Caecilians, legless amphibians that live under the soil, are perhaps the least well studied of all amphibians. Although they seem primitive, in some ways caecilians are more advanced than frogs and salamanders. They have evolved a method of internal fertilization, allowing them to reproduce without needing a body of water. Like snakes, they possess only one lung, have no legs or external ears, and are primarily insectivorous or carnivorous in dietary habits. They use this lung to breathe, along with cutaneous respiration, which is the term for the ability of many amphibians to breathe through their skin.
Some caecilians are aquatic, but many spend most of their time underground or in the leaf litter, only emerging when it rains. Because they are so secretive and hard to find, it is not surprising that only one caecilian has been recorded as being infected by the chytrid fungus. Caecilians spend a good deal of time in areas that seem to be ideal places for Bd infection, suggesting that infection levels may be higher than has been indicated so far. More research into the biology and natural history of these secretive amphibians is needed in order to determine their conservation status. Even though they are not as charismatic as frogs or salamanders, caecilians form another important link in the chain of life, and these unique species deserve as much respect and protection as any other animal.