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Mimicking caterpillar helps newborn bird avoid detection; sensor replicates organ found in spiders’ legs

Mimicking caterpillar helps newborn bird avoid detection

A baby bird in the Amazon rain forest has downy feathers with long, orange barbs and white tips that make it look like a poisonous, hairy caterpillar, researchers report. The disguise helps the cinereous mourner avoid the clutches of hungry snakes and monkeys, said Gustavo Londoño, an ecologist at Icesi University in Cali, Colombia, and an author of a new paper about them in the American Naturalist. The birds are rarely seen by humans and, as a result, hard to study.

“They are very shy and quiet, and their vocalization is a very low whistle,” Londoño said. “They stay in heavily forested areas in the Amazonian.”

So when the researchers happened upon a nest with two eggs in Peru, they set up a camera to monitor them. Only one egg hatched, and when the researchers took measurements of the baby, it started moving its head very slowly from side to side, much like the hairy caterpillar it resembles. The nestling made the same cautionary movement when its parents arrived with food. “It was only when the parents started making a particular vocalization that the bird opened its mouth and asked for food,” Londoño said.

After about 14 days, the bird no longer looked so much like caterpillar, but by then it had the strength to jump out of the nest if a predator arrived.

Vibration sensor replicates organ found in spiders’ legs

One of the most sensitive vibration sensors in the natural world is the lyriform organ, located in the legs of many spiders. The organ has a series of parallel slits of different lengths, much like the strings on the harplike instrument called the lyre, and helps spiders detect prey.

Now, researchers from South Korea have developed a highly acute sensor, made of a thin platinum-coated polymer, that was inspired by the organ.

“The polymer is very flexible, so we can bend it,” said Mansoo Choi, a mechanical engineer at Seoul National University and an author of the research, which appears in Nature. “And depending how much you bend it, you can generate controlled cracks.”

The sensor, just two-tenths of an inch by four-tenths of an inch, could be worn on the wrist to monitor and gather health information, Choi said.

– New York Times