A toad is a type of frog belonging to the family Bufonidae, commonly distinguished by a robust body, short legs, and dry, warty skin. The biggest among all true toads is the Cane Toad, scientifically known as Rhinella marina. This enormous amphibian has gained notoriety around the world not only for its impressive size but also for its ecological impact in regions where it has been introduced.
Identifying the World’s Largest Toad
The Cane Toad holds the title for the largest species within the family Bufonidae. An average adult typically measures between 10 and 15 centimeters (4 to 6 inches) in snout-vent length. Average weight ranges from 500 to 800 grams (1.1 to 1.7 pounds), but females, which grow larger than males, can reach up to 1.5 kilograms (3.3 pounds).
The official record for the largest documented toad was held by a male named “Prinsen,” a pet from Sweden, which weighed 2.65 kilograms (5 pounds, 13 ounces) in 1991. This specimen measured 38 centimeters (1 foot, 3 inches) from snout to vent. More recently, in January 2023, an even heavier wild female toad, nicknamed “Toadzilla,” was discovered in Australia, weighing 2.7 kilograms (5 pounds, 15 ounces), potentially surpassing the long-standing record.
Native Habitat and Global Spread
The native range of the Cane Toad extends across the tropical and semi-arid lowlands of Central and South America. Its distribution spans from the Rio Grande Valley in southern Texas down to the central Amazon basin and southeastern Peru. This terrestrial species is highly adaptable, thriving in open grasslands, woodlands, and areas modified by humans, such as gardens and agricultural fields.
The species is infamous globally as an invasive pest, stemming from deliberate introductions outside its native range. Beginning in the 19th and 20th centuries, it was transported to the Caribbean, the Philippines, Hawaii, and northern Australia. These introductions were primarily intended as biological control to manage agricultural pests like the cane beetle that damage sugarcane crops. The toads failed to control the target pests but rapidly proliferated, destabilizing local ecosystems by competing with native wildlife for resources and preying on smaller species.
Distinctive Physical Traits and Toxicity
The Cane Toad is characterized by a stocky build and dry, tough skin covered in numerous prominent warts. Its coloration is typically grey, yellow, olive-brown, or red-brown, often with a mottled pattern. A distinguishing feature is the presence of distinct bony ridges that run above the eyes and down the snout.
The species’ most notable trait is the pair of large, triangular parotoid glands located behind the eyes and extending onto the shoulders. When threatened, these glands secrete a potent, milky-white substance known as bufotoxin. Bufotoxin is a complex mixture of chemicals, including bufagin and bufotenine, which act as neurotoxins and cardiotoxic steroids. This defense mechanism is an effective deterrent against most predators, as ingesting or licking the toxin can cause severe illness and is frequently lethal to pets and native wildlife.