 Food is mostly selected by sight, even in conditions of dim light. Movement of the prey triggers a feeding response. Frogs have been caught on fish hooks baited with red flannel and green frogs (Rana clamitans) have been found with stomachs full of elm seeds that they had seen floating past. Toads, salamanders and caecilians also use smell to detect prey. This response is mostly secondary because salamanders have been observed to remain stationary near odoriferous prey but only feed if it moves. Cave-dwelling amphibians normally hunt by smell. Some salamanders seem to have learned to recognize immobile prey when it has no smell, even in complete darkness.
