Biology
A number of features distinguish the Plethodontids from other salamanders. Most significantly, they lack lungs, conducting respiration through their skin, and the tissues lining their mouths. Another distinctive feature is the presence of a vertical slit between the nostril and upper lip, known as the "naso-labial groove". The groove is lined with glands, and enhances the salamander's chemoreception.
Adult lungless salamanders have four limbs, with four toes on the forelimbs, and usually with five on the hindlimbs. Many species lack an aquatic larval stage. In many species eggs are laid on land, and the young hatch already possessing an adult body form. Many species have a projectile tongue and hyoid apparatus, which they can fire almost a body length at high speed to capture prey.
Measured in individual numbers, they are very successful animals where they occur. In some places they make up the dominant biomass of vertebrates. Due to their modest size and low metabolism, they are able to feed on prey such as collembola, which are usually too small for other terrestrial vertebrates. This gives them access to a whole ecological niche with minimal competition from other groups.
Read more about this topic: Lungless Salamander
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