Did you know that crabs find their food using their sense of smell, not their eyes? 

Carbon dioxide released into the atmosphere from pollution is absorbed by our oceans, making them more acidic and putting our coastal and marine ecosystems under tremendous stress.  

One of the creatures that this is affecting are crabs, and research released this week shows that one of their most important senses are degrading. 

Published in the journal Global Change Biology, the study looked at the Dungeness Crab, which is a very popular crab for humans to eat. Their populations have been declining over recent years, which is having an effect on the local fishing industry. 

The Dungeness crab has poor eyesight, so they rely on their sense of smell to detect their food and to sense predators in the water. They sniff using a small, waving antennae which help them to smell chemical signals in the water. Once they detect an important scent, they flick this antennae faster to help process the signal. 

When the researchers placed the crabs in slightly acidic water, the found that the nerve response that prompts faster flicking was affected and the crab couldn’t detect a smell that had been added to the water. The scientists had to add ten times more scent into the acidified water for the crabs to be able to detect it. 

Losing their sense of smell due to the change in ocean acidity means the crabs will be struggling to sniff out their food in the wild, which leads to the females having less energy to produce eggs, explaining the rapid decline in their population. 

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