Desert Rain Frog
The desert rain frog is one of the most unusual and entertaining amphibians on Earth. It lives only in a narrow coastal strip of sand dunes in the Namib Desert of Namibia and South Africa. Round, googly-eyed and grumpy-looking, this small frog became internet-famous for its tiny squeak (more like a squeaky toy than a frog's croak) when threatened. Unlike most frogs, it does not need standing water to breed.
- Where it livesNamib Desert coastA narrow strip in Namibia and South Africa
- LengthOnly approx. 4 to 6 cmSmall, round and ball-shaped
- Famous forIts tiny squeakSounds like a squeaky toy
- HabitatSand dunes near coastSurvives on fog moisture
- BreedingNo water neededLays eggs in damp sand
- StatusNear ThreatenedLimited to a small habitat
How small is the desert rain frog?
The desert rain frog is small (about the size of a golf ball) but not the smallest frog. It is famous more for being almost spherical than for being tiny.
What is the desert rain frog?
The desert rain frog (Breviceps macrops) is a small round amphibian in the family Brevicipitidae (the "rain frogs" or "short-headed frogs"). It is shaped almost like a ball, with stubby legs, a flat face and bulging eyes. The skin is mottled tan-brown to match the desert sand. Adults reach approx. 4 to 6 cm in length, with females being slightly larger than males.
A frog in a desert?
Most people are surprised to learn that any frog could survive in a desert. Frogs need moisture to keep their skin from drying out, and almost all frog species need standing water (a pond, lake or stream) to lay their eggs in. The desert rain frog has solved both problems in remarkable ways.
To stay moist: the frog lives along the Atlantic coast of the Namib Desert, where cold ocean water cools the air and produces regular night fog. The frog burrows down a few centimetres into the sand during the day and absorbs moisture from the fog-dampened sand. Its skin can absorb water directly from damp sand, much like a sponge.
To breed without water: instead of laying eggs in water, the female lays a small clutch of eggs in damp sand. The eggs develop directly into tiny frogs without ever going through a free-swimming tadpole stage. The new frogs are essentially miniature adults from the moment they hatch.
The famous squeak
When threatened, the desert rain frog has a defensive display so unusual it became one of the most famous animal videos on the internet. The frog inflates its body like a balloon (making itself look bigger and harder to swallow) and emits a high-pitched squeaky cry that sounds almost like a child squeezing a dog toy. The squeak is meant to startle and confuse predators long enough for the frog to escape.
The frog has no fangs, no venom and no real defences except its squeak and its puffiness. It would not last long against a determined predator, but small desert predators (like sand foxes or small owls) are often confused enough by the unexpected behaviour to back off.
The challenge of conservation
The desert rain frog's entire habitat is a narrow coastal strip approx. 10 km wide and 1,400 km long, running up the Atlantic coast of Namibia and South Africa. Coastal development, diamond mining (the strip overlaps with one of the world's richest diamond-mining areas), and off-road vehicle traffic all threaten the frog's tiny habitat. The species is now classified as Near Threatened on the IUCN Red List. Most of its remaining habitat is protected as part of the Sperrgebiet ("Forbidden Zone") in Namibia, a restricted diamond-mining area that has been largely closed to the public and therefore relatively intact ecologically.
Deeper dive: direct development, the Sperrgebiet, and the fog-dependent ecosystem
Direct development (skipping the tadpole stage and going straight from egg to froglet) is a relatively rare strategy among the world's 7,000 or so frog species, but it has evolved independently multiple times in different families. Direct development is especially common in frog species that have moved away from standing water as a breeding habitat: rainforest frogs that lay eggs on leaves, mountain frogs that lay eggs in damp moss, and (in the case of the desert rain frog) desert frogs that lay eggs in damp sand. The advantage is that the species is no longer constrained by needing water bodies for tadpole development; the disadvantage is that direct development requires laying larger, yolk-rich eggs (which are more energy-expensive for the mother to produce) and producing fewer offspring per clutch. The desert rain frog has taken this trade-off to an extreme.
The Sperrgebiet ("Forbidden Zone" in German) in Namibia, where most desert rain frog habitat lies, is one of the most unusual conservation zones in the world. The 26,000 km² zone was closed to public access in 1908 by the German colonial government after diamonds were discovered in the coastal sands. For over 100 years, the zone was effectively a no-go area patrolled by armed guards. The closure preserved the natural environment by accident; almost no roads, settlements or commercial activities other than diamond mining were allowed. In 2008 most of the Sperrgebiet was redesignated as the Tsau //Khaeb National Park, opening selected parts to limited tourism while continuing to protect the rest. Many endemic species (including the desert rain frog) survived only because of this accidental century-long protection.
The narrow coastal Namib ecosystem in which the desert rain frog lives is one of the most unusual ecosystems on Earth, almost entirely dependent on fog rather than rain. The cold Benguela Current along the Namibian coast cools the air over the ocean, producing dense fog banks that drift inland at night, sometimes penetrating up to 50 km from the coast. The fog deposits enough moisture to support a unique community of plants and animals adapted to fog rather than rain. Other famous Namib fog specialists include the welwitschia plant (which absorbs fog through pores in its leaves), the fog basking beetle (which collects fog water on its back), and lichens that grow on rocks and gain their water entirely from fog. The desert rain frog is part of this remarkable fog-dependent ecosystem.
The home desert is the Namib Desert. For other desert animals, see desert animals.