Researchers at the University of Leeds, Queen's University Belfast and Stellenbosch University in South Africa looked at cannibalism among freshwater shrimp in Northern Ireland.
They found a tiny parasite, Pleistophora mulleri, not only significantly increased cannibalism among the indigenous shrimp Gammarus duebeni celticus but made infected shrimp more voracious, taking much less time to consume their victims.
Dr Alison Dunn, Reader in Evolutionary Biology in the University of Leeds' Faculty of Biological Sciences, who led the study, said: "Cannibalism is actually fairly common in nature. Our work is the first study to ask if cannibalism is affected by being parasitised."