Cane toad
   HOME

TheInfoList



OR:

The cane toad (''Rhinella marina''), also known as the giant neotropical toad or marine toad, is a large, terrestrial
true toad A true toad is any member of the family Bufonidae, in the order Anura (frogs and toads). This is the only family of anurans in which all members are known as toads, although some may be called frogs (such as harlequin frogs). The bufonids now ...
native to
South South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...
and mainland
Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
, but which has been introduced to various islands throughout
Oceania Oceania (, , ) is a geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern and Western hemispheres, Oceania is estimated to have a land area of and a population of around 44.5 million ...
and the
Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean ...
, as well as
Northern Australia The unofficial geographic term Northern Australia includes those parts of Queensland and Western Australia north of latitude 26° and all of the Northern Territory. Those local government areas of Western Australia and Queensland that lie p ...
. It is a member of the genus ''
Rhinella ''Rhinella'', commonly known as South American toads, beaked toads or Rio Viejo toads, is a genus of true toads native to Neotropical parts of Mexico, Central and South America. Additionally, the cane toad has been introduced to Australia, the Ca ...
'', which includes many true toad
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
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 (specimen UCMP 41159) from the La Venta fauna of the late
Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
in
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the ...
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 Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquati ...
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 in length; the largest recorded specimen had a snout-vent length of . The cane toad has poison
gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...
s, and the
tadpole A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found ...
s 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 Pest control is the regulation or management of a species defined as a pest; any animal, plant or fungus that impacts adversely on human activities or environment. The human response depends on the importance of the damage done and will range ...
. The common name of the species is derived from its use against the
cane beetle ''Dermolepida albohirtum'', the cane beetle, is a native Australian beetle and a parasite of sugarcane. Adult beetles eat the leaves of sugarcane, but greater damage is done by their larvae hatching underground and eating the roots, which eit ...
(''Dermolepida albohirtum''), which damages
sugar cane Sugarcane or sugar cane is a species of (often hybrid) tall, perennial grass (in the genus '' Saccharum'', tribe Andropogoneae) that is used for sugar production. The plants are 2–6 m (6–20 ft) tall with stout, jointed, fibrous stalk ...
. The cane toad is now considered a pest and an
invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...
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 The cane toad in Australia is regarded as an exemplary case of a " feral species", including rabbits, foxes, cats, and dogs, among others. Australia's relative isolation prior to European colonisation and the industrial revolution, both of w ...
.


Taxonomy

Historically, the cane toads were used to eradicate pests from
sugarcane Sugarcane or sugar cane is a species of (often hybrid) tall, perennial grass (in the genus '' Saccharum'', tribe Andropogoneae) that is used for sugar production. The plants are 2–6 m (6–20 ft) tall with stout, jointed, fibrous stalk ...
, giving rise to their common name. The cane toad has many other common names, including "giant toad" and "marine toad"; the former refers to its size, and the latter to the
binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bo ...
, ''R. marina''. It was one of many species described by
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, ...
in his 18th-century work ''
Systema Naturae ' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial ...
'' (1758). Linnaeus based the
specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bo ...
''marina'' on an illustration by Dutch zoologist 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
Trinidad Trinidad is the larger and more populous of the two major islands of Trinidad and Tobago. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is often referred to as the southernmos ...
ian English, they are commonly called ''crapaud'', the French word for toad. The genus ''Rhinella'' is considered to constitute a distinct
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of its own, thus changing the
scientific name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bo ...
of the cane toad. In this case, the specific name ''marinus'' (
masculine Masculinity (also called manhood or manliness) is a set of attributes, behaviors, and roles associated with men and boys. Masculinity can be theoretically understood as socially constructed, and there is also evidence that some behaviors ...
) changes to ''marina'' (feminine) to conform with the rules of gender agreement as set out by the
International Code of Zoological Nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the I ...
, changing the binomial name from ''Bufo marinus'' to ''Rhinella marina''; the binomial ''Rhinella marinus'' was subsequently introduced as a synonym through misspelling by Pramuk, Robertson, Sites, and Noonan (2008). Though controversial (with many traditional herpetologists still using ''Bufo marinus'') the binomial ''Rhinella marina'' is gaining in acceptance with such bodies as the
IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
, Encyclopaedia of Life, Amphibian Species of the World and increasing numbers of scientific publications adopting its usage. Since 2016, cane toad populations native to
Mesoamerica Mesoamerica is a historical region and cultural area in southern North America and most of Central America. It extends from approximately central Mexico through Belize, Guatemala, El Salvador, Honduras, Nicaragua, and northern Costa Rica. Wit ...
and northwestern South America are sometimes considered to be a separate species, '' Rhinella horribilis''. In Australia, the adults may be confused with large native frogs from the genera ''
Limnodynastes ''Limnodynastes'' (commonly known as the Australian swamp frogs) is a genus of frog native to Australia, southern New Guinea and some Torres Strait Islands. They are ground-dwelling frogs, with no toe pads. The size varies from 45 mm to 90 ...
'', ''
Cyclorana ''Ranoidea'' is a genus of frogs in the subfamily Pelodryadinae. They are found in Australia, New Guinea, and two nearby groups of islands: the Maluku Islands, and the Louisiade Archipelago. The circumscription of this taxon is still controve ...
'', and '' Mixophyes''. These species can be distinguished from the cane toad by the absence of large parotoid glands behind their eyes and the lack of a ridge between the nostril and the eye. Cane toads have been confused with the
giant burrowing frog The giant burrowing frog or eastern owl frog (''Heleioporus australiacus'') is a large frog species that occurs in coastal south-east New South Wales and Victoria in Australia. It is also known as the owl frog, southern owl frog, spotted owl f ...
(''Heleioporus australiacus''), because both are large and warty in appearance; however, the latter can be readily distinguished from the former by its vertical pupils and its silver-grey (as opposed to gold) irises. Juvenile cane toads may be confused with species of the genus '' Uperoleia'', but their adult colleagues can be distinguished by the lack of bright colouring on the groin and thighs. In the United States, the cane toad closely resembles many bufonid species. In particular, it could be confused with the
southern toad The southern toad (''Anaxyrus terrestris'') is a true toad native to the southeastern United States, from eastern Louisiana and southeastern Virginia south to Florida. It often lives in areas with sandy soils. It is nocturnal and spends the day i ...
(''Bufo terrestris''), which can be distinguished by the presence of two bulbs in front of the parotoid glands.


