Amphibians may include tiger salamanders and toads. Tadpoles of frogs are mostly herbivorous, while tadpoles of salamanders and caecilians are carnivorous. Amphibians also indicate a perennial stream and range from tadpoles, frogs, salamanders, and newts. Adders also feed on amphibians, such as frogs, newts, and salamanders. They eat insects, larvae, earthworms, grubs, rodents, lizards, salamanders, frogs, snakes, birds, moles, and eggs. Amphibians include frogs, salamanders, and the extinct albanerpetontids. Not all aquatic salamanders are considered newts, however. Amphibians are a class of animals comprising frogs, salamanders and caecilians. Modern amphibians (frogs, salamanders, and caecilians) are classified in Lissamphibia. Eggs of some salamanders and frogs contain unicellular green algae. The incidence of albinism in frogs, salamanders, and newts is relatively higher than other taxa. Toads, salamanders and caecilians also use smell to detect prey. Specifically, they have been noted to feed on crayfish, frogs, snails, salamanders and leeches. Caecilians, some plethodontid salamanders and certain frogs lay eggs underground that are unpigmented. Examples include some species of ostracods, small salamanders about in length, and tree frogs.