Finding an animal to write about today wasn’t too difficult. I knew it had to be a frog, so I just searched for ‘World’s largest frog’ and had my blog animal. I love it when things are that easy. So today we’ll talk about the biggest extant frog in the world, the aptly named goliath frog.
We know goliath frogs are big, and now we get to find out just how big that actually is. They range in size from 17 to 32 cm, and can weigh up to 3250 g. That is pretty big for a frog. I know I would be quite startled if I stumbled across one casually hopping around a rainforest. Goliath frogs have greenish brown skin on their backs, with lighter colouration on their underbellies. They have fully webbed feet, and look very much like a typical frog.
Goliath frogs have a limited distribution, being restricted to areas within Cameroon and Equatorial Guinea. They like hot and humid areas, and therefore are usually found in rainforests. As frogs, these guys are fond of water, and so are live near or in rivers or waterfalls. The water they prefer is fast flowing, clear, and highly oxygenated.
Goliath frogs differ from many other types of frogs in that they do not have a vocal sac. This means that goliath frogs cannot call to advertise their readiness to mate, as most frogs and toads generally do. Instead, male goliath frogs make whistling noises, which attract nearby females. Males ready their mating area by carefully arranging stones into semicircular patterns. After mating, females lay several hundred eggs in rivers or streams. The eggs stick to vegetation in the water and hatch shortly after into tadpoles.
Surprisingly, goliath frog tadpoles aren’t that much larger than those of other frogs. They just grow really, really fast. Most of this growth occurs during the first 75 to 90 days of life. The little tadpoles feed on vegetation, specifically Dicraeia warmingii. This aquatic plant is only found in fast moving water, such as those around waterfalls and rapids. Such a specific diet may help explain the goliath frogs’ very limited range, as areas without Dicraeia warmingii would be uninhabitable for goliath frog tadpoles.
Adult goliath frogs don’t have the same problem: their diet is much more varied. They can chow down on various insects, crustaceans, fish, small mammals and amphibians. They themselves don’t have a lot of predators, thanks to their size and colouration. The green skin colour of goliath frogs helps them blend in with mossy rocks that are common in their habitats. They aren’t completely safe, however, as they have been known to fall victim to Nile monitors, Nile crocodiles, and snakes.
The most dangerous predator to goliath frogs, however, is humans. The frogs are considered a food source in some areas, and are also exported for the pet and zoo trade. Goliath frogs do not do super great in captivity, and very rarely breed there. So we have to get all captive goliath frogs from wild populations. This has put a severe strain on the species, and it is now listed as endangered. There is some protection for the species in the wild, but habitat destruction and collection for pets are still putting pressure on them. Poor frogs!