Genetics

The cane toad genome has been sequenced and certain Australian academics believe this will help in understanding how the toad can quickly evolve to adapt to new environments, the workings of its infamous toxin, and hopefully provide new options for halting this species' march across Australia and other places it has spread as an invasive pest.


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 , with a maximum of . 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
tadpole A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found ...
s are small and uniformly black, and are bottom-dwellers, tending to form
schools A school is an educational institution designed to provide learning spaces and learning environments for the teaching of students under the direction of teachers. Most countries have systems of formal education, which is sometimes compulsor ...
. Tadpoles range from in length.


Ecology, behaviour and life history

The common name "marine toad" and the scientific name ''Rhinella marina'' suggest a link to
marine life Marine life, sea life, or ocean life is the plants, animals and other organisms that live in the salt water of seas or oceans, or the brackish water of coastal estuaries. At a fundamental level, marine life affects the nature of the planet. ...
, but cane toads do not live in the sea. However, laboratory experiments suggest that tadpoles can tolerate salt concentrations equivalent to 15% of
seawater Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...
(~5.4‰), and recent field observations found living tadpoles and toadlets at salinities of 27.5‰ on
Coiba Island Coiba is the largest island in Central America, with an area of , off the Pacific coast of the Panamanian province of Chiriquí. It is part of the Tolé District of that province. History Coiba separated from continental Panama about 12,000 t ...
,
Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Co ...
. 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. The cane toad begins life as an egg, which is laid as part of long strings of jelly in water. A female lays 8,000–25,000 eggs at once and the strings can stretch up to in length. The black eggs are covered by a membrane and their diameter is about . 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. When they emerge, toadlets typically are about in length, and grow rapidly. While the rate of growth varies by region, time of year, and gender, an average initial growth rate of per day is seen, followed by an average rate of per day. Growth typically slows once the toads reach sexual maturity. This rapid growth is important for their survival; in the period between metamorphosis and subadulthood, the young toads lose the toxicity that protected them as eggs and tadpoles, but have yet to fully develop the parotoid glands that produce bufotoxin. Only an estimated 0.5% of cane toads reach adulthood, in part because they lack this key defense - but also due to tadpole cannibalism. Although cannibalism does occur in the native population in South America, the rapid evolution occurring in the unnaturally large population in Australia has produced tadpoles 30x more likely to be ''interested'' in cannibalising their siblings, and 2.6x more likely to actually ''do so''. They have also evolved to shorten their tadpole phase in response to the presence of older tadpoles. These changes are likely genetic, although no genetic basis has been determined. As with rates of growth, the point at which the toads become sexually mature varies across different regions. In New Guinea, sexual maturity is reached by female toads with a snout–vent length between , while toads in
Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Co ...
achieve maturity when they are between in length. In tropical regions, such as their native habitats, breeding occurs throughout the year, but in subtropical areas, breeding occurs only during warmer periods that coincide with the onset of the
wet season The wet season (sometimes called the Rainy season) is the time of year when most of a region's average annual rainfall occurs. It is the time of year where the majority of a country's or region's annual precipitation occurs. Generally, the sea ...
. The cane toad is estimated to have a critical thermal maximum of and a minimum of around . The ranges can change due to adaptation to the local environment. Cane toads from some populations can adjust their thermal tolerance within a few hours of encountering low temperatures. The toad is able to rapidly acclimate to the cold using physiological plasticity, though there is also evidence that more northerly populations of cane toads in the United States are better cold-adapted than more southerly populations. These adaptations have allowed the cane toad to establish invasive populations across the world. The toad’s ability to rapidly acclimate to thermal changes suggests that current models may underestimate the potential range of habitats that the toad can populate. The cane toad has a high tolerance to water loss; some can withstand a 52.6% loss of body water, allowing them to survive outside tropical environments.


