Parasites make cannibal shrimp hungry

Forget fava beans and a nice Chianti. Parasites stoke hunger for living flesh among cannibals — at least in river shrimp. Being infected with a microscopic parasite (Pleistophora mulleri) seems to give freshwater shrimp (Gammarus duebeni celticus) in Northern Ireland a stronger appetite for their fellow crustaceans, researchers report 18 March in Royal Society Open Science.

Cannibalism is commonplace in nature, and adult river shrimp regularly eat younger shrimp alive. In lab experiments, infected cannibals ate twice as much shrimp as uninfected cannibals and were more likely to eat healthy shrimp rather than infected ones. Hosting a parasite may require the sick shrimp to gorge to survive, the researchers conclude.