Leaping into action

As we leap into the new year, and transition from Spring into Summer, let’s not forget the creatures that epitomise, and possibly invented, the movement of leaping. Evolutionarily, they represent some of the earliest animals to make the transition from water onto land. During their modern-day life cycles, they repeat this ancient feat seasonally. These are the largest type of animal to undergo such radical transformation from their larval stage to adult phase. A process we call metamorphosis. We are talking of course about frogs! In terms of locomotion, many species of amphibian have an incredible ability to cover surprisingly large distances and are supremely adapted to jumping and swimming. Indeed, the earliest known true frog, Prosalirus bitis was suggested to have been a proficient jumper and it is hypothesised that terrestrial jumping was the primitive form of locomotion from which other modes originated.

Frogs are the most species-rich and ecologically diverse group of amphibians, with over 7600 species of frogs and toads, of a total of 8700 amphibian species (the two other groups are Salamanders and Caecilians, none of which occur in South Africa). Frogs are characterised by a unique body plan, usually including long legs, an elongated pelvis, and fused vertebrae, all to assist with the preferred mode of movement – jumping! Modern frogs show a diversity of locomotion modes including hoppers, jumpers, swimmers, burrowers, and arboreal walkers. These different locomotive modes are reflected in different body shapes and adaptations, reflective of their habitat, with burrowing species, for example having much shorter limbs adapted to digging.

The Sharp-nosed Grass Frog Ptychadena oxyrynchus – South Africa’s no1 “jumper”

South Africa’s foremost jumper is the Sharp-nosed Grass Frog, Ptychadena oxyrynchus, and looking at this species you can see why. This animal is ALL legs. It in fact holds world’s record for the longest leap by a frog relative to body size at 10.8 feet (3.3 m). On average, frogs can leap 30 times their body length! That means that if you were a frog, you could jump the length of a rugby field – without a running start. When considered, this is an incredible feat. This ability is advantageous in escaping predators and moving through grassy habitats. The secret to a frog’s jumping skill lies in its tendons. These stretch out while the leg muscles shorten at this point, transferring energy into the tendons. The frog then blasts off as the tendon recoils like a spring. This elastic structure is the key to the frog’s ability to jump long distances.

Can a frog jump out of water? Yes, a frog can jump out of the water. If you have a pond with vertical sides, it can be hard for frogs to get out of the water, and you need to help them a little.

How high can frogs jump? How high frogs can jump depends on the species. Some say frogs can jump at least two times their own height, and the better jumpers (tree frogs, for example) can jump up to 10 times their height. Frogs are much more known for the length of their jump. Can frogs jump backwards? No, frogs cannot jump backwards. The only time that can happen is when they jump from an unstable surface and get flipped over. Otherwise, it just cannot be done.

Taking it to the next level, some frogs can fly. This is because these frogs have webbed toes and use them as parachutes to slow down their fall and glide from one object to the next. While we don’t have any “flying” species in South Africa, one such frog is Wallace’s flying frog (Rhacophorus nigropalmatus), also known as the gliding frog which is a moss frog found in Indonesia and is present in Borneo and Sumatra. It is named for the biologist, Alfred R. Wallace, who collected the first known specimen.

Back on ground, and more locally, the group of southern African frogs known as Rain frogs from the genus, Breviceps, use their short hindlegs and specially modified feet to dig backwards into soil. The species spend most of their time underground and excavate intricate tunnels where they live, lay their eggs and where their tadpoles develop (into the cutest mini rain frogs!). They don’t have a free-swimming tadpole phase and are terrible swimmers!

Bushveld Rain Frog Breviceps adspersus

We have seven species of Rain Frog in KZN, and these are far more commonly heard than seen. They are called Rain frogs as they emerge from their burrows during rain, and call from concealed positions in grassland, and are quite a common garden species. The Plaintive Rain Frog, Breviceps verrucosus, mournful call can often be heard during those misty, rainy spring days we experience in the Upper Highway. Another local underground species is the fascinating Spotted Shovel-nosed Frog, Hemisus guttatus, which unlike the Rain frogs, uses its hardened snout and very stout limps to burrow forward underground. These purple frogs with yellow spots are outlandish, and much of their grassland habitat has been lost to development.

Spotted Shovel-nosed Frog Hemisus guttatus

Another seldom-seen, often heard, ground-dwelling species is the Bush Squeaker, Arthroleptis wahlbergii, that relies on leaf-litter as it’s habitat also has no free-swimming tadpole and is quite common throughout the Durban area. The best thing you can do for this species is: Leave the Leaves! Racking, sweeping and leaf-blowing destroys and dries precious habitat, not just for this species, but many others that share this micro habitat.

Kloof Frog Natalobatrachus bonebergi egg clump

Kloof Frog Natalobatrachus bonebergi in Krantzkloof Nature Reserve

Another supremely adapted local species is the Kloof Frog, Natalobatrachus bonebergi, that occurs only in shaded, rocky streams, including in Krantzkloof and Springside Nature Reserve, as well as Crowned Eagle Conservancy and recently an exciting confirmation of the species at Iphithi Nature Reserve in Gillitts. This species is Endangered due to its restricted range and loss of forested habitat. In Hillcrest our local freshwater health is severely threatened by pollution caused by blocked sewer lines as a result of fats, grease and oil (with the dubious FOGS acronym) from mismanaged restaurant outlets. The Hillcrest, Everton and Kloof Conservancies have joined forces in the Mend-the-Molweni Project to address the sewerage problem and included the Kloof Frog in the project logo. The project team is working exceptionally hard with eThekwini municipality to overcome these issues and have made great progress.

Frogs epitomise environmental health as they are sensitive to change. The Kloof Frog is adept at climbing, swimming, and jumping and is very camouflaged on the stream banks. The species lays distinct egg clumps attached to leaves, twigs and rocks above slow-flowing sections of stream and we can monitor the health of the species, and by proxy, the health of local freshwater systems by counting egg clumps. We hope to see a recovery of the local Springside Nature Reserve population, and ask for your help in this regard:

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