Taxonomically the Caecilians are divided into 5 families. The species numbers have to be taken with care, as many of the species are described after only one specimen. Probably not all species have been described yet, however some of the described different species might turn out to be normal variations inside one species.

Large Caecilians dubbed "ingots" plagued the French occupation of Indochina in the years before the Vietnam war. The creatures were reported to borrow large holes and disrupt troop movement.