The term “horned frog” refers to the terrestrial amphibians of the genus Ceratophrys. They are often called Pacman frogs due to their disproportionately large, circular mouths. These large, stout-bodied frogs are formidable ambush predators. They should not be confused with the Texas Horned Lizard (Phrynosoma cornutum), a spiky-bodied reptile found in North America.
Geographic Distribution of the Horned Frog Genus
The entire genus Ceratophrys is endemic to South America, with its distribution spanning a wide range of tropical and subtropical environments. Their collective range covers numerous countries, extending from the Amazon basin in the north down to the Pampean region of Argentina in the south. This vast area includes Brazil, Argentina, Paraguay, Uruguay, Bolivia, Colombia, Ecuador, Peru, and Venezuela.
The genus occupies diverse climate zones, adapting to environments ranging from humid rainforests to semi-arid scrublands. They are generally found in lowland areas, though some populations inhabit elevations up to 700 meters above sea level.
Specific Terrestrial Habitats and Adaptations
Horned frogs are terrestrial and fossorial, meaning they spend the majority of their lives on the ground or partially buried. They prefer loose substrate, such as leaf litter, soft soil, or mud, which facilitates burial. They employ a characteristic “sit-and-wait” predation strategy, camouflaging themselves by sinking into the ground with only their eyes and horn-like projections visible.
These amphibians require environments with high moisture and stable temperatures to support their skin’s respiratory function and prevent desiccation. Typical habitats include moist forest floors, humid grasslands, and areas near temporary water sources like ephemeral ponds or drainage ditches. In drier regions, such as the Gran Chaco, species like Cranwell’s Horned Frog enter a state of estivation during the dry season. They conserve moisture by creating a hardened cocoon of shed skin while buried deep underground until seasonal rains return.
Regional Distribution of Key Species
The different species within the genus are separated by specific geographic boundaries, reflecting their adaptation to distinct regional biomes. The Argentine Horned Frog (Ceratophrys ornata) is primarily found in the temperate grasslands of the Pampean region. Its range covers central and northern Argentina, Uruguay, and the southernmost tip of Brazil, thriving in subtropical grasslands near temporary bodies of water.
Cranwell’s Horned Frog (Ceratophrys cranwelli) is endemic to the drier, semi-arid environment of the Gran Chaco region. Its range extends across northern Argentina, western Paraguay, eastern Bolivia, and parts of Brazil, where it is adapted to the seasonal extremes of dry forests and scrublands. The Surinam Horned Frog (Ceratophrys cornuta) inhabits the humid tropical rainforests of the Amazonian basin. Its distribution includes northern Brazil, Colombia, Ecuador, Peru, and the Guianas, where it resides on the leaf-littered floor of old-growth forest areas.