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Impurest's guide to Animals #5 – Venezuelan Pebble Toad

Well it’s time for Issue #5 of Impurest Cheese’s Guide to Animals. Last week the ’likely to drive you loony’ Northern Lapwing was in the spotlight. This time we have an animal that rocks and rolls plummeting into the spotlight. Hope you guys enjoy.


Issue #5 – Venezuelan Pebble Toad


Kingdom – Animalia

Phylum – Chordata

Class – Amphibia

Order – Aruna

Family – Bufonidae

Genus – Oreophrynella

Species – nigra

Related Species – The genus Oreophrynella contains nine species of toad all of whom each live on a separate mountain top in South America (1)

Range - The Venuzalan Pebble Toad Lives on a single mountain top on the Venezuelan/Guiana border

Keep low and watch out for falling toads

The Pebble Toad is a small amphibian (growing to 2.5cm long) that lives on a single mountain tops in South America known as a Tepuis (Pemon for Table of the Gods) and has a dark grey colouration to help it camouflage into its natural habitat (2). Unlike most frogs and toads the Pebble Toad is ill adapted to jump and is a poor swimmer as an adult.


Like all amphibians Pebble Toads are carnivorous feeding on invertebrates smaller than itself. They themselves are predated on by birds of prey, larger amphibians and by tarantulas. To defend itself the toad holds its body rigid, pulls its limbs close to its body and simply lets gravity take over and pull it down the slope. Thanks to its small size the Pebble Toad can roll down even the steepest slope and survive without even being harmed (3). Thanks to its dark colouration most would be predators can’t distinguish the difference between a Pebble Toad and a real rolling stone.

Despite its extraordinary escape trick the Pebble Toad is listed as ‘Vulnerable’ on the ICUN Red List. While not directly affected by humanity the Pebble Toad’s mountain top homes are some of the most at risk habitats from global warming. Additionally like most amphibian species the toad is also at risk from a fungal parasite Batrachochytrium dendrobatidis. While no infected individuals have been detected the concentrated population could easily be wiped out if it entered the ecosystem.

Three Fun Pebble Toad Facts

What? Only Three Facts! Since the most impressive thing about the Pebble Toad is behavioural (and because the species remains a bit of a mystery) I have instead included a video of its escape mechanism.

Places to breed on the mountainside are fairly scarce. A small pool can sometimes support up to one hundred toads all trying to breed at the same time. (4)

While defensive curling is a common behaviour in the animal kingdom few species roll to escape predators. Among them is the Mount Lyell Salamander (Hydromantes platycephalus) that forms a ‘tyre’ with its body to roll away from predators

Pebble Toads are some of the most ancient members of the frog family with fossils dating back to fifty million years looking identical to modern species. Additionally recent DNA tests show that the closest relatives of the South American species live in Africa suggesting their origins are even older, possibly even dating back to when the two continents were connected as part of Gondwanaland



(1) –

(2) - Zimmer, Carl. It’s Not So Lonely at the Top: Ecosystems Thrive High in the Sky, The New York Times website, May 7, 2012, and published in the New York edition, p. D3 on May 8, 2012.

(3) –

(4) -

Picture References

[1] -

[2] –

Video Referances

{3} -

Hope you guys enjoyed the insight into this tiny rock and roller. Drop me a comment with an animal you want explored in the next issue.