Swimming is an anguillaform motion of the entire body Several have adapted to life in caves Many are paedomorphic and retain such larval characteristics as external gills, lateral line system, no eyelids, and larval tooth patterns as adults. There forms are fully aquatic. Some plethodontids are completely terrestrial and lay an egg in which the larval stage is completed before hatching. The plethodontids are one of the best known of the salamander families and this groups has some rather interesting specializations. This group of salamanders has lost its lungs.
Respiration is wholly through the skin.
All salamanders lack ribs and thus to get air into the lungs must use a buccal pump, where air is held in the mouth and then compressed to move it into the lungs. This buccal pump uses several muscles that are attached to the tongue. Thus plethodontids had to give up breathing through their lungs so that the tongue muscles could be used to project the tongue instead of pumping air. Their eyes are moved more forward, giving them stereoscopic vision and the nerves from each eye project to both hemispheres of the brain as opposed to eyes more on the sides of the head and the nerves from each eye only projecting to the opposite hemisphere of the brain. The social system of plethodontids has been studied by a number of investigators.