A chemical sensing mechanism that allows mud crabs to evade blue crabs calls for technological innovation in the field of sensing in a dark environment
Source: Or Amr
In the estuaries off the coast of Georgia, the water is so murky that if you dive there, you won't even see your hand. Under the cover of darkness, blue crabs feed on mud crabs, oysters, fish and more. In this dark environment, where crab eats crab, mud crabs, no larger than the tip of a thumb, try to stay away from the blue crabs like fire, and when you can't see anything, the only way to survive is to smell. Chemicals in blue crab urine portend a death sentence for mud crabs. The message is clear - hide or you will be eaten.
"Apparently, blue crabs don't want to send that message, but they can't help it. We all need to evacuate," says Dr. Julia Kubanek, a marine chemical ecologist at the Georgia Institute of Technology. Institute of Technology).
Of the six hundred chemicals that are secreted in the blue crab urine, only two signal a danger to the mud crabs. These chemicals are created when the blue crabs break down their meal, and are especially potent when their last meal is a mud crab. This invisible underwater messaging system has far-reaching effects. The urine of one blue crab that ate one mud crab in a certain estuary is enough to change the interactions in the food chain in the underwater ecosystem.
Dr. Kubanek and her colleagues investigated the sensing mechanism using a new technique called metabolomics - a comparison of chemical profiles. The researchers fed blue crabs different dietary foods that were broken down into urine samples. They extracted from each of the samples a threat level and a unique chemical profile. To get an estimate of the threat level, the researchers put shrimp into a tank of mud crabs. They then tested which urine sample caused cancer The mud eats less shrimp and hides more.This is how the researchers identified different chemical characteristics present in the samples that produced the highest level of threat.
Understanding that the interactions between predators and their victims in different marine ecosystems is significantly influenced by chemical cues may help conservation researchers to treat marine environments that contain fish and shellfish. In a biomimetic context, the study of the mud crabs' sensing mechanism, which allows them to detect certain chemicals dissolved in the marine environment, can form the basis for the development of sensors for various marine uses, for example, for early warning of chemical leaks.
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