(1) While burrowing, caecilians employ concertina locomotion, lateral undulation, and vermiform locomotion.(2) Although they are amphibians, caecilians are denizens of the terrestrial underworld.(3) The oldest known frogs, salamanders and caecilians are very similar to their living descendants.(4) Some not-so-familiar creatures, like the legless, burrowing caecilians , are also amphibians.(5) In contrast to frogs, caecilians have a radically elongated vertebral column, no limbs or girdles, and relatively elaborate hypaxial musculature.