Judge us for it if you must, but we can't resist a good story about the animal kingdom's weird and wonderful mating rituals (we made this show, after all). And besides, how can you not be fascinated by the bizarre biology and millions of complex behaviours that have evolved to allow the planet's species to spawn the next generation? Which brings us to this guy. The second-largest frog on the continent, the African bullfrog has mating habits that are both fascinating and just a little scary (and not for the squeamish).
But don't take our word for it. Here's the bullfrog mating ritual explained by someone who's filmed and photographed it in the wild:
Meet the heavyweight champion of the southern African frog world. Some would describe him as beautiful ... others, not so much. A fully grown adult male can weigh in at a staggering one kilogram. Put your two hands together side by side and you'll get an idea of just how big he is.
As adults, African bullfrogs forage and feed in open grasslands, devouring pretty much anything that moves and will fit inside their jaws: rodents, snakes, birds (yes, birds), lizards, other frogs ... the list goes on. (Scary fact: the width of their mouths allows them to swallow mice whole.) They're armed with two bony projections (odontoids) that look like teeth on the lower jaw, which are used for gripping prey and self-defence during territorial disputes. In captivity, they've been known to live for as long as 14 years. African bullfrogs are scary beasts.
When the first good rains of summer arrive, the frogs will emerge from the depths of the earth (where else would such scary creatures overwinter?), shedding their old, dead skins. And that's when all the fun begins. Mating becomes the primary objective. Territories in a pan are established and protected in ferocious battles. The males start calling from within the shallows with a very deep, three-second 'woop', which vibrates the water around their vocal sacs.
Females approach cautiously and, once spotted, are caught and held in an amorous embrace known as the axillary amplexus. They're protected as any prize possessions would be, and a male will spend a lot of his time fighting off less fortunate rivals that hang around hoping for an opportunity to sneak in.
And here's where things start to get a little uncomfortable for the (much smaller) females. Being about a third of the size of her partner, a female finds herself trapped beneath his considerable bulk.
Mating takes place in fairly shallow water, and when the female is ready to lay eggs (which she does regularly in batches of hundreds), she straightens her legs, lifting her hindquarters into the air. The male immediately responds to this signal by lowering his head into the water ... and almost drowning the female under him in the process. Drowning risk aside, this enables him to raise his own hindquarters up to cover hers, and when the eggs are released, he can fertilise them without hesitation while out of the water, which probably improves fertilisation rates. This process is repeated multiple times, and thousands of eggs are laid into the warm shallows.
It all looks something like this (a little warning from the editor: we're pretty sure this is NSFW):
Once the deed is done, the female wanders off – and it's the male who remains in the territory to protect the young tadpoles until they are able to hop away. Speed is key here – the pan could dry up at any time. The eggs develop extremely quickly and will hatch within 36 hours, growing rapidly. Metamorphosis is complete after around 20 to 33 days. And the fearsome bullfrogs make surprisingly doting dads: there is documented evidence of males digging canals from one pool to another to prevent the tadpoles from becoming trapped in a drying pool.
Once his fatherly duties and the reproductive cycle are complete, the male will dig himself back down into the soil using his strong back legs to await the next year's rains ... and another round of romance.
