The Cane Toad (Rhinella marina), also known as the giant neotropical toad or marine toad, is a large, terrestrial true toad native to South and mainland Central America, but which has been introduced to various islands throughout Oceania and the Caribbean, as well as Northern Australia. It is a member of the genus Rhinella, which includes many true toad species found throughout Central and South America, but it was formerly assigned to the genus Bufo.
The Cane Toad is an old species. A fossil toad from the La Venta fauna of the late Miocene in Colombia is indistinguishable from modern cane toads from northern South America. It was discovered in a floodplain deposit, which suggests the R. marina habitat preferences have long been for open areas. The cane toad is a prolific breeder; females lay single-clump spawns with thousands of eggs. Its reproductive success is partly because of opportunistic feeding: it has a diet, unusual among anurans, of both dead and living matter. Adults average 4 to 6 inches in length; the largest recorded specimen had a snout-vent length of 9.4 inches.
The cane toad has poison glands, and the tadpoles are highly toxic to most animals if ingested. Its toxic skin can kill many animals, both wild and domesticated, and cane toads are particularly dangerous to dogs. Because of its voracious appetite, the cane toad has been introduced to many regions of the Pacific and the Caribbean islands as a method of agricultural pest control. The common name of the species is derived from its use against the cane beetle (Dermolepida albohirtum), which damages sugar cane. The cane toad is now considered a pest and an invasive species in many of its introduced regions. The 1988 film Cane Toads: An Unnatural History documented the trials and tribulations of the introduction of cane toads in Australia.
Description: Considered the largest species in the Bufonidae, the cane toad is very large; the females are significantly longer than males, reaching a typical length of 4 to 6 inches, with a maximum of 9.4 inches. Larger toads tend to be found in areas of lower population density. They have a life expectancy of 10 to 15 years in the wild, and can live considerably longer in captivity, with one specimen reportedly surviving for 35 years.
The skin of the cane toad is dry and warty. Distinct ridges above the eyes run down the snout. Individual cane toads can be grey, yellowish, red-brown, or olive-brown, with varying patterns. A large parotoid gland lies behind each eye. The ventral surface is cream-coloured and may have blotches in shades of black or brown. The pupils are horizontal and the irises golden. The toes have a fleshy webbing at their base, and the fingers are free of webbing.
Typically, juvenile cane toads have smooth, dark skin, although some specimens have a red wash. Juveniles lack the adults' large parotoid glands, so they are usually less poisonous. The tadpoles are small and uniformly black, and are bottom-dwellers, tending to form schools. Tadpoles range from 0.4 to 1.0 inches in length.
In the United States, the cane toad closely resembles many bufonid species. In particular, it could be confused with the Southern Toad (Bufo terrestris), which can be distinguished by the presence of two bulbs in front of the parotoid glands.
Habitat: The cane toad inhabits open grassland and woodland, and has displayed a "distinct preference" for areas modified by humans, such as gardens and drainage ditches. In their native habitats, the toads can be found in subtropical forests, although dense foliage tends to limit their dispersal.
Range: Attempts (both deliberate and accidental) have been made to introduce the species to the United States. These include introductions to Florida and to the islands of Hawaii, as well as largely unsuccessful introductions to Louisiana.
Initial releases into Florida failed. Attempted introductions before 1936 and 1944, intended to control sugarcane pests, were unsuccessful as the toads failed to proliferate. Later attempts failed in the same way. However, the toad gained a foothold in the state after an accidental release by an importer at Miami International Airport in 1957, and deliberate releases by animal dealers in 1963 and 1964 established the toad in other parts of Florida. Today, the cane toad is well established in the state, from the Keys to north of Tampa, and they are gradually extending further northward. In Florida, the toad is a regarded as a threat to native species and pets; so much so, the Florida Fish and Wildlife Conservation Commission recommends residents to kill them.
Diet: Most frogs identify prey by movement, and vision appears to be the primary method by which the cane toad detects prey; however, it can also locate food using its sense of smell. They eat a wide range of material; in addition to the normal prey of small rodents, other small mammals, reptiles, other amphibians, birds, and even bats and a range of invertebrates (such as ants, beetles, earwigs, dragonflies, grasshoppers, true bugs, crustaceans, and gastropods), they also eat plants, dog food, cat food, feces, and household refuse.
Reproduction: The cane toad begins life as an egg, which is laid as part of long strings of jelly in water. A female lays 8,000 to 25,000 eggs at once and the strings can stretch up to 66 ft in length. The black eggs are covered by a membrane and their diameter is about 0.067 to 0.079 inches. The rate at which an egg grows into a tadpole increases with temperature. Tadpoles typically hatch within 48 hours, but the period can vary from 14 hours to almost a week. This process usually involves thousands of tadpoles which are small, black, and have short tails forming into groups. Between 12 and 60 days are needed for the tadpoles to develop into juveniles, with four weeks being typical. Similarly to their adult counterparts, eggs and tadpoles are toxic to many animals.
Status: Globally it is a species of least concern. Here in the United States it is apparently secure.
Disclaimer: ITIS taxonomy is based on the latest scientific consensus available, and is provided as a general reference source for interested parties. However, it is not a legal authority for statutory or regulatory purposes. While every effort has been made to provide the most reliable and up-to-date information available, ultimate legal requirements with respect to species are contained in provisions of treaties to which the United States is a party, wildlife statutes, regulations, and any applicable notices that have been published in the Federal Register. For further information on U.S. legal requirements with respect to protected taxa, please contact the U.S. Fish and Wildlife Service.
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