Amphibians belong the phylum Chordata, subphylum Vertebrata, and class Amphibia. The class Amphibia, which contains more 7,000 species, is comprised of three extant (or currently existing) orders; Anura (the tailless amphibians, specifically frog and toads), Caudata (the tailed amphibians, specifically salamanders, newts, sirens, and amphiumas), and Gymnophiona (the limbless and principally subterranean amphibians known commonly as caecilians, which have a physical appearance similar to earthworms).
The order Anura makes up the bulk of the diversity of living amphibians, with more than 6000 species. The Order Caudata is the second most diverse group of living amphibians with nearly 700 species, followed by Gymnophiona with 200 species.
Costa Rica’s 199 species of amphibians are represented by all three know living orders, with 143 species of anurans (72 % of total diversity), 49 species of caudates (24 % of total diversity), and 7 species of caecilians (4 % of total diversity).