The diversity of sticky frog tongues

Aims Frogs are well known for their use of sticky tongues to capture elusive prey items. The movements of the tongues are extremely fast and single feeding events usually happen within tenths of a second 1-3 . The forces acting on the tongues during feeding can be multiple times the body weight of the animals 4 . Tongue feeding in frogs is diverse, comprising species that only slightly protrude the tongue out of the mouth (i.e. tongue pulling) and species that fire ballistic tongues towards distant targets 5 (Fig. 1). While the kinematics of tongue movements in different species of frogs have received some attention in the past 5 , little is known on how the different tongue feeding modes relate to anatomical differences. Further, although previous studies mentioned an unusual interdigitation of muscle fibers from different tongue muscles in frogs 6 , the three-dimensionality of this muscle fiber arrangement could not be resolved due to limitations in the methods used (manual dissection and histology). Here we used micro-CT imaging to explore the three-dimensional organization of frog tongues. The aim of this study is to provide detailed descriptions of frog tongue anatomy in relation to differences in the feeding modes of frogs.