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
rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...
s, other small
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...
s,
reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates ( lizards and snakes) and rhynchocephalia ...
s, other
amphibian Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbo ...
s,
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s, and even bats and a range of
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...
s (such as ants,
beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s,
earwig Earwigs make up the insect order Dermaptera. With about 2,000 species in 12 families, they are one of the smaller insect orders. Earwigs have characteristic cerci, a pair of forcep-like pincers on their abdomen, and membranous wings folde ...
s,
dragonflies A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonfly are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threa ...
,
grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshopp ...
s, true bugs,
crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...
s, and
gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
s), they also eat plants, dog food, cat food, feces, and household refuse.


Defences

The skin of the adult cane toad is toxic, as well as the enlarged parotoid glands behind the eyes, and other glands across its back. When the toad is threatened, its glands secrete a milky-white fluid known as bufotoxin. Components of bufotoxin are toxic to many animals; even human deaths have been recorded due to the consumption of cane toads. Dogs are especially prone to be poisoned by licking or biting toads. Pets showing excessive drooling, extremely red gums, head-shaking, crying, loss of coordination, and/or convulsions require immediate veterinary attention. Bufotenin, one of the chemicals excreted by the cane toad, is classified as a schedule 9 drug under Australian law, alongside
heroin Heroin, also known as diacetylmorphine and diamorphine among other names, is a potent opioid mainly used as a recreational drug for its euphoric effects. Medical grade diamorphine is used as a pure hydrochloride salt. Various white and bro ...
and LSD. The effects of bufotenin are thought to be similar to those of mild poisoning; the stimulation, which includes mild
hallucination A hallucination is a perception in the absence of an external stimulus that has the qualities of a real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. Hallucination is a combinati ...
s, lasts less than an hour. As the cane toad excretes bufotenin in small amounts, and other toxins in relatively large quantities, toad licking could result in serious illness or death. In addition to releasing toxin, the cane toad is capable of inflating its lungs, puffing up, and lifting its body off the ground to appear taller and larger to a potential predator. Since 2011, experimenters in the Kimberley region of Western Australia have used poisonous sausages containing toad meat in an attempt to protect native animals from cane toads' deadly impact. The Western Australian Department of Environment and Conservation, along with the University of Sydney, developed these sausage-shaped baits as a tool in order to train native animals not to eat the toads. By blending bits of toad with a nausea-inducing chemical, the baits train the animals to stay away from the amphibians.


Predators

Many species prey on the cane toad and its tadpoles in its native habitat, including the
broad-snouted caiman The broad-snouted caiman (''Caiman latirostris'') is a crocodilian in the family Alligatoridae found in eastern and central South America, including southeastern Brazil, northern Argentina, Uruguay, Paraguay, and Bolivia. It is found mostly in ...
(''Caiman latirostris''), the banded cat-eyed snake (''Leptodeira annulata''), eels (family Anguillidae), various species of
killifish A killifish is any of various oviparous (egg-laying) cyprinodontiform fish (including families Aplocheilidae, Cyprinodontidae, Fundulidae, Profundulidae and Valenciidae). All together, there are 1,270 species of killifish, the biggest family ...
, the rock flagtail ('' Kuhlia rupestris''), some species of
catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...
(order Siluriformes), some species of
ibis The ibises () (collective plural ibis; classical plurals ibides and ibes) are a group of long-legged wading birds in the family Threskiornithidae, that inhabit wetlands, forests and plains. "Ibis" derives from the Latin and Ancient Greek word ...
(subfamily Threskiornithinae), and ''
Paraponera clavata ''Paraponera clavata'' is a species of ant, commonly known as the bullet ant, named for its extremely painful sting. It inhabits humid lowland rainforests in Central and South America. Etymology The specific epithet of the ant, ', means "club- ...
'' (bullet ants). Predators outside the cane toad's native range include the whistling kite (''Haliastur sphenurus''), the rakali (''Hydromys chrysogaster''), the
black rat The black rat (''Rattus rattus''), also known as the roof rat, ship rat, or house rat, is a common long-tailed rodent of the stereotypical rat genus ''Rattus'', in the subfamily Murinae. It likely originated in the Indian subcontinent, but is ...
(''Rattus rattus'') and the water monitor (''Varanus salvator''). The tawny frogmouth (''Podargus strigoides'') and the Papuan frogmouth (''Podargus papuensis'') have been reported as feeding on cane toads; some Australian crows ('' Corvus'' spp.) have also learned strategies allowing them to feed on cane toads, such as using their beak to flip toads onto their backs. Opossums of the genus '' Didelphis'' likely can eat cane toads with impunity. Meat ants are unaffected by the cane toads' toxins, so are able to kill them. The cane toad's normal response to attack is to stand still and let its toxin kill the attacker, which allows the ants to attack and eat the toad. Saw-shelled turtles have also been seen successfully and safely eating cane toads.


