Written by Ben Coley from Bushwise
Nature is full of weird and wonderful designs but perhaps one of the hardest done by in terms of aesthetics is the unfortunate bushveld rain frog (Breviceps adspersus). The tourism industry has rather cruelly decided on an ‘Ugly 5’ (warthog, blue wildebeest, spotted hyena, marabou stork and lappet-faced vulture), but the bushveld rain frog is undoubtedly a glaring omission!
Despite looks that only a mother could love, it sports an impressive array of adaptations that are unique to this family.
Here are two great examples of these adaptions:
Stick like glue
One of the most unusual aspects of this charismatic hopper is its odd mating behaviour. In ecology, a lot of emphasis is put on an organism’s ecological niche, i.e. what it does specifically in comparison to other similar organisms. This is a great way to alleviate competition. For most people, when asked about the mating rituals of frogs, we all think about frogspawn – the gelatinous lumps of eggs floating in ponds; but if every species did this, there would be so much competition for space and food for the tadpoles that not all would survive.
Even before we discuss the bushveld rain frog’s novel approach to this problem, we need to go back to the beginning, where fertilisation takes place. The act of copulation in frogs is known as amplexus, where the male grasps the female and the two engage in release of sperm and eggs in a process of external fertilisation. This remains the same in bushveld rain frogs, but due to their somewhat rotund appearance, clasping is not always possible!
They have therefore come up with a novel way to deal with this potentially embarrassing problem known as ‘adhesion’. As the name implies, the male literally glues himself to the back of the female with secretions from their skin. This innovative approach ensures that he does slip off and allow another male the opportunity to share the spoils! So strong is this connection, that should someone try to separate them, their skin would literally tear!
When the time comes to disengage, the female releases a solvent from the pores on her back that removes the adhesive effect and the frogs can go their separate way.
Rather than deposit the eggs in water like most frogs, the amplectant pair burrow into the soil and lay the eggs in a small chamber. There is thus no true tadpole stage, as the young develop within the safety of their jelly cocoon, without the need for water, ultimately metamorphosing into tiny froglets before emerging from their nest to venture off into the big wide world.
A frog-shaped balloon
This world, though, is full of danger. Frogs are a favourite snack for a variety of other animals, but due to their burrowing habits bushveld rain frogs are not designed for speed – and therefore cannot make a swift escape! They have stumpy legs and a globose body that allows them only to comically waddle as opposed to hopping to safety. Their first defence is simple camouflage, utilising cryptic colouration to blend into the environment.
However, if this is unsuccessful, they have a rather unique (and amusing) plan B: rain frogs are able to blow themselves up to about double their original size in order to intimidate a predator and seem much larger. This has led to the Afrikaans name ‘blassop’, meaning ‘to puff up’.
This adaptation among all others is perhaps their most noticeable. If anyone has ever seen a puffed up rain frog, they will know what I mean here. Envision a large frog-shaped balloon with little legs dangling from the corners and you are close to the overall effect. Add this extreme bloating to their comical down-turned mouth and flattened face and you’ll have something bordering on the hilarious!
Despite their wacky appearance, rain frogs are an integral part of the environment, playing a major role in controlling insect populations and their numbers act as an environmental indicator (as with all frogs, their ability to ‘breathe’ through their skin renders them susceptible to pollutants and toxins). These and other adaptations make them a welcome addition to any game drive and the environment!
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