The “African Bull Worm” is a common, though inaccurate, name for the African Bullfrog (Pyxicephalus adspersus). Native to sub-Saharan Africa, this large amphibian is one of the largest frog species globally, known for its impressive size and robust nature.
Physical Characteristics
African Bullfrogs are large, with males reaching 9.5 to 10 inches (24-25.5 cm) and over 4 pounds (2 kg). Females are notably smaller, typically 4.5 inches (11.4 cm) and half the male’s weight, a unique trait among amphibians. They have a robust, stout build with large heads and wide mouths.
Adults are typically dark olive-green to brown, often with darker markings or textured ridges. Juveniles are brighter green with a distinct yellow stripe. They possess bony odontoids in their lower jaw, functioning like teeth for gripping prey. Powerful hind legs aid in jumping and burrowing; their feet have some webbing, but front toes are stubby and lack it.
Natural Habitat
African Bullfrogs are widely distributed across sub-Saharan Africa, found in countries such as Angola, Botswana, Kenya, Malawi, Mozambique, Namibia, South Africa, Tanzania, Uganda, Zambia, and Zimbabwe. They thrive in moist to dry savannas, grasslands, and semi-arid regions, drawn to temporary or seasonal water bodies like ponds, pans, ditches, and flood plains.
These ephemeral water sources are essential breeding grounds during the rainy season. Despite relying on water for reproduction, African Bullfrogs adapt remarkably to harsh, dry conditions. They also inhabit shallow, vegetated permanent wetlands, utilizing diverse aquatic and terrestrial environments.
Diet and Feeding Habits
The African Bullfrog is a voracious, opportunistic carnivore, consuming nearly anything it can overpower and fit into its large mouth. Its diverse wild diet commonly includes insects, small rodents, birds, reptiles, other amphibians, snakes, worms, and crustaceans.
They employ an ambush hunting technique, waiting partially submerged or concealed in vegetation. Once prey is within striking distance, they launch forward using their powerful hind legs. Their strong jaws, equipped with tooth-like odontoids, grip and consume prey whole. This indiscriminate appetite makes them significant predators within their ecosystems.
Unique Adaptations and Behaviors
African Bullfrogs have specialized adaptations for survival in challenging environments, especially during drought. Their most notable adaptation is estivation, a dormancy similar to hibernation. During dry seasons, they burrow 6 to 8 inches deep, forming a protective cocoon of hardened mucus and shed skin. This cocoon seals the frog, preventing water loss and allowing survival for extended periods, sometimes over a year.
When threatened, African Bullfrogs exhibit several defensive behaviors. They inflate their bodies with air, appearing larger and more intimidating to predators. They also emit loud, bellowing calls, described as croaking, roaring, or bleating. Their powerful jaws and odontoids can deliver a painful bite, serving as an aggressive deterrent.
African Bullfrogs as Pets
African Bullfrogs are popular exotic pets due to their impressive size and unique characteristics. A single adult requires an enclosure like a glass terrarium, at least 20 gallons (60x45x30 cm), with larger males needing a 3-foot long enclosure. Provide a moist, humidity-retaining substrate (e.g., coconut coir, orchid bark, sphagnum moss) for burrowing. A shallow water dish for soaking and waste elimination needs daily cleaning.
Maintain a temperature gradient of 75-85°F (24-29°C) during the day, with a slight night drop. High humidity (60-90%) is ideal, achieved through daily misting. In captivity, their diet primarily consists of gut-loaded insects like crickets, locusts, cockroaches, earthworms, and superworms. Small rodents or “pinkie” mice can be occasional treats, but not a staple diet to prevent obesity. Though generally low-maintenance, their aggressive temperament and powerful bite mean they are not suitable for frequent handling and require caution.