Distribution

The cane toad is native to the Americas, and its range stretches from the
Rio Grande Valley The Lower Rio Grande Valley ( es, Valle del Río Grande), commonly known as the Rio Grande Valley or locally as the Valley or RGV, is a region spanning the border of Texas and Mexico located in a floodplain of the Rio Grande near its mouth. ...
in
South Texas South Texas is a region of the U.S. state of Texas that lies roughly south of—and includes—San Antonio. The southern and western boundary is the Rio Grande, and to the east it is the Gulf of Mexico. The population of this region is about 4.96 ...
to the central
Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...
and southeastern
Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...
, and some of the continental islands near
Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
(such as
Trinidad Trinidad is the larger and more populous of the two major islands of Trinidad and Tobago. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is often referred to as the southernmos ...
and
Tobago Tobago () is an island and ward within the Republic of Trinidad and Tobago. It is located northeast of the larger island of Trinidad and about off the northeastern coast of Venezuela. It also lies to the southeast of Grenada. The offic ...
). This area encompasses both
tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...
and
semiarid A semi-arid climate, semi-desert climate, or steppe climate is a dry climate sub-type. It is located on regions that receive precipitation below potential evapotranspiration, but not as low as a desert climate. There are different kinds of semi- ...
environments. The density of the cane toad is significantly lower within its native distribution than in places where it has been introduced. In South America, the density was recorded to be 20 adults per 100 m (109 yd) of shoreline, 1 to 2% of the density in Australia.


As an introduced species

The cane toad has been introduced to many regions of the world—particularly the Pacific—for the biological control of agricultural pests. These introductions have generally been well documented, and the cane toad may be one of the most studied of any
introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there ...
. Before the early 1840s, the cane toad had been introduced into
Martinique Martinique ( , ; gcf, label= Martinican Creole, Matinik or ; Kalinago: or ) is an island and an overseas department/region and single territorial collectivity of France. An integral part of the French Republic, Martinique is located in ...
and
Barbados Barbados is an island country in the Lesser Antilles of the West Indies, in the Caribbean region of the Americas, and the most easterly of the Caribbean Islands. It occupies an area of and has a population of about 287,000 (2019 estima ...
, from
French Guiana French Guiana ( or ; french: link=no, Guyane ; gcr, label= French Guianese Creole, Lagwiyann ) is an overseas department/region and single territorial collectivity of France on the northern Atlantic coast of South America in the Guianas ...
and
Guyana Guyana ( or ), officially the Cooperative Republic of Guyana, is a country on the northern mainland of South America. Guyana is an indigenous word which means "Land of Many Waters". The capital city is Georgetown. Guyana is bordered by the ...
. An introduction to
Jamaica Jamaica (; ) is an island country situated in the Caribbean Sea. Spanning in area, it is the third-largest island of the Greater Antilles and the Caribbean (after Cuba and Hispaniola). Jamaica lies about south of Cuba, and west of Hispa ...
was made in 1844 in an attempt to reduce the rat population. Despite its failure to control the rodents, the cane toad was introduced to
Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...
in the early 20th century in the hope that it would counter a beetle infestation ravaging the sugarcane plantations. The Puerto Rican scheme was successful and halted the economic damage caused by the beetles, prompting scientists in the 1930s to promote it as an ideal solution to agricultural pests. As a result, many countries in the Pacific region emulated the lead of Puerto Rico and introduced the toad in the 1930s. Introduced populations are in
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
,
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...
,
Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...
, the
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...
, the Ogasawara,
Ishigaki Island , also known as ''Ishigakijima'', is a Japanese island south-west of Okinawa Hontō and the second-largest island of the Yaeyama Island group, behind Iriomote Island. It is located approximately south-west of Okinawa Hontō. It is within the ...
and the
Daitō Islands The are an archipelago consisting of three isolated coral islands in the Philippine Sea southeast of Okinawa. The islands have a total area of and a population of 2,107. Administratively, the whole group belongs to Shimajiri District of Oki ...
of Japan, ,
Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the no ...
Nantou
Caotun Caotun Township, formerly transliterated as Tsaotun Township, is an urban township in the northwest of Nantou County, Taiwan. It is the largest township in Taiwan by population. History The area was historically known as ''Chháu-ê-tun'' () w ...
, most Caribbean islands,
Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consis ...
and many other Pacific islands, including
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...
. Since then, the cane toad has become a pest in many host countries, and poses a serious threat to native animals.


