Black rain frog: The bizarre, grumpy-faced amphibian that's terrible at jumping and swimming

Name: Black rain frog (Breviceps fuscus)

Where it lives: The forested slopes of the southern Cape fold mountains, South Africa

What it eats: Small insects 

Why it's awesome: Move over grumpy cat — say hello to the grumpy frog. In addition to being a famous meme, black rain frogs have plenty of unusual traits that make them fascinating critters.

For starters, unlike most other frogs, their chonky round bodies and short, stubby legs make them terrible at swimming and jumping. They are, however, extraordinarily good at burrowing, and spend a large amount of time underground.

"They dig backwards into the ground using their hind feet, which have specialized digging tubercles," Jeanne Tarrant, manager of the Threatened Amphibian Programme at the Endangered Wildlife Trust told Live Science. Using their hindlimbs, they shift the soil by slowly rotating to "disappear below the surface," she said. 

Related: What's the difference between a frog and a toad?

Once there, they create tunnels to form an intricate underground system where females lay their eggs. This has led some to believe they don’t have a tadpole stage, but they do, it just takes place underground, sloshing around the soil rather than swimming in water before emerging from the burrows as froglets. 

Above ground, black rain frogs — which are about 1.6 to 2 inches (4 to 5 centimeters) long — run or walk, rather than hop: "Their legs are very short, and their bodies round," Tarrant said. "They will inflate their round bodies as a predation defense… They do this basically by inflating with air." These frogs also produce a milky substance that is slightly toxic to predators, she added.

So although they may appear grumpy — and have a high-pitched screech to go with their angry faces — we think black rain frogs are pretty cute, especially as the small bumps that cover their body make them look a bit like a tiny avocado.