Cane toad

The cane toad (Bufo marinus), also known as the Giant Neotropical Toad or Marine Toad, is a large, terrestrial true toad native to Central and South America. It is a member of the subgenus Chaunus of the genus Bufo, which includes many different true toad species throughout Central and South America. The cane toad is a prolific breeder; females lay single-clump spawns with large numbers 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 10 to 15 centimetres (4–6 in) in length; the largest recorded specimen weighed 2.65 kg (5.8 lb) with a length of 38 cm (15 in) from snout to vent.

The cane toad has poison glands, and the tadpoles are highly toxic to most animals if ingested. 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, notably failing in the case of Australia in 1935, and derives its common name from its use against the greyback cane beetle pests. The cane toad is now considered a pest and invasive species in many of its introduced regions, because its toxic skin kills many native predators when ingested. It has many negative effects on farmers because of pets and animals eating the creatures.

Taxonomy

The common name of "cane toad" is derived from the original purpose of using it to eradicate pests in sugar cane crops. The cane toad has many other common names, including "Giant Toad" and "Marine Toad"; the former refers to their size, and the latter to the binomial name, Bufo marinus. It was one of the many species originally described by Linnaeus in his 18th century work Systema Naturae. Linnaeus based the specific epithet, marinus, on an illustration by Albertus Seba, who mistakenly believed the cane toad to inhabit both terrestrial and marine environments. Other common names include "Giant Neotropical Toad," "Dominican Toad," "Giant Marine Toad," and "South American Cane Toad." In Trinidadian English they are commonly called "Crapaud" (the French name for "toad").

In Australia, the adults may be confused with species of the Limnodynastes, Neobatrachus, Mixophyes, and Notaden genera. These species can be readily distinguished from the cane toad by the lack of large parotoid glands behind their eyes. Cane toads have been confused with the Giant Burrowing Frog (Heleioporus australiacus), because both are large and warty in appearance; however, the Giant Burrowing Frog can be readily distinguished from the cane toad by its vertical pupils. Juvenile cane toads may be confused with species of the Uperoleia genus, because they all have large parotoid glands; juvenile cane toads can be distinguished from these species by the ridging around their eyes and the lack of bright colouring on their thighs.
Lightly coloured cane toad

In the United States, the cane toad closely resembles many Bufonid species. In particular, it could be confused with the Southern toad (Bufo terrestris) and Fowler's Toad (Bufo fowleri). The Southern Toad can be distinguished by the presence of two bulbs in front of the parotoid glands, and the Fowler's Toad has a pale, cream-white stripe that runs down the dorsal surface; the cane toad lacks this stripe.

It is possible to confuse the cane toad with the Rococo Toad (Bufo schneideri), sometimes referred to as Schneider's Toad, whose range overlaps that of the cane toad. The Rococo Toad grows to nearly the same size but has additional poison glands on its back legs which can be used to reliably identify it. Within its native range, the cane toad can be distinguished from the other true toads by the shape of its parotoid glands and the arrangement of the ridges on its head.

Description

The cane toad is very large; the females are larger than males, reaching an average length of 10–15 centimetres (4–6 in), and much longer in some cases. "Prinsen", a toad kept as a pet in Sweden, is listed by the Guinness Book of Records as the largest recorded specimen. It reportedly weighed 2.65 kilograms (5.84 lb) and measured 38 centimetres (15 in) from snout to vent, or 54 centimetres (21 in) when fully extended. (3 lb). They have a life expectancy of 10 to 15 years in the wild and as long as 20 years in captivity.

The skin of the cane toad is dry and warty. It has distinct ridges above the eyes which run down the snout. Cane toads can be grey, brown, red-brown or olive in colour, with varying patterns. A large parotoid gland lies behind each eye. The ventral surface is cream 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.

Juvenile cane toads are much smaller than adult cane toads—only 5 to 10 centimetres (2–4 in) long. Typically, they have smooth, dark skin, although some specimens have a red wash. Juveniles lack the adults' large parotoid glands, so they are usually less poisonous. Because they lack this key defence, it is estimated that only 0.5% of metamorph Cane toads reach adulthood. The tadpoles are small and uniformly black. They are bottom-dwellers and congregate around plants forming schools. Tadpoles reach 27 millimetres (1 in) in length but are smaller—up to 22 millimetres (0.9 in)—under overcrowded conditions.