Australia

Following the apparent success of the cane toad in eating the beetles threatening the sugarcane plantations of Puerto Rico, and the fruitful introductions into Hawaii and the Philippines, a strong push was made for the cane toad to be released in Australia to negate the pests ravaging the Queensland cane fields. As a result, 102 toads were collected from Hawaii and brought to Australia. Queensland's sugar scientists released the toad into cane fields in August 1935. After this initial release, the Commonwealth Department of Health decided to ban future introductions until a study was conducted into the feeding habits of the toad. The study was completed in 1936 and the ban lifted, when large-scale releases were undertaken; by March 1937, 62,000 toadlets had been released into the wild. The toads became firmly established in Queensland, increasing exponentially in number and extending their range into the
Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an Australian territory in the central and central northern regions of Australia. The Northern Territory shares its borders with Western Aust ...
and
New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...
. In 2010, one was found on the far western coast in
Broome, Western Australia Broome, also known as Rubibi by the Yawuru people, is a coastal pearling and tourist town in the Kimberley region of Western Australia, north of Perth. In the the population was recorded as 14,660. It is the largest town in the Kimberley re ...
. However, the toad was generally unsuccessful in reducing the targeted grey-backed cane beetles (''
Dermolepida albohirtum ''Dermolepida albohirtum'', the cane beetle, is a native Australian beetle and a parasite of sugarcane. Adult beetles eat the leaves of sugarcane, but greater damage is done by their larvae hatching underground and eating the roots, which eit ...
''), in part because the cane fields provided insufficient shelter for the predators during the day, and in part because the beetles live at the tops of sugar cane—and cane toads are not good climbers. Since its original introduction, the cane toad has had a particularly marked effect on Australian
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity'') ...
. The population of a number of native predatory reptiles has declined, such as the
varanid The Varanidae are a family of lizards in the superfamily Varanoidea within the Anguimorpha group. The family, a group of carnivorous and frugivorous lizards, includes the living genus '' Varanus'' and a number of extinct genera more closely rela ...
lizards ''
Varanus mertensi Mertens' water monitor (''Varanus mertensi''), also called commonly Mertens's water monitor, and often misspelled Mertin's water monitor, is a species of lizard in the family Varanidae. The species is endemic to northern Australia, and is a wid ...
'', '' V. mitchelli'', and '' V. panoptes'', the land snakes '' Pseudechis australis'' and '' Acanthophis antarcticus'', and the crocodile species ''
Crocodylus johnstoni The freshwater crocodile (''Crocodylus johnstoni''), also known as the Australian freshwater crocodile, Johnstone's crocodile or the freshie, is a species of crocodile endemic to the northern regions of Australia. Unlike their much larger Aust ...
''; in contrast, the population of the
agamid Agamidae is a family of over 300 species of iguanian lizards indigenous to Africa, Asia, Australia, and a few in Southern Europe. Many species are commonly called dragons or dragon lizards. Overview Phylogenetically, they may be sister to the ...
lizard '' Amphibolurus gilberti''—known to be a prey item of ''V. panoptes''—has increased.. On snake populations see . Meat ants, however, are able to kill cane toads.''Meat Ant.''
Australian Environmental Pest Managers Association (AEPMA) (accessed July 2022)


Caribbean

The cane toad was introduced to various Caribbean islands to counter a number of pests infesting local crops. While it was able to establish itself on some islands, such as
Barbados Barbados is an island country in the Lesser Antilles of the West Indies, in the Caribbean region of the Americas, and the most easterly of the Caribbean Islands. It occupies an area of and has a population of about 287,000 (2019 estima ...
,
Jamaica Jamaica (; ) is an island country situated in the Caribbean Sea. Spanning in area, it is the third-largest island of the Greater Antilles and the Caribbean (after Cuba and Hispaniola). Jamaica lies about south of Cuba, and west of Hispa ...
, and
Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...
, other introductions, such as in
Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribb ...
before 1900 and in 1946, and on the islands of
Dominica Dominica ( or ; Kalinago: ; french: Dominique; Dominican Creole French: ), officially the Commonwealth of Dominica, is an island country in the Caribbean. The capital, Roseau, is located on the western side of the island. It is geographical ...
and
Grand Cayman Grand Cayman is the largest of the three Cayman Islands and the location of the territory's capital, George Town. In relation to the other two Cayman Islands, it is approximately 75 miles (121 km) southwest of Little Cayman and 90 miles (1 ...
, were unsuccessful. The earliest recorded introductions were to Barbados and
Martinique Martinique ( , ; gcf, label= Martinican Creole, Matinik or ; Kalinago: or ) is an island and an overseas department/region and single territorial collectivity of France. An integral part of the French Republic, Martinique is located in ...
. The Barbados introductions were focused on the biological control of pests damaging the sugarcane crops, and while the toads became abundant, they have done even less to control the pests than in Australia.Kennedy, Anthony quoted in The toad was introduced to Martinique from
French Guiana French Guiana ( or ; french: link=no, Guyane ; gcr, label= French Guianese Creole, Lagwiyann ) is an overseas department/region and single territorial collectivity of France on the northern Atlantic coast of South America in the Guianas ...
before 1944 and became established. Today, they reduce the
mosquito Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "li ...
and mole cricket populations. A third introduction to the region occurred in 1884, when toads appeared in Jamaica, reportedly imported from Barbados to help control the rodent population. While they had no significant effect on the rats, they nevertheless became well established. Other introductions include the release on
Antigua Antigua ( ), also known as Waladli or Wadadli by the native population, is an island in the Lesser Antilles. It is one of the Leeward Islands in the Caribbean region and the main island of the country of Antigua and Barbuda. Antigua and Bar ...
—possibly before 1916, although this initial population may have died out by 1934 and been reintroduced at a later date— and
Montserrat Montserrat ( ) is a British Overseas Territory in the Caribbean. It is part of the Leeward Islands, the northern portion of the Lesser Antilles chain of the West Indies. Montserrat is about long and wide, with roughly of coastline. It is n ...
, which had an introduction before 1879 that led to the establishment of a solid population, which was apparently sufficient to survive the Soufrière Hills volcano eruption in 1995. In 1920, the cane toad was introduced into Puerto Rico to control the populations of white grub (''Phyllophaga'' spp.), a sugarcane pest. Before this, the pests were manually collected by humans, so the introduction of the toad eliminated labor costs. A second group of toads was imported in 1923, and by 1932, the cane toad was well established.. "After a completely successful method of killing white grubs by chemical means was found, the only opportunities for its use in Puerto Rico have been limited to small areas in pineapple plantations at elevations where the toad is even yet not present in sufficient abundance." The population of white grubs dramatically decreased, and this was attributed to the cane toad at the annual meeting of the International Sugar Cane Technologists in Puerto Rico. However, there may have been other factors. The six-year period after 1931—when the cane toad was most prolific, and the white grub had a dramatic decline—had the highest-ever rainfall for Puerto Rico. Nevertheless, the cane toad was assumed to have controlled the white grub; this view was reinforced by a ''
Nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...
'' article titled "Toads save sugar crop", and this led to large-scale introductions throughout many parts of the Pacific. The cane toad has been spotted in Carriacou and
Dominica Dominica ( or ; Kalinago: ; french: Dominique; Dominican Creole French: ), officially the Commonwealth of Dominica, is an island country in the Caribbean. The capital, Roseau, is located on the western side of the island. It is geographical ...
, the latter appearance occurring in spite of the failure of the earlier introductions. On September 8, 2013, the cane toad was also discovered on the island of
New Providence New Providence is the most populous island in the Bahamas, containing more than 70% of the total population. It is the location of the national capital city of Nassau, whose boundaries are coincident with the island; it had a population of 246 ...
in the Bahamas.


