Show Rare Jumping Ability]
Sorger was used to seeing Odontomachus rixosus, a species of trap-jaw ant, perform jaw jumps, which typically propelled the ants backward (sometimes onto a scrutinizing scientist's face). But the ants were doing something quite different.
"They were jumping forward," said Sorger, who is an evolutionary ecologist. "I'd never seen them do that before."
To "jump" with their jaws, trap-jaw ants stretch their massive mandibles wide and then snap them shut. Acting like a spring-loaded catapult, the closing snap shoots the ant out of harm's way. [Watch Ants Use 'Spring-Loaded' Mandibles To Escape From Predators]
Other ant species employ equally novel solutions for getting around. Wingless tropical ants drop from their tree habitats when threatened, using their hind legs as rudders to help them glide to safety. Some ant species are swimmers, while some ford watery obstacles by linking their legs to form living rafts and bridges. Still others can "limbo," navigating under low-hanging barriers without losing speed.
But leg jumping in ants is exceptionally rare - of 326 ant genera, only three are known to jump with their legs. Once Sorger noticed this forward jumping in the Borneo trap-jaws, she started looking more closely at how they behaved when she collected them.
"I saw them jumping almost every time," she recalled.
Initially, Sorger suspected the ants might be jumping because that was an easier way to navigate their leafy habitat. She returned to Borneo in 2013 specifically to document and analyze leg-jumping, and soon realized that the ants jumped in response to disturbances.
"They would try to escape from you by hopping forward," Sorger told Live Science.
Sorger found that touching the ants' legs induced jumping. Some of those were jaw jumps, but most of the time they were jumping with their legs. And Sorger observed that leg-jumping had clear advantages. The jaw jumps, while swift and powerful, were difficult for the ants to control. The motion typically propels the ants backward, flipping them upside-down and requiring a moment of recovery time, which could be critical in escaping a hungry predator, she said.
Even among the other groups of ants that jump with their legs, the trap-jaw jumpers stand out. While all the leg-jumpers - including the trap-jaws - are solitary hunters, the three previously known groups share one feature that trap-jaws lack: large eyes. Sorger pointed out to Live Science that the other ant groups use their jumps to capture prey, which would require superior vision, but she did not observe the trap-jaw species jumping forward to hunt. "They go under the leaves, and you can hear them catch prey - it's a little snap - but you can't see them," Sorger explained. She suggested that perhaps the trap-jaws' mandibles were enough of a hunting advantage, so it didn't require the visual capabilities of its smaller-jawed cousins.
Sorger anticipates that further study will confirm if trap-jaws' forward jumps are used solely for escaping from danger, or for ambushing prey, as well. Closer examination of the biomechanics of trap-jaws and other jumping ants may also help explain why this handful of exceptions among the ant family is able to spring ahead.
The findings were published online today (Dec. 1) in the journal Frontiers in Ecology and the Environment.
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A species of trap-jaw ant,
Insects and other creepy crawlies may be tiny, but their lineages are mighty, finds a new study that determined the common ancestor of mites and insects existed about 570 million years ago. The study, published in the latest issue of the journal Science, presents an evolutionary timeline that settles many longstanding uncertainties about insects and related species. It found that true insects first emerged about 479 million years ago, long before dinosaurs first walked the Earth. Co-author Karl Kjer, a Rutgers entomologist, explained that mites are arthropods, a group that's distantly related to insects. Spiders and crustaceans are also arthropods.
Spiders such as the huntsman spider can, like mites, trace their lineages back to about 570 million years ago, according to the new study. The researchers believe that the common ancestor of mites, spiders and insects was a water-dweller.
Millipedes, such as the one shown here, as well as centipedes are known as myriapods. The most recent common ancestor of myriapods and crustaceans lived about 550 million years ago. Again, this "mother of many bugs" would have been a marine dweller. Kjer explained, "You can't really expect anything to live on land without plants, and plants and insects colonized land at about the same time, around 480 million years ago. So any date before that is a sea creature." Moving forward in time, the most common ancestor of millipedes and centipedes existed a little over 400 million years ago. The leggy body plan has proven to be extremely successful.
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Dragonflies and damselflies have family histories that go back about 406 million years. Kjer said that such insects looked differently then, however. "For example," he said, "they had visible antennae." Their distant ancestors were among the first animals on earth to fly.
"Parasitic lice are interesting, because they probably needed either feathers or fur," Kjer said. As a result, they are the relative newbies to this list. Nonetheless, the researchers believe it is possible that ancestors of today's lice were around 120 million years ago, possibly living off of dinosaurs and other creatures then.
Crickets, katydids and grasshoppers had a common ancestor that lived just over 200 million years ago, and a stem lineage that goes back even further to 248 million years ago. A trivia question might be: Which came first, these insects or grass? The insects predate the grass that they now often thrive in.
Dinosaur Era fossils sometimes include what researchers call "roachoids," or wing impressions that were made by ancestors to today's roaches, mantids (like the praying mantis) and termites. "Some cockroaches are actually more closely related to termites than they are to other cockroaches," Kjer said, explaining that this makes tracing back their lineages somewhat confusing. He and his colleagues determined that the stem lineage goes back about 230 million years, while the earliest actual cockroach first emerged around 170 million years ago.
Termites and cockroaches have a tightly interwoven family history. Termites similar to the ones we know today were around 138 million years ago. Now we often think of termites as pests, but they are good eats for many different animals, which back in the day would have included our primate ancestors.
Flies like houseflies that often buzz around homes belong to the order Diptera, which has a family tree that goes back 243 million years ago. The most recent common ancestor for modern flies lived about 158 million years ago, according to the study. There is little doubt that the earliest humans, and their primate predecessors, had to contend with pesky flies and all of the other insects mentioned on this list. All of these organisms are extremely hardy. The researchers determined that, in the history of our planet, there has only been one mass extinction event that had much impact on insects. It occurred 252 million years ago (the Permian mass extinction), and even it set the stage for the emergence of flies, cockroaches, termites and numerous other creepy crawlies.