Selection for efficiency in food capture may be a dominant influence in the evolutionary biology of predaceous cave animals. A sample of 8 Haideotriton wallacei from a natural population contained 21 feeding boluses in their digestive tracts. Fourteen of these boluses contained food, demonstrating success in at least 67% of the feeding attempts.
Peck, Stewart B..
Feeding efficiency in the cave salamander Haideotriton wallacei.
International Journal of Speleology,
Available at: http://scholarcommons.usf.edu/ijs/vol5/iss1/1