The Philippines

The cane toad was first introduced deliberately into the
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...
in 1930 as a biological control agent of pests in sugarcane plantations, after the success of the experimental introductions into Puerto Rico. It subsequently became the most ubiquitous amphibian in the islands. It still retains the common name of ''bakî'' or ''kamprag'' in the
Visayan languages The Bisayan languages or Visayan languages are a subgroup of the Austronesian languages spoken in the Philippines. They are most closely related to Tagalog and the Bikol languages, all of which are part of the Central Philippine languages. M ...
, a
corruption Corruption is a form of dishonesty or a criminal offense which is undertaken by a person or an organization which is entrusted in a position of authority, in order to acquire illicit benefits or abuse power for one's personal gain. Corruption m ...
of 'American frog', referring to its origins. It is also commonly known as "bullfrog" in Philippine English.


Fiji

The cane toad was introduced into
Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consis ...
to combat insects that infested sugarcane plantations. The introduction of the cane toad to the region was first suggested in 1933, following the successes in Puerto Rico and Hawaii. After considering the possible side effects, the national government of Fiji decided to release the toad in 1953, and 67 specimens were subsequently imported from Hawaii. Once the toads were established, a 1963 study concluded, as the toad's diet included both harmful and beneficial invertebrates, it was considered "economically neutral". Today, the cane toad can be found on all major islands in Fiji, although they tend to be smaller than their counterparts in other regions.


New Guinea

The cane toad was introduced into
New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torres ...
to control the hawk moth larvae eating
sweet potato The sweet potato or sweetpotato ('' Ipomoea batatas'') is a dicotyledonous plant that belongs to the bindweed or morning glory family, Convolvulaceae. Its large, starchy, sweet-tasting tuberous roots are used as a root vegetable. The young ...
crops. The first release occurred in 1937 using toads imported from Hawaii, with a second release the same year using specimens from the Australian mainland. Evidence suggests a third release in 1938, consisting of toads being used for human pregnancy tests—many species of toad were found to be effective for this task, and were employed for about 20 years after the discovery was announced in 1948. Initial reports argued the toads were effective in reducing the levels of
cutworm Cutworms are moth larvae that hide under litter or soil during the day, coming out in the dark to feed on plants. A larva typically attacks the first part of the plant it encounters, namely the stem, often of a seedling, and consequently cuts it ...
s and sweet potato yields were thought to be improving. As a result, these first releases were followed by further distributions across much of the region, although their effectiveness on other crops, such as cabbages, has been questioned; when the toads were released at Wau, the cabbages provided insufficient shelter and the toads rapidly left the immediate area for the superior shelter offered by the forest. A similar situation had previously arisen in the Australian cane fields, but this experience was either unknown or ignored in New Guinea. The cane toad has since become abundant in rural and urban areas.


