This paper describes the dentition and diet of a population of Smooth newt larvae. The development of the teeth and their increase in number with age are discussed. The number of teeth on all five tooth-bearing bones appear to be controlled by a single developmental system. Young larvae eat chydorids, daphniids and cyclopoid copepods; after they reach a total length of about 15 mm, chironomid larvae comprise the greater part of the diet. In the study population, ostracods were not eaten, and cannibalism was not observed. There was no tendency for larger larvae to select larger individuals of a given species of prey.
It is suggested that the exponential rate of growth in weight forces larvae of more than about 15 mm total length to switch from passive to active hunting. This enables them to catch larger prey, at the expense of incurring a higher rate of mortality. This increase in mortality is associated with a reduction in the variation of morphological characters, including dentition, which is thought to be caused by natural selection. The function of different components of the dentition are discussed. It was found that larvae of a given age which have more teeth than average have in their guts fewer prey than average, and an explanation is suggested.