Source: They failed to change color because the ship was too noisy - China Digital Science and Technology Museum
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When testing the harm of ocean noise to species, the researchers found that crabs exposed to the noise had a poorer ability to change color and camouflage, and were slower to flee in the face of simulated predators.
Large ocean-going vessels, such as oil tankers and cruise ships, produce a lot of noise when sailing, and their underwater travel distances are very long, which becomes noise pollution and interferes with the sound communication of marine mammals, fish and other animals.
"When the ship is too noisy, the sound of the animals communicating with each other is muffled. Emily Carter, a sensory ecologist at the University of Exeter, said. She wondered whether ship noise was just as harmful to animals that did not communicate soundly. For example, the juvenile Shore Crab, which uses camouflage colors to avoid predators. "They can blend in with their environment by changing their color, and it is basically difficult for predators to spot them. ”
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Carter suspected that the pressure caused by the noise of these boats would interfere with the process of discoloration. To confirm this, Carter and his colleagues captured some dark-shelled juvenile crabs and brought them back to the lab, where they were placed in a tank filled with white gravel and played softly with a natural background sound from underwater speakers throughout the day;
Carter said that some crab-feeding waterbirds can see ultraviolet light, so she uses UV photography to determine how well the crabs integrate into their new habitat over time. "Through the eyes of the waterfowl, that is, from the bird's point of view, are they camouflaged? Are they exposed? How conspicuous are they?"
After 8 weeks, the crabs that only heard natural background sounds became lighter in color and more successfully camouflaged. "But the color of the crabs that were exposed to the noise of the boats did not change much. When the experiment ended, they were unable to successfully disguise themselves. It is also easier to be spotted by natural predators. ”
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In addition, in another experiment, the crab listening to the noise of the ship failed to escape when simulating a predator attack. "They're either not reacting at all, or they're reacting at all, but they're reacting much more slowly. As a result, they are easier to catch in real-world situations. ”
Carter explained that the stress caused by boat noise can interfere with hormones in crabs that regulate discoloration, or weaken the energy needed to change color effectively. The study was published in the journal Current Biology. The study not only highlights the unintended consequences of noise pollution, but also points out that excessive stress is not only harmful to humans, but also fatal to animals that need peace and quiet.