United States

The cane toad naturally exists in
South Texas South Texas is a region of the U.S. state of Texas that lies roughly south of—and includes—San Antonio. The southern and western boundary is the Rio Grande, and to the east it is the Gulf of Mexico. The population of this region is about 4.96 ...
, but attempts (both deliberate and accidental) have been made to introduce the species to other parts of the country. These include introductions to
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...
and to the islands of Hawaii, as well as largely unsuccessful introductions to
Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is bord ...
. 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 Miami International Airport , also known as MIA and historically as Wilcox Field, is the primary airport serving the greater Miami metropolitan area with over 1,000 daily flights to 167 domestic and international destinations, including most c ...
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 Key or The Key may refer to: Common meanings * Key (cryptography), a piece of information that controls the operation of a cryptography algorithm * Key (lock), device used to control access to places or facilities restricted by a lock * Key (m ...
to north of
Tampa Tampa () is a city on the Gulf Coast of the U.S. state of Florida. The city's borders include the north shore of Tampa Bay and the east shore of Old Tampa Bay. Tampa is the largest city in the Tampa Bay area and the seat of Hillsborough C ...
, 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 The Florida Fish and Wildlife Conservation Commission (FWC) is a Florida government agency founded in 1999 and headquartered in Tallahassee. It manages and regulates the state's fish and wildlife resources, and enforces related laws. Officers ar ...
recommends residents to kill them. Around 150 cane toads were introduced to
Oahu Oahu () ( Hawaiian: ''Oʻahu'' ()), also known as "The Gathering Place", is the third-largest of the Hawaiian Islands. It is home to roughly one million people—over two-thirds of the population of the U.S. state of Hawaii. The island of O ...
in Hawaii in 1932, and the population swelled to 105,517 after 17 months. The toads were sent to the other islands, and more than 100,000 toads were distributed by July 1934; eventually over 600,000 were transported.


Uses

Other than the use as a biological control for pests, the cane toad has been employed in a number of commercial and noncommercial applications. Traditionally, within the toad's natural range in South America, the Embera-Wounaan would "milk" the toads for their toxin, which was then employed as an
arrow poison Arrow poisons are used to poison arrow heads or darts for the purposes of hunting and warfare. They have been used by indigenous peoples worldwide and are still in use in areas of South America, Africa and Asia. Notable examples are the poisons se ...
. The toxins may have been used as an
entheogen Entheogens are psychoactive substances that induce alterations in perception, mood, consciousness, cognition, or behavior for the purposes of engendering spiritual development or otherwiseRätsch, Christian, ''The Encyclopedia of Psychoac ...
by the
Olmec The Olmecs () were the earliest known major Mesoamerican civilization. Following a progressive development in Soconusco, they occupied the tropical lowlands of the modern-day Mexican states of Veracruz and Tabasco. It has been speculated that ...
people. The toad has been hunted as a food source in parts of
Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...
, and eaten after the careful removal of the skin and parotoid glands. When properly prepared, the meat of the toad is considered healthy and as a source of
omega-3 fatty acid Omega−3 fatty acids, also called Omega-3 oils, ω−3 fatty acids or ''n''−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond, three atoms away from the terminal methyl group in their chem ...
s. More recently, the toad's toxins have been used in a number of new ways: bufotenin has been used in Japan as an
aphrodisiac An aphrodisiac is a substance that increases sexual desire, sexual attraction, sexual pleasure, or sexual behavior. Substances range from a variety of plants, spices, foods, and synthetic chemicals. Natural aphrodisiacs like cannabis or cocai ...
and a hair restorer, and in
cardiac surgery Cardiac surgery, or cardiovascular surgery, is surgery on the heart or great vessels performed by cardiac surgeons. It is often used to treat complications of ischemic heart disease (for example, with coronary artery bypass grafting); to co ...
in China to lower the heart rates of patients. New research has suggested that the cane toad's poison may have some applications in treating
prostate cancer Prostate cancer is cancer of the prostate. Prostate cancer is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that su ...
. Other modern applications of the cane toad include pregnancy testing, as pets, laboratory research, and the production of
leather Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hog ...
goods. Pregnancy testing was conducted in the mid-20th century by injecting urine from a woman into a male toad's lymph sacs, and if
spermatozoa A spermatozoon (; also spelled spermatozoön; ; ) is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote. (A zygote is a single cell, with a complete set of chromos ...
appeared in the toad's urine, the patient was deemed to be pregnant. The tests using toads were faster than those employing mammals; the toads were easier to raise, and, although the initial 1948 discovery employed ''
Bufo arenarum ''Rhinella arenarum'' is a species of toad in the family Bufonidae that is found in southern Brazil and Uruguay; can also occur in Paraguay. It is also found in Argentina from the Chubut Province northward, Bolivia , image_flag ...
'' for the tests, it soon became clear that a variety of anuran species were suitable, including the cane toad. As a result, toads were employed in this task for around 20 years. As a laboratory animal, the cane toad has numerous advantages: they are plentiful, and easy and inexpensive to maintain and handle. The use of the cane toad in experiments started in the 1950s, and by the end of the 1960s, large numbers were being collected and exported to high schools and universities. Since then, a number of Australian states have introduced or tightened importation regulations. There are several commercial uses for dead cane toads. Cane toad skin is made into leather and novelty items. Stuffed cane toads, posed and accessorised, are merchandised at souvenir shops for tourists. Attempts have been made to produce fertiliser from toad carcasses.


