Drunken copepods

Tiny plankton that slurp up copious amounts of a toxic substance end up behaving oddly and indulging in risky behaviour. Sound familiar? Just like people having a few too many drinks at a house-party, copepods of the Atlantic Ocean can show effects of intoxication. Their poison of choice obviously isn’t alcohol, though, it is a form of rare algae.

Copepods are tiny, shrimp-like invertebrates. They feed on a range of things, but have a particular appetite for the rare algae Alexandrium fundyense, otherwise known as ‘red tide’. When it blooms, the copepods tuck in, and that’s where their problems start. For the algae is toxic, and when ‘drunk’ on it, the copepods’ behaviour changes.

Normally, a copepod swims slowly, but in a looping, erratic fashion. This makes it harder to detect, and if spotted, the lack of straight-line swimming makes it difficult to target. In contrast to our own bumbling intoxicated wobbles, copepods actually get 25% faster and swim in straight lines when ‘drunk’. But this reckless speed and straightforward swimming actually makes them more vulnerable – it attracts too much attention as they travel further, and zoom carelessly within range of far more predators. They become up to 50% more likely to be predated, suggests a study by University of Maine scientists.

Does the intoxicating algae have any other effects, not just a potential hangover for surviving copepods, but far-reaching impacts of the toxic algae further up the food chain? As further studies examine copepods, red tide, and the higher echelons of the food chain, time will tell.

 

Originally published in Biosphere Magazine Issue 17.

Rachel S. Lasley-Rasher et al (2016) Intoxicated copepods: ingesting toxic phytoplankton leads to risky behaviour, Proceedings of the Royal Society B: Biological Sciences DOI: 10.1098/rspb.2016.0176

Image credit: Uwe Kils / Wikipedia

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