The Ghost Frog

May 14, 2012

I’m not really into frogs. I love their croaking – especially in misty conditions on the mountain, when it lends an air of mystery to the landscape – but otherwise I am not particularly impressed by them. That all changes when it comes to Heleophryne rosei, commonly known as the Table Mountain ghost frog, one of 19 frog and toad species on the mountain.

So what makes the ghost frog so special?

Primarily, its distribution: it lives only in the swift-flowing sections of seven perennial streams on Table Mountain (all on the south and east side), nowhere else on earth. That’s an area of about eight square kilometres. One of only two vertebrates endemic to the Cape Peninsula (the other also a frog), the ghost frog can truly be called a child of Table Mountain.

Heleophryne (Latin for ‘the one who is afraid of the sun’) rosei is one of the most ancient frog species, having split off from its closest ancestors more than 160 million years ago. Its solitary evolution on Table Mountain spans millions of years and gave it the niche habitat of swift-flowing streams by endowing it with suction pads on their toes, tiny skin projections that grip like Velcro, flattened bodies and highly webbed feet. Even the tadpoles are adapted to life in the fast lane, possessing sucker-like mouthparts that prevent them from being swept away by the current.

One of the coolest things about ghost frogs is their translucent belly through which the innards can be seen. This together with its scarcity and secretive nature accounts for its name. In fact, you’re almost more likely to come across a real ghost on Table Mountain than one of these guys. Two decades of hiking the mountain and I’ve only ever chanced upon one. They spend much of the day underwater, ensconced in crevices, only emerging at night to feed on insects.

So how will you recognize one?

If you find yourself along a fast-flowing stream on the south or east side of Table Mountain at dusk – or at night with a headlamp – and you come across a frog five to six centimeters long with enlarged toes and a striking skin coloration (pale green with purple spots) perched streamside on a mossy rock, then you’re most likely looking at a ghost frog. Congratulations. However, non-breeding adults occasionally do stray from streams and venture into bogs and caves.

Sadly, the ghost frog is set to become even more elusive, and might even face total extinction.

Tadpole numbers in Skeleton Gorge (one of its habitats) have dropped by an estimated 50% since 1980. Not surprising that it’s listed as Critically Endangered. With an area occupancy of less than 10 square kilometers and a continuing decline in the extent and quality of its habitat, extinction is a very real possibility. In fact, it has already become extinct in some parts of the mountain. The main threats are the spread of invasive alien (non-indigenous) vegetation, frequent fires and reservoirs (affect the consistency of stream-flow). Furthermore, poor forestry practices also contribute to the clogging of streams.

On a brighter note, Table Mountain National Parks is committed to the eradication of alien plants on the mountain – an ongoing programme that will benefit not only the ghost frog, but many other native plant and animal species.

We at Hike Table Mountain actively involve ourselves in the fight against aliens (of the terrestrial kind!) through the cutting down of cluster-pines (saplings), one of the most invasive aliens on the mountain. Please feel free to contact us should you wish to join our next outing.