Crayfish Prefer Exotic Meals

Conventional wisdom says that if you offer a crayfish a meal of native plants it eats everyday, and a meal of exotic plants it has never seen before, it will stick to what it knows best. But, in a recent study, scientists found that crayfish preferred the more exotic chow three to one.

This finding runs against Charles Darwin's enemy release hypothesis, proposed in 1859. This hypothesis states that exotic species become invasive because they are no longer at risk of being eaten by their natural enemies, allowing them to flourish and crowd out native species.

"What enemy release doesn't take into account is that while exotic plants may be free from their so-called natural enemies from their home range, they gain novel enemies in their new range," said John Parker, a graduate student at Georgia Tech. "Because they've never had to adapt to being eaten by these consumers, they may lack the appropriate defenses to ward them off, essentially going from the frying pan into the fire."

Parker and Mark Hay, a professor at Georgia Tech, paired 10 exotic plants with related native plants and offered them to two species of crayfish native to the southeastern United States. When given the choice, the crayfish preferred the exotic species three to one.

This finding may help point to better ways of controlling invasive species, which some estimate cause more than $137 billion in damage per year in the US. Currently the most common way of dealing with these pests are environmentally unfriendly herbicides.

This research is detailed in the Sept. issue of the journal Ecology Letters.