Invasive species

Cane toads pose a serious threat to native species when introduced to a new ecosystem. Classified as an invasive species in over 20 countries, multiple reports exist of the cane toad moving into a new area to be followed by a decline in the biodiversity in that region. The most documented region of the cane toad's invasion and subsequent effect on native species is
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
, where multiple surveys and observations of the toad's conquest have been completed. The best way to illustrate this effect is through the plight of the northern quoll, as well as Mertens' water monitor, a large lizard native to South and Southeast Asia. Two sites were chosen to study the effects of cane toads on the northern quoll, one of which was at Mary River ranger station, which is located in the southern region of
Kakadu National Park Kakadu National Park is a protected area in the Northern Territory of Australia, southeast of Darwin. It is a World Heritage Site. Kakadu is also gazetted as a locality, covering the same area as the national park, with 313 people recorded liv ...
. The other site was located at the north end of the park. In addition to these two sites, a third site was located at the East Alligator ranger station, and this site was used as a control site, where the cane toads would not interact with the northern quoll population. Monitoring of the quoll population began at the Mary River ranger station using radio tracking in 2002, months before the first cane toads arrived at the site. After the arrival of the cane toads, the population of northern quolls in the Mary River site plummeted between October and December 2002, and by March 2003, the northern quoll appeared to be extinct in this section of the park, as no northern quolls were caught in the trapping trips in the following two months. In contrast, the population of northern quolls in the control site at the East Alligator ranger station remained relatively constant, not showing any symptoms of declining. The evidence from the Kakadu National Park is compelling not only because of the timing of the population of northern quolls plummeting just months after the arrival of the cane toad, but also because in the Mary River region 31% of mortalities within the quoll population were attributed to lethal toxic ingestion, as no signs of disease, parasite infestation, or any other obvious changes at the site were found that could have caused such a rapid decline. The most obvious evidence that supports the hypothesis that the invasion of the cane toads caused the
local extinction Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...
of the northern quoll is that the closely monitored population of the control group, in the absence of cane toads, showed no signs of decline. In the case of Mertens' water monitor, only one region was monitored, but over the course of 18 months. This region is located 70 km south of Darwin, at the Manton Dam Recreation Area. Within the Manton Dam Recreation Area, 14 sites were set up to survey the population of water monitors, measuring abundance and site occupancy at each one. Seven surveys were conducted, each of which ran for 4 weeks and included 16 site visits, where each site was sampled twice per day for 2 consecutive days throughout the 4 weeks. Each site visit occurred between 7:30 and 10:30 am, and 4:00–7:00 pm, when ''Varanus mertensi'' can be viewed sunbathing on the shore or wrapped around a tree branch close to shore. The whole project lasted from December 2004 to May 2006, and had a total of 194 sightings of ''Varanus mertensi'' in 1568 site visits. Of the seven surveys, abundance was highest during the second survey, which took place in February 2005, 2 months into the project. Following this measurement, the abundance declined in the next four surveys, before declining sharply after the second to last survey in February 2006. In the final survey taken in May 2006, only two ''V. mertensi'' lizards were observed. Cane toads were first recorded in the region of study during the second survey during February 2005, also when the water monitor abundance was at its highest over the course of the study. Numbers of the cane toad population stayed low for the next year after introduction, and then skyrocketed to its peak in the last survey during May 2006. When compared, the two populations side by side clearly show that the onset of the cane toads had an immediate negative impact on the monitors, as their population began to drop in February 2005, which was when the first cane toads entered the Manton Dam Recreation Area. At the end of the study, some scattered populations of water monitors remained in the upper sites of the Manton Dam, which suggests that local extinctions occurred at certain shoreline sites within Manton Dam, but a complete extinction of the population did not occur.


References

Notes Bibliography * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *


External links


Species Profile – Cane Toad (''Rhinella marina'')
National Invasive Species Information Center,
United States National Agricultural Library The United States National Agricultural Library (NAL) is one of the world's largest agricultural research libraries, and serves as a national library of the United States and as the library of the United States Department of Agriculture. Located ...
. Lists general information and resources for cane toad. {{Taxonbar , from=Q321087 Rhinella Amphibians described in 1758 Taxa named by Carl Linnaeus Agricultural pests Amphibians of South America Amphibians of Central America Fauna of the Rio Grande valleys Vertebrates of Brazil Vertebrates of Guyana Amphibians of Trinidad and Tobago Amphibians of the Dominican Republic Fauna of Barbados Amphibians of Queensland Amphibians of New South Wales Amphibians of the Northern Territory Amphibians of Japan Frogs of Australia Amphibians of Mauritius