The city of Warsaw, Poland, uses eight mussels with sensors hot-glued to their shells to monitor and automatically shut off the city water supply if the shellfish so chooses.
When water quality drops, mussels close their shells, tripping the sensor and alerting control computers. When four of the eight mussels close their shells, the control system automatically shuts off the water supply. Mussels are employed for 3 months before being put back into the wild, and more than 50 water plants around Poland employ this same technique.
Adult clams and oysters can filter up to 50 gallons of water per day, but if the water becomes too toxic, they’ll close their shells up and ride it out.
More at: Atlas Obscura
Except where otherwise noted, content on this site is licensed under a Creative Commons Attribution 4.0 International license.