Cane toad is a true toad belonging to the genus Rhinella. In the past, it was a member of the genus Bufo that included many true toad species commonly found in Central and Southern America. Cane toad is the largest toad species in the world. Once, this species of toad was used to get rid of the pests and insects (e.g. greybacked cane beetle) that threatened the sugarcane fields; and that’s how it got its present-day common name. Rhinella marina is considered to be a very old species. A La Venta fauna fossil specimen (UCMP 41159) is identical to that of the modern cane toads in South America.
Cane toads face no threat with regards to population decrease. This species is considered as pests at all the regions where they have been introduced in the past. In the IUCN Red List of Threatened Species, Rhinella marina falls into ‘Least Concern’ category.
Species: R. marina
The scientific name for cane toad is Rhinella marina.
The length of an adult cane toad revolves around 10 to 15 centimeters. Each specimen weighs around 80 to 120 grams. Females tend to be quite long compared to males.
It has been noted that the size of cane toads are larger in places where its population density is low. The skin color of cane toads varies in individuals ranging from olive-brown to red-brown, grey, and yellowish grey with different patterns. Its skin is warty and dry. It has an elongated strip that starts above their eyes and goes all the way down to the snout. This species has parotoid glands behind their eyes. Their ventral region is primarily cream-coloured; and may carry brown or black patches. Its toes are webbed at the base, but the fingers are not webbed.
Cane toad is a tropical species that inhabit forested areas, woodlands, open grasslands with semi-permanent, or permanent water nearby. People have observed that in some places, especially where they have been introduced, cane toads prefer to live in places modified by humans, such as drainage canals, gardens etc.
Cane toad’s native range includes Texas’ Rio Grande Valley; south to Central Amazon region, extending to south-eastern Peru. Rhinella marina population had been introduced to South Florida (Hillsborough, Tampa Bay, Key West etc.), Hawaiian islands, Caribbean Islands, and many parts of Australia.
Unlike most frog species, which identify its prey by movement, cane toads primarily detect its prey by vision. They also use their sense of smell to find food. In the dry, and cold seasons, they stay idle in shallow cavity underneath the ground.
Cane toad’s skin, parotoid glands, and other glands carry poison. When they feel threatened, they release a whitish toxic fluid called bufotoxin made up of cardio-active substances; and it is poisonous to animals, and even humans. The power of the toxin changes throughout their lifetime. Apart from releasing toxins, their defensive behavior includes inflating its lungs, lifting its body on its legs while puffing up to appear threatening to potential predators.
In tropical areas, breeding season last throughout the year, while in the subtropical regions, breeding takes place during warmer spells which concur with the start of a wet season.
Males assemble near slow-moving, or still water-bodies, and start mating calls. Each female can lay 8000 to 30000 eggs in the form of a jelly-like string. However, only 0.5% reach adulthood on average. Successful males can fertilize the eggs of many females, and it has also been noted that a single female’s eggs can be fertilized by more than one male. Eggs hatch within 2-7 days. Tadpoles tend to be small – approximately 10–11 mm in length, black in color, with a short tail. They develop into juveniles in 12 to 62 days. Their growth rate varies depending on the region, temperature and gender. Like an adult cane toad, both eggs and tadpoles are also toxic to animals.
Cane toad’s diet is quite atypical among anurans. They feed on both living and dead matter. It has been observed that they generally hunt around for food at night. They feed on reptiles, small rodents, beetles, ants, amphibians, birds as well as a wide range of invertebrates. They have also been seen eating plant matter, household refuse, cat and dog foods among others.
Cane toad’s lifespan is 10 to 15 years in its native, natural environment. However, it lives longer in captivity; and, one such specimen had lived for 35 years.
Invasive Species Specialist Group lists Cane toad as one of the top hundred worst invasive species in the world.
Cane toad’s poison has adverse effects on humans. If the toxin is swallowed, it may affect blood pressure, heart rate; and may also lead to vomiting, twitching, to paralysis.
The Embera–Wounaan, a semi-nomadic aboriginal people in Panama, uses Cane toad toxin as arrow poison.
In some parts of Peru, cane toad has been hunted as food (only after removal of its toxic parotoid gland and skin). In fact, its meat is full of omega-3 fatty acids.
In Australia and Pacific Islands, cane toads are considered as pests as they are known to outcompete other native amphibians; and often prey on them triggering predator decline.
In its native environment, Cane toad’s predators include eel, various killifish species, some catfish species, bullet ants and road-snouted caiman among others.
Cane toad’s toxin does not affect meat ants. In fact, meat ants are able to kill them. Because of this scientists have considered to use meat ants to control cane toad population.
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