Cane Toad

Description:

The cane toad is the largest species in the family Bufonidae. Adult cane toads are usually heavy-built and weigh an average of up to 1.8 kg. (4 lbs.). Their size may vary from 15–23 cm.(4-9 in.) and their skin is warty. The coloration on their back and sides may vary from olive-brown or reddish-brown, gray, and yellow while their bellies are semi-yellow or semi-white with darker mottling. Their body is round and flat, has prominent corneal crests, and light middorsal stripes. Their front feet are unwebbed, but their back feet have tough, leathery webbing. Cane toads have short legs and a ridged bony head that extends forward from their eyes to their nose. Behind their ears lie the parotid glands, which usually causes their head to appear swollen. These glands are used for defense against predators. The parotid gland produces milky toxic secretion or poison that is dangerous to many species. This venom primarily affects the functioning of the heart. Envenomation is painful, but is usually not fatal for humans. However, it does have some effects, such as burning of the eyes and hands, and skin irritation.

Habitat:

Native to Central and South America, Cane toads were introduced to Australia from Hawaii in June 1935 by the Bureau of Sugar Experiment Stations in an attempt to control the native cane beetle (Dermolepida albohirtum). These beetles are native to Australia and they are detrimental to sugar cane crops, which are a major source of income for Australia. Adult cane beetles eat the crop's leaves, but the main problem is the larvae, who feed on the roots. Adult cane beetles have a heavy exoskeleton and their eggs and larva are often buried underground, making them difficult to exterminate. Furthermore, conventional methods of pest control, such as pesticide use, would eradicate harmless species of insects as well, making it an unsatisfactory method. The cane toads bred immediately in captivity, and by August 1935 more than 102 young toads were released in areas around Cairns, Gordonvale and Innisfail in northern Queensland. More toads were released around Ingham, Ayr, Mackay and Bundaberg. Releases were temporarily limited because of environmental concerns but resumed in other areas after September 1936. Since their release, toads have rapidly multiplied in population and now number over 200 million and have been known to spread diseases affecting local biodiversity. Unfortunately, the introduction of the toads has not only caused large environmental detriment, but there is also no evidence that they have had an impact on the cane beetles they were introduced to predate. The toads have steadily expanded their range through Queensland, reaching the border with New South Wales in 1978 and the Northern Territory in 1984. The toads on the western frontier of their advance have evolved larger legs; this is thought to be related to their ability to travel farther. As a consequence of their longer legs, larger bodies, and faster movement, about 10% of the leading edge cane toads have also developed arthritis. It is estimated that cane toads migrate at an average of 40 kilometres (25 mi) per year currently.