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The Cane Toad or The Rhinella Marina.

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Common Name, Aliases and Scientific Name:

The rhinella marina, more commonly know as the cane toad, the gland, neo-tropical toad or the marina toad, is part of the true toad family, which is a species of toad, in which all members are known as toads. According to the dictionary.com neo-tropical literally means “belonging or pertaining to a geographical division comprising that part of the New World extending from the tropic of Cancer southward,” therefore the neo-tropical toad literally means a toad that lives somewhere from the tropic of Cancer and Southwards. The toad lives in South America and Australia, which are both South of the tropic of cancer. Therefore the toad is literally a neo-trophical toad. 

Origin of Invasive Species and Date and Place of Introduction:  

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The rhinella marina is native to Central and South America, but have been introduced to countries across Oceania and Australia. The toads were introduced to Australia in 1935, to help control cane beetle population. Roughly 3000 cane toads were released into sugar cane fields. There are now millions of cane toads, which thrive and live all over Northern Australia. The rhinella marina have spread all over Northern Australia, as they have few natural predators in Australia because they have few natural predators there. The rhinella marina live for up to 10 years, and reproduce at an incredibly fast rate. The female’s breed twice a year and can lay 8,000 – 35,000 eggs at a time, the eggs are laid in either stagnant or running water, with a water salinity of  up to 15%. Though only 0.5% of the eggs reach maturity, it takes 6-18 months for the toads to reach sexually maturity. Therefore, the toads have a high reproduction rate, few natural predators, and eat most things, including pet food left outside, allowing them to invade and travel quickly across large areas of land.

Negative Impacts on the Environment: 

The rhinella marina are very invasive and they exclude and reduce many numbers of different species. They are incredibly poisonous, therefore anything the tries to eat them normally are poisoned. The toads eat most things, therefore they reduce the amount of prey available for ot
her predators. They have really decreased the amount of honey bees there are in Australia, as they prey on them a lot. They competitively exclude other types of frog/toad and take over their niches by using resources and reproducing very quickly. The fact that only some birds, river rats, snakes, and centipedes prey one cane toads means that the toads population is not decreasing naturally, it’s just growing and growing.

#1
The toads have had many negative effects on the environment. Such as; killing many species, with the poison from the paratiod glands of their backs, due to this, they reduce their populations immensely. They have no natural predators in Australia and they have an abundance of food therefore they thrive. The toads will eat anything they can, their diet usually consists of; ants, crickets, honeybees, living insects and beetles. They have has a large effect on the adult goannas. 90% of the population were killed in the first year of the toads arrival, according to Dr. Greg Brown. The adult goannas eat small mammals and insects. Thus, due to the decrease in their population, their prey, (insects, beetles, small mammals and birds), begin to thrive. If the population of certain insects increase, such as the sugar cane beetles, then the sugar cane crops will suffer and then the farmers produce and income will suffer. Thus one can see that there are many knock on effects when just one animals population decreases. Therefore they reduce many species populations, as they have few natural predators, their population never decreases, meaning that other species cannot to increase again, cause their populations to decrease.

#2
The cane toads eats many different types of insects. This may indirectly affect plants also, as if the insects that pollinate plants, are all consumed, this means the plants will suffer. Therefore the cane toad causes a knock on effect. If the toads eat insects that pollenate plants, their population decreases, and thus the plants do not get pollenated and their populations are indirectly affected. 

#3
The Northern quoll is a native Australian cat like animal. 30-40% of them were previously found in North east Top end, in the norther territory of Cape York Peninsula and the Eninaleigh Uplands of Northern Queensland. In the past 10 years, nearly all of the northern quoll population has diminished. This is due to the rhinella marina preying, and poisoning them.

Northern Quell Distribution Map:                                                                             Cane Toad Distribution Map:

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Figure 1

Through looking at the maps above, one can see that where the rhinella marina have invