Surface ciliation of anuran amphibian larvae: persistence to late stages in some species but not others.

Scanning electron microscopy was used to examine the surfaces of 21 species of tadpoles from six families, from Gosner Stage 25/26 until close to metamorphosis. Contrary to most previous reports, ciliated epidermal cells persisted until late stages in many but not all species and not at all locations examined. The commonest location for ciliated cells was around the nostrils, suggesting a role in chemosensation. Ciliated cells also occurred around the circumference of the eye, suggesting a cleaning role. Several species had ciliated cells on the tail. The densest, most regular arrays of ciliated cells occurred in species that tend to hang motionless in still-water pools, suggesting a respiratory function for these cells.