Oysters on drugs

When I used to teach invertebrate zoology, I found a surprising number of studies where they exposed different invertebrates to different drugs. My favourite was the spiders on drugs. You can search it and find images of the webs they built after exposure to different drugs. Today, an article popped up about oyster larvae and drugs, so, of course, I read it.

The interesting thing was why they were testing this. Due to human drug use, drugs like fentanyl, ketamine, and a byproduct of cocaine end up contaminating natural water bodies. This then exposes animals living in that water to these drugs. Salcedo and colleagues (2025) looked at the impacts of these drugs on oyster larvae.

At the concentrations present in the environment, the oyster larvae showed different swimming patterns, reduced survival, and changes in their gene expression. Different drugs had different impacts. Ketamine exposure made the larvae motionless, while the cocaine byproduct changed the gene expression. Fentanyl caused them to swim in circular patterns.

Clearly, the extent of illicit (and legal) drug use among humans is a systemic problem that needs to be addressed for human health. But research like this highlights that it isn’t just humans who are at risk. And to be clear, I do not agree with the current measures being taken by multiple governments to criminalize drug users. We need to ask instead what is making this the only option they see and address the systemic barriers to healthy living.