Natures wonders: moths fake out bats (Introduction)

by David Turell , Sunday, May 26, 2024, 15:49 (113 days ago) @ David Turell

Mimic another form and live:

https://knowablemagazine.org/content/article/living-world/2021/prey-tell-how-moths-elud...

"The moths that bats chase, for their part, have evolved a broad array of biological tricks to avoid becoming treats for the bats.

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"From warning cries and jamming bat signals to creating false targets and sound-absorbing cloaking devices, here are some of the ways that moths have fought back through the 65-million-year arms race between them and their furry, flying predators.

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"At first, the function of moth clicks was unclear. Were they used to startle bats, to interfere with echolocation, or to warn about an unpleasant taste? Many of the clicking moths were tiger moths, a group including many that taste nasty to bats because their bodies are filled with noxious chemicals acquired from their food.

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"In a series of trials, Conner and then-graduate student Jesse Barber, now at Boise State University, found that bats quickly learned to associate moth-clicking with a bad taste, and thereafter avoid eating them.

"Not only that: Other, perfectly tasty moth species, the scientists found, had evolved to avoid bat predation by mimicking the bad-tasting tiger moth’s “don’t eat me” clicks. A devious disguise.

"Some species of tiger moths have different acoustic defenses. Physiological ecologist Aaron Corcoran, who did graduate studies with Conner and now runs a bat lab at the University of Colorado at Colorado Springs, discovered that certain tiger moths, upon hearing bat echolocation, could turn on a jamming signal. As the bat closes in, moths begin producing 4,500 clicks per second, throwing off bat ranging. With bats unable to discern target distance, moths could get away.

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"Using high-speed infrared videography to test how long-tailed luna moths (Actias luna) fared in a flight room with big brown bats (Eptesicus fuscus), Barber, Kawahara and others found a strong clue. In over half of the trials, the spinning hindwing tails of tethered luna moths lured echolocating bat attacks away from their vulnerable bodies, toward non-essential appendages. Moths with intact tails had a 47 percent survival advantage over those with tails removed. The tails are twisted, so when the moth flies, they flutter. Kawahara suggests that they act as a decoy, masquerading as a little moth: a false acoustic target.

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"Ever wondered why some moth bodies are so fuzzy? That’s a neat trick too. Analogous to visual camouflage, hairlike scales on a moth thorax are for stealth acoustic camouflage, like the fibrous sound absorbers found in homes, offices and concert halls.

"Ideally, as a moth, you’d need to have the equivalent acoustic protection on a wing as on your body, “but you can’t fly if you put 2 millimeters of fur on the upper end of your wing,” Holderied says. That creates a conundrum. So evolution has delivered moth wings layered all over with tiny, light, thin scales of different shapes and sizes. “It’s beautiful,” says Holderied. Tuned to absorbing a multitude of different frequencies, moth wings cloak the bounce-back of sound with what Holderied calls a “perfect carpet.'”

Comment: again, it raises the question of adaption by design or by incremental steps of natural evolution. The level of complexity in acoustic science is obvious to us, but at the moth level I think they had designer help.