Peppered moth caterpillars (桦尺蠖毛虫)live north of the equator. But if you’ve never seen one, don’t feel bad: They’re experts at blending in (融为一体). Each caterpillar looks like the branch it stays on, straightening its body into a stick-like shape. It also changes its color to match the branch’s color, whether white, green or brown.
According to a paper published in Communications Biology, the caterpillars sense the color of their surroundings not only with their eyes but also with their skin.
Ilik Saccheri, an author of the paper, normally studies the adult moth. This requires keeping a lot of caterpillars around. Years of observation awakened his curiosity about their color-changing abilities. Each caterpillar hatches tiny and black, and in its early days is blown around by the wind. Once it falls on a plant, it must disguise itself to avoid being spotted by birds.
“I was a bit disbelieving that they could change that only using their eyes,” Dr. Saccheri said.
Amy Eacock, a graduate student in Dr. Saccheri’s lab decided to investigate. First, she tested the caterpillars’ eyes for light-sensitive proteins called opsins (视蛋白). “We did the skin as kind of a negative control,” said Dr. Eacock. “But then we found they were expressed in the skin as highly as they were in the head.”
That’s when she suggested blindfolding the caterpillars. The researchers could cover their eyes, place them on different-colored dowels (木钉) , and see if they still changed to match.
“I thought it was kind of a crazy idea,” Dr. Saccheri said. The blindfolding itself was a difficult task, involving black paint, a tiny paintbrush, a microscope and lots of patience, Dr. Eacock said. Caterpillars molt (蜕皮) several times over their lives, which required that they be blindfolded again frequently.
But Dr. Eacock persisted, eventually testing more than 300 caterpillars. Over and over again, the blindfolded caterpillars successfully changed color to blend in.
Many questions remain, but the behavior alone impressed the researchers. Dr. Eacock said, “I remember turning to Ilik one day and saying, ‘You know what? The caterpillars are cooler than the moths.’” “Yes. They’re pretty amazing,” Dr. Saccheri agreed.
【小题1】What can we learn about peppered moth caterpillars?| A．They feed on fresh tree branches. |
| B．They can be found easily across the world. |
| C．They can adapt to different environments. |
| D．They change their body color to match living conditions. |
| A．Caterpillars have a fear of height. |
| B．There are opsins in caterpillars’ skin. |
| C．Caterpillars molt several times in their life. |
| D．There is something strange in caterpillars’ eyes. |
| A．It was hard to operate. |
| B．It was well designed. |
| C．It was inspiring but the evidence was unreliable. |
| D．It was a failure but the methods deserved praise. |
| A．To solve a mystery. | B．To introduce a new species. |
| C．To present a scientific study. | D．To awaken readers’ curiosity. |
