The quantitative abilities of lizards may have their limits.
From horses to salamanders, lots of different species display some form of number sense, but the phenomenon hasn’t been investigated in reptiles. So a team of researchers in Italy set up two experiments for 27 ruin lizards (Podarcis sicula) collected from walls on the University of Ferrara’s campus. In the first test, the team served up two house fly larvae of varying sizes. Lizards consistently chose to scarf down bigger maggots.
Then in the second experiment, the researchers gave lizards a choice between different numbers of larvae that were all the same size. The lizards didn’t show a preference. While the data suggest that the reptiles do discriminate between larger and smaller prey, they don’t distinguish between higher and lower numbers of maggots in a meal, the scientists report April 12 in Biology Letters.
The researchers cite two potential explanations for the discrepancy. Selecting larger prey rather than more prey might sometimes be advantageous for a predator. Or reptiles simply lack the numerical know-how seen in vertebrate relatives, such as fish.