SKULL GROWTH IN CANNIBALISTIC TIGER SALAMANDERS, AMBYSTOMA-TIGRINUM

This study compared skull growth in cannibal and non-cannibal tiger salamanders, Ambystoma tigrinum. Skull measurements from cleared and stained larvae suggested that the development of small cannibals less than 70 mm SVL was characterized by the differential, accelerated growth of the skull. Though the skulls of cannibals remained larger than those of non-cannibals, the trophic apparatus of non-cannibals exhibited accelerated growth so that it was difficult to accurately identify cannibals or non-cannibals on the basis of skull size at snout-vent lengths greater than 70 mm. This study suggests that the soft-tissue, functional matrix of the head dictates head size, and that the increased head size in cannibals is compensatory growth responsive to the increased functional demands of macrophagy.