Oysters are critical members of our coast, but today they live in more acidic environs thanks to increasing ocean carbon dioxide (CO2). Some marine microbes can combat acidity, and those microbes may be oysters' "secret weapons" in combatting the challenges of acidity. We will build a new sensor/sampler to gently "sip" water from inside oysters to measure microbial composition, chemistry, and acidity inside the oyster, and to see if/how the internal microbiome helps manage acidity.