A critical review of freshwater crayfish as amphibian predators: Capable consumers of toxic prey?

Consumption of amphibian eggs and larvae by crayfish has been widely reported despite many amphibians being unpalatable and/or toxic to other predators. The aim of this review was to gather information regarding the consumption and/or avoidance of toxic amphibians by these omnivores. We then appraised the extent of toxin consumptive ability in terms of crayfish phylogenetic history so as to speculate as to the evolutionary history of this trait. Reports indicating an ability to tolerate amphibian toxins were collected and reviewed for 12 freshwater crayfish species. In reviewing these, we have established that freshwater crayfish appear to be tolerant of a range of toxic amphibians, often consuming large numbers of eggs and larvae without lethal or apparent sublethal effects. Toxin tolerance was evident within both superfamilies (Astacoidea and Parastacoidea) suggesting that tolerance may be a primitive trait in freshwater crayfish.