Culprit 1: Bufo Marinus

 One example is Bufo Marinus, also known as the cane toad, was introduced into eastern Australia in 1935, via intentional methods, to combat the spread of the cane beetle, which was accidentally introduced into the sugar cane fields with devastating results. The adult cane toad is on average, 106.25grams, and is 5.91-9.37 long. They breed once yearly, giving birth to about 30,000 tadpoles and the tadpoles grow into adult hood in roughly 45-55 days. The Invasive Species Specialist Group has also voted these toads #16 of 100 worst invasive species.

Even though the cane toad is a natural enemy to the cane beetle, and was brought to Australia for just that reason, they never actually did much for that purpose. They went after the easier meals, such as native bird eggs, frogs, and insects, instead of the cane beetles, which were usually high up eating the sugar cane plants. Several species of native birds, one example of which is the northern quoll, saw considerable declines in their local populations.

If the cane toads’ size and massive spawning abilities were not enough of an advantage, it is also highly poisonous. They excrete an extremely potent toxin through their backs when threatened. Because of this, any animal that may eat a cane toad dies. Any fish, which eats a cane toad tadpole, dies. As a result, the local goanna (a large native Australian lizard) and snake populations have dramatically declined. Snake species, which have been placed on the endangered species list because of the cane toad, include the tiger snake, the red-bellied black-eyed snake, and the death adders. They can spray the toxin up to a meter (39.37inches) away, and can cause major eye irritation, partial/temporary blindness. This can also cause indirect illnesses in many animals because the Cane toads’ toxins can contaminate small bodies of water, like the water bowls for pets. The toad’s poison has been linked to several human deaths, primarily children, caused by ingesting the tadpoles, or extreme reactions to the toxins accidentally absorbed through the skin after being sprayed.

Amazingly, the cane toad has rapidly evolved longer legs, directly related to their ability to travel farther and as a consequence 10% of the leading edge of cane toads have developed Arthritis. Local snakes species have evolved smaller mouths so that they could not swallow the adult cane toads. Some bird species have developed a technique for eating them and avoid being poisoned, they have be witnessed flipping dead cane toads on their backs and eating from the belly, avoiding any toxic organs, or only receiving a slight poisoning, but not enough to die. This is absolutely amazing by any evolutionary standard.

This nuisance has not gone unnoticed by the human population. The Australians have begun programs, local and government orchestrated to eradicate them. Local plans involve smashing them for fun, using them as cricket balls, turning the bodies into coin purses, or any other kind of fashion statement they see fit. Government organized plans include biological warfare and widespread hunts for them. The government hopes to create a virus, which can only kill the tadpoles of the cane toads, and does not infect any local frog species. The virus they are designing, called Bohle Irradovirus (BIV), is programmed to “turn off” the gene that turns the tadpoles into sexually mature adults. This would essentially and efficiently eliminate the entire affected population.  

Bufo Marinus, in only 74 years, has gone from the initial released population of only 3,000 to a massive 200,000,000, and has spread toward central Australia. It has been estimated that cane toads can migrate up to 25miles a year. This movement does not explain their rapid progress across Australia. It is explained through the toads birthing habits, giving birth to their tadpoles in rivers and streams, where the babies are swept up in the current and carried until they are old enough to survive on land. They have also been unknowingly transported via trucks or trains alongside the locally exchanged produce/resources.

As for environmental damage, the cane toads are capable of clearing up to 100-yard radii of all edible nutrients around water holes and as a result starve themselves afterward. They also contaminate any small body of water they come into contact with because of the toxin they secrete. This means that that area is now barely livable to most species standards and the local inhabitants are forced to move in search of food. Since the average cane toad lives up to 5 years they must move once every 1-2 years in search of a new food source.