One of the principal sources of Costa Rica's biodiversity is that the country, together with the land now considered Panama, formed a bridge connecting the North and South American continents approximately three to five million years ago. This bridge allowed the very different flora and fauna of the two continents to mix.
Costa Rican butterflies and moths have made amazing adaptations to the environment. Some examples of these are the following:
Ecotourism is one of Costa Rica’s primary economic resources, and the country's butterflies add a lot to that. They bring life to rainforests, not only with the diversity in colour, but with the magnificence of the flowers that they help pollinate.
Some common butterflies and moths in Costa Rica include:
Costa Rica is home to around 175 amphibians, 85% of which are frogs. Frogs in Costa Rica have interesting ways of finding fishless water to raise their young in. Fish, of course, will eat tadpoles and eggs. Poison Dart Frogs put their eggs in water pools in bromeliads. Other methods include searching ponds before laying eggs, and laying eggs in wet soil. There are 35 species of Elutherodoctylus frogs, 26 species of Hyla frogs and 13 species of glassfrogs.
Notable frog species in Costa Rica include Red-eyed Tree Frog , a few species of Poison Dart Frogs, the semitransparent glassfrogs, and the large Smoky Jungle Frog. Some other notable toad species in Costa Rica include the ten species of Bufo toads, and the Giant toad a huge toad known for its wide appetite. It has been documented eating almost anything, including vegetables, ants, spiders, any toad smaller than itself, mice, and other small mammals.
Besides the frog species, approximately 40 species of lungless salamander and two species of caecilian are found in the country, both rarely-seen and little known. Costa Rican amphibians range in size from the Rainforest Rocket Frog, at 1.5 cm (0.5 in), to Giant toad, at up to 15 cm (6 in) and 2 kg (4.4 lb).
Approximately 225 reptiles are found in Costa Rica. This includes over 70 species of lizards, mostly small, forest-dwelling anoles. Large lizards such as basilisk and Green iguanas are probably the country's most regularly-encountered reptiles. Snakes number about 120 species in the country, including 5 powerful boas and a wide diversity of harmless colubrids. There are about 20 venomous snakes, including colorful coral snakes and various vipers such as the common eyelash viper and two formidable, large bushmasters. The venomous snakes of Costa Rica are often observed without issue if given a respectful distance. Among turtles, 5 of the world's 7 species of sea turtles nest on the nation's beaches. Two crocodilians, the widespread Spectacled Caiman and the large, sometimes dangerous American Crocodile are found in Costa Rica. The country's reptiles range in size from the delicate 15 cm (6 in) Hallowell's Centipede Snake of the Tantilla genus to the hulking Leatherback Turtle, at 500 kg (1100 lb) and 150 cm (60 in).
Costa Rica is home to nearly 250 species of mammal. Medium-sized forest-dwelling mammals are often the most appreciated mammalian fauna of country. These include monkeys such as the frantic White-headed Capuchin and noisy Mantled Howlers; two species of aptly named sloths; the opportunistic White-nosed Coati; and the fierce predator, the Tayra.
Bats comprise more than half of the mammal species in the country, unusually outnumbering rodents twice over. Their bats are adapted to various foraging methods and foods; including nectar, fish, insects and parasitized blood, as the case with the infamous vampire bats. Prominent bats include the tiny, communal-roosting Honduran white bat and the huge, predatory Spectral Bat, the largest new world bat. Large fauna, such as tapir, jaguar and deer are rarely encountered, being both elusive and tied to now-fragmented undisturbed habitats. Costa Rican mammals range in size from the 3-gram Thumbless Bat of the Furipteridae family to the 250 kg (550 lb) Baird's Tapir.
Anteaters are common in lowland and middle elevation throughout Costa Rica. The most commonly seen of Costa Rica's three anteaters species is the lesser anteater (or tamandua locally). The giant anteater is hug, is in endangered. The other anteater is the silky snteater.
894 bird species have been recorded in Costa Rica (including Cocos Island), more than all of the United States and Canada combined. More than 600 of the Costa Rican species are permanent residents, and upwards of 200 are migrants, spending portions of the year outside of the country, usually in North America. Seven of the Costa Rican species are considered endemic, and 19 are globally threatened. Costa Rica's birds range in size from the Scintillant Hummingbird, at 2.2 grams and 6 cm (2.4 in), to the huge Jabiru, at 6.5 kg (14.3 lb) and 150 cm (60 in) (the American White Pelican is heavier, but is an accidental species).