Colours of Wildlife: Ornate Frog
Created | Updated Feb 16, 2014
Ornate Frog
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
Time to feature another froggie! This is the Ornate Frog, Hildebrandtia ornata. It is named for its conspicuous ornamentation: most of them have bold black bands and blotches decorating their backs, with lighter, mottled bellies. Actually this is another species of frog that is extremely variable. The ground colour can be green, reddish, brown or golden-yellow; some of them are very pale, with a creamy or whitish ground with brown blotches. These colour variations can occur in the same population; ornate frogs can change colour as they grow older.
Ornate frogs are rarely seen and not much is known about them. They spend most of their lives underground, in a kind of torpor. They only come out during warm, rainy weather. Since they live in the savannah regions of sub-Saharan Africa, this happens in the spring and summer, which is also when they breed. The male ornate frog has two separate vocal sacs, one at each corner of his mouth. When not in use they withdraw into a pair of slits just below the frog's jawline. The call of the courting male is a short, rather nasal quack, repeated frequently and for very long periods. Calling males are extremely hard to find … they probably call from inside burrows at or close to the edge of a seasonal pond or pool. (They've also been found breeding in temporary rock pools on top of the small, isolated rocky hills we call 'koppies'.) When a receptive female approaches, the male comes out and grasps her under the armpits, a move particular to amphibians which is called 'amplexus'. The male frog develops hard ridges on his forelimbs, called nuptial pads, to hold her more securely. She will lay her eggs into the water, and he fertilizes them as they come out. This frog lays its eggs singly and widely scattered, rather than in clumps or in strings like some other toads and frogs do.
The tadpoles of the ornate frog are fairly large, compact and muscular. A very distinctive feature in most ornate frog tadpoles is that they have a metallic glimmer. They are predatory, and will eat anything that falls or lives in their pools, including other tadpoles. They have horny jaws with projecting prongs on their lower 'lips'. In the laboratory they've even been seen eating their own kind, but this might be due to their living in unnatural circumstances. In nature the tadpoles grow quickly and metamorphose into 20-mm/0.8"-long frogs after about three weeks.
Young ornate frogs are somewhat more slender than adults. Adult frogs are pudgy and compact, quite toad-like in form. Nevertheless, they are true frogs, either classified in the river frog family or in the grass frog family. They can be confused with young bullfrogs but most of the time their markings are bolder. In particular, ornate frogs have a distinctive pair of whitish, Y-shaped stripes down the length of their throats. They reach a snout-to-vent length of about 65 mm/2.5". The squat body shape is typical of frogs that bury themselves in the ground. They often make their burrows under logs or stones. When the rainy season starts, they come out and eat to prepare for breeding. The adult frogs are predatory and will catch invertebrates as well as smaller frogs. They particularly like the winged male and female termites, called alates, that also emerge to breed at these times. When confronted, ornate frogs will puff their bodies up and lift themselves high on their legs to appear as large as possible. These frogs are apparently not particularly poisonous, since there are African rural peoples that regularly eat them. Despite this, they are not endangered, and have a very wide distribution in sub-Saharan Africa.
