Amphibians
Mexican Burrowing Toad
Rhinophrynus dorsalis · also called mexican burrowing toad
The Mexican burrowing toad is the last survivor of a frog family that has otherwise been extinct for tens of millions of years. It lives underground, eats ants and termites through a tongue that fires straight forward, inflates into a squat purple balloon, and after heavy rain fills the night with a call like a moaning whoopee cushion.
Overview
Mexican burrowing toads live in lowland savanna, dry forest, and farmland from southern Texas to Costa Rica, spending most of their lives underground. About 6–8 cm, rotund and loose-skinned with a pointed snout and an orange back stripe, they eat almost only ants and termites.
The last of its family
It is the only living species of the family Rhinophrynidae, over 100 million years old — one of the most evolutionarily isolated frogs alive.
A tongue that fires forward
Where other frogs flip a hinged tongue out and over, this toad shoots its tongue straight forward into ant and termite galleries.
Status
The Mexican burrowing toad is Least Concern, widespread and locally common, appearing in large numbers to breed after heavy rain but rarely seen otherwise.
Mexican Burrowing Toad: common questions
Why is the Mexican burrowing toad important to scientists?
It is the only living species of an entire frog family, the Rhinophrynidae, whose fossil record stretches back more than 100 million years and once included several species across North America. Every other member of that family has gone extinct, so this single, unusual toad is the sole modern representative of a very old and distinct branch of the amphibian family tree. That evolutionary isolation makes it valuable for understanding the deep history and relationships of frogs, and it is one of the reasons the species is sometimes highlighted as an evolutionarily distinct and globally significant animal worth conserving despite currently being common.
How does the Mexican burrowing toad's tongue work?
Almost all frogs have a tongue attached at the front of the mouth that they flip outward and over, unfolding it toward prey, but the Mexican burrowing toad has a fundamentally different arrangement in which the tongue is projected straight forward out of the front of the mouth, more like a mammal's tongue than a typical frog's. This forward-firing tongue, combined with a narrow, pointed head, is well suited to the toad's specialised diet of ants and termites, letting it push its snout into the entrance of an insect gallery and flick the tongue directly down the tunnel to lap up the insects inside.
What does the Mexican burrowing toad sound like?
Its breeding call is one of the most distinctive of any frog, a loud, low-pitched, drawn-out moan or groan that rises and falls, frequently described as sounding like a whoopee cushion or a long, mournful belch. Males produce it while floating at the surface of a temporary rain pool with their bodies puffed up and buoyant, and a chorus of many calling males carries a considerable distance across the landscape on humid nights after heavy rain. Outside these brief, explosive breeding events, which may happen only once or twice a year, the toad is silent and underground.
Why is the Mexican burrowing toad so rarely seen?
The species spends the great majority of its life buried in the soil, often at some depth, emerging only for short, intense breeding episodes triggered by heavy seasonal rainfall that creates temporary pools. Between these events, which can be separated by many months, the toad remains underground, feeding on ants and termites within their nests and waiting out dry conditions in a dormant state. As a result, most people in its range, and even many biologists, have never seen a living one, and the toad is usually detected by its loud call after rain rather than by direct sightings.