The Amazon Horned Frog (Ceratophrys cornuta), often called the Pacman Frog due to its large mouth and rounded body, is a massive amphibian of the Amazon Basin. This formidable ambush predator uses its sharp teeth and powerful bite force to capture prey nearly its own size. The frog spends most of its life partially buried in leaf litter, utilizing its mottled green and brown coloration as camouflage. Despite its aggressive nature and defenses, the Amazon Horned Frog serves as prey for larger organisms.
Large Reptilian and Mammalian Hunters
The most significant threats to the adult Amazon Horned Frog are predators large enough to overcome its aggressive bite and stocky size. Large constricting snakes, such as the Mussurana (Clelia genus), are adapted to preying on vertebrates. This snake, which can grow to a considerable length, bypasses the frog’s jaw strength by using its powerful coils to subdue the prey before ingestion.
Ground-foraging mammals also pose a threat, as they actively root through the leaf litter where the frog hides. Coatis (Nasua species), which are opportunistic omnivores, are known to consume frogs and other small vertebrates encountered on the forest floor. Their strong forelimbs and long snouts allow them to effectively probe and dig out hidden prey, circumventing the frog’s camouflage. The frog’s tendency to inflate its body and hiss can sometimes deter smaller predators.
Avian and Opportunistic Predators
Predators that attack from above or from the water’s edge often bypass the terrestrial frog’s camouflage. Large raptors, such as forest hawks or the massive Harpy Eagle (Harpia harpyja), are aerial predators. These birds possess acute vision to spot movement in the ground cover and powerful talons to quickly dispatch and carry off the frog.
Opportunistic generalists found near the temporary pools where the frogs congregate for breeding also present a danger. Young spectacled caimans (Caiman crocodilus hatchlings) inhabit the marshy edges of the rainforest and feed on amphibians. As they transition from a diet dominated by invertebrates to small vertebrates, these young crocodilians can ambush adult frogs near the water’s surface.
Targeting Vulnerable Life Stages
The frog’s life cycle includes a vulnerable aquatic stage where the eggs and tadpoles face predation pressure. The tadpoles of the Amazon Horned Frog develop rapidly in temporary pools, but they are subject to a high mortality rate from aquatic invertebrates. These small-scale predators often prove more effective than fish in these ephemeral water bodies.
Several invertebrates prey on the larval frogs:
- The larvae of the Great Diving Beetle (Dytiscus species) are predators of tadpoles.
- Nymphs of large dragonflies also consume tadpoles.
- The giant water bug (Lethocerus genus) nymphs feed on tadpoles and small fish.
These invertebrates use piercing mouthparts to subdue the larval frogs, which lack the size and bite of the adults.