The Puerto Rican Coquí frog produces a call as loud as a jackhammer.

The Common Coquí (Eleutherodactylus coqui) is a small frog native to Puerto Rico that typically measures only 1 to 2 inches in length. Despite its size, it is one of the loudest amphibians in the world. Research conducted by biologists like Peter Narins at UCLA has shown that at a distance of 0.5 meters, the frog's call consistently reaches levels between 90 and 100 decibels. This volume is comparable to a lawnmower or a jackhammer operating nearby.The call consists of two distinct frequencies: the 'co' note at approximately 1.1 kilohertz and the 'kee' note at 2.1 kilohertz. Male frogs use the lower-frequency 'co' to establish territory and warn off rivals. The higher-frequency 'kee' is specifically designed to attract mates during the nocturnal breeding cycle. This dual-purpose signal allows the frog to communicate two different messages at the same time.A fascinating evolutionary trait involves the auditory system of the females. Studies published in journals such as 'Science' have revealed that the female's inner ear is physically tuned to the 2.1 kilohertz frequency of the 'kee' note. Because their ears lack sensitivity to the lower 'co' frequency, they are effectively deaf to the aggressive territorial displays of the males. This specialized hearing ensures that females can locate a mate without being distracted by the noise of male-on-male competition.