Desert Rain Frog Profile
Amphibians are generally known to ecologists as sensitive animals. Their narrow tolerances to environmental conditions make them prone to struggles sooner than many other animals when these conditions change.
This makes them useful as indicator species, as canaries in a coal mine, showing the health of the ecosystem. In some ways, the desert rain frog defies this sensitivity – able to tolerate arid environments. But in others, it’s just as specialised and vulnerable to human impacts on its habitat.
The desert rain frog or web-footed rain frog is a rather plump species of frog found in the sand dunes of Namibia and South Africa.
Desert Rain Frog Facts Overview
|Sandy shores and dunes
|Namibia and South Africa
|Up to 14 years
|Up to 6cm (2.5 inches)
|Moths, beetles, larvae
|Snakes, scorpions, rodents
|5 kph (3 mph)
|No. of Species:
Often touted as the world’s cutest frog, this bulbous little screamer looks and sounds like a sticky Pokemon and even defies the true meaning of the word amphibian.
They grow to around 4 to 6 centimetres (1.6 to 2.4 in) long and have a yellow-brown color, that matches the sand dune that they inhabit.
Desert rain frogs are nocturnal, and spend the daytime burrowed in the sand to avoid the blistering heat of the sun. At night, they will emerge to feed by hunting for insects, such as moths, termites, beetles and insect larvae.
They are highly specialised to desert environments and can do things that most other animals in their class can’t.
Unfortunately, consumer demand for an arbitrary display of wealth yet again threatens the habitat of a unique species and these little frog balls may soon be in serious trouble.
Interesting Desert Rain Frog Facts
1. They skip tadpoles, straight to froglets
Desert rain frogs have quite unusual abilities for amphibians. Not least of which is the way they reproduce. Upon hearing the characteristic mating wail of a male frog, a female will approach and the two will burrow into the sand to mate.
The female will lay between 12 and 40 eggs, which, unlike most frogs, will hatch as fully-formed froglets, conveniently skipping the tadpole stage, since there’s no fresh water around for them to live in, anyway.
These froglets are immediately independent and quickly get on with their lives, hunting for food. 1
2. They are one of the only frogs that don’t lay eggs in water
One of the key features of a so-called amphibian is its reliance on an aquatic stage for development. That’s what differentiates it from terrestrial or aquatic vertebrates, which live either on land or in the water, and don’t try to make things overly complicated.
Amphibians classically have a larval stage with gills for breathing underwater, and gradually make their way onto land as they morph into mature adults. In most textbooks, this will be a defining characteristic: amphibians need a water body to breed.
The desert rain frog, as with other members of the Breviceps genus, never got this memo, and despite being an amphibian, has evolved to replicate the reproductive strategy of the amniotes – land vertebrates who use a protective egg case to contain the necessary fluid for the development of their young so that they can live exclusively on land.
These frogs don’t form a rigid shell for their eggs, but instead, produce a thick mucous layer to the same effect.
(Shoutout to the axolotl, who went the other way and decided never to leave the water.)
This doesn’t declassify them as amphibians, it just gives pedants more ammunition to interject with “well actually…” and reminds us that there are no absolutes in nature.
3. Desert rain frogs have weird feet
Since they’re not spending any time in the water, Breviceps frogs adapted to living on the land. They have some very curious traits in this regard.
Most of them live in burrows (which is known as being fossorial), which has led to them shedding the webbing on their hands, making them more suited for digging.
Since the desert rain frogs live on sand, however, they’ve developed extensive, specialised webbing that makes them stand out from their cousins.
4. They can’t hop
Another unusual trait for a frog, is that it can’t jump or hop around like a typical frog – which can make it challenging when escaping predators.
It has a plump body, with small legs, which makes leaping difficult. Instead it walks around on the sand, leaving behind small frog footprints.
5. They have deeply wrinkled, pendulant sacs, maybe?
But probably not where you’d expect. These sacs sit under the head of the male and are inflated with air to resonate loud calls. Seemingly, only the male makes these calls, and at least in other species, they’re made both as a mating gesture and a threat.
This is supposedly one of the characteristics that helps tell males from females in rain frogs, and while described as “deeply wrinkled” and “pendulant” in the 1970s, contemporary images make this description a little dubious. 2
6. Absorbent bellies
The desert is the most unlikely place to find a frog. Without so much as a significant shower throughout the year, rain frogs need to make do with the 60mm annual precipitation, most of which comes in the form of fog.
They survive by absorbing moisture from the fog itself and from the sand that it collects on, and they do this through thin membranes on their bellies.
They also dig down into the sand during the day to access the deeper moisture and avoid the arid heat of the sun, coming out at night to feed on termites and other invertebrates.
7. They’re sticky
One commonly-overlooked handicap of leaving the water is the loss of buoyancy. When a daddy loves a mummy frog very much, traditionally they jump on her back and float around together, causing her to lay eggs in the water. With the bulk of the enormous female supported under the surface, the much smaller male just needs to hold on as she goes around filling the pond with frogspawn.
Since rain frogs breed on land, they’re not aided by this buoyancy and instead have developed a sort of sticky Velcro system, in which the front side of the male and the back side of the female have corresponding stickiness.
This allows them to glue together, and aid in laying eggs underground. 3
8. They squeak!
Despite being ugly as a melted welly, these small, almost spherical frogs have gained popular appeal due to their tiny and unnerving scream.
This is likely a product of someone stressing the animal for the camera, so it’s not something to encourage, but there is a cuteness that comes from an animal so tiny being so furious.
The desert rain frog uses it’s distinctive squeaking sound during breeding season, where it will emerge from their underground burrows at night and call out to females.
9. You can see their internal body organs
On the underwide of the desert rain frog, they have a transparent patch of skin through which its internal organs can be seen.
This is something that can also be seen in glass frogs, which is thought to aid them when hiding from predators.
10. They could be at risk
Despite occupying an area of land that’s only 2,000 km2 (770 sqm) these are little-known frogs that have only recently become popular in the public eye. And despite being particularly resilient to the arid and relatively inhospitable environment of the dunes, they’re highly specialised, and therefore have very low tolerances.
Diamonds are a functionally useless and artificially inflated chunk of carbon that many people seem to enjoy. Sadly, mining operations for this worthless, shiny gravel are fragmenting and destroying much of the habitat of many species of Breviceps, the rain frog included.
This has led to the IUCN’s classification of B. macrops as near threatened, though much more information is needed. With a small habitat range and not much attention from the conservation world, these glorified dog toys may quietly disappear. 4
Desert Rain Frog Fact-File Summary
Fact Sources & References
- Hendrik Müller (2007), “Reproduction in Brevicipitid Frogs (Amphibia: Anura: Brevicipitidae)—Evidence from Probreviceps M. Macrodactylus“, ResearchGate.
- (1978) “LIST OF MEMBERS“, The Journal of the Herpetological Association of Africa.
- J Visser (1982), “The histology of dermal glands of mating Breviceps with comments on their possible functional value in microhylids (Amphibia: Anura)“, African Zoology.
- Alan Channing (2001), “Threatened amphibians in the Succulent Karoo Hotspot: An integrated approach to their conservation“, University of the Western Cape.