Of all the creatures that call Puerto Rico  home, none are as beloved as the tiny coqui tree frog, the island’s national symbol. A mere 1–1.5 inches long fully grown, the coqui is difficult to spot, but you can definitely hear the male’s distinctive “co-QUI” call at dusk or after a rain. Despite the ubiquity of their cheerful chirp, of the 16 varieties that live in Puerto Rico, only two make the eponymous sound, which serves to attract a mate and repel reproductive competitors.
Unlike many frogs, the coqui does not have webbed appendages and does not require water to live or reproduce. In fact, coquis are never tadpoles. The female coqui lays its eggs on leaves, and tiny little froglets emerge fully formed from the eggs. Although they’re born with tails, they lose them posthaste.
It is considered good luck to spot a coqui, and there are many other legends surrounding them. One is that a little boy was transformed into a frog because he misbehaved, and now he comes out and sings at sunset. Another involves a bird that was stripped of its wings but was later turned into a frog so it could climb back into the trees where it once lived.
The one creature visitors to Puerto Rico  are sure to spot is a lizard. The island is literally crawling with them, varying in species from the ubiquitous four-inch emerald anoli, which is sure to slip inside the house if a window is left open, to the Puerto Rican giant green lizard, an imposing reptile that can grow up to 16 inches long and lives mostly in the limestone hills.
But Puerto Rico’s mack-daddy lizard is the prehistoric-looking Mona iguana, which grows up to four feet long. Mona Island off the west coast of Puerto Rico is the only natural habitat for the Mona iguana, but there is a tiny mangrove cayo in the bay at La Parguera where a small population is kept for research purposes and which can be seen by boat. Although an herbivore, the Mona iguana has an intimidating appearance because of its horned snout and the jagged bony crest down its back. The Mona iguana lives up to 50 years.
Snakes are few in Puerto Rico, but they do exist. Fortunately, they are all nonpoisonous. The Puerto Rican boa is an endangered species. The longest snake on the island, it grows up to six feet and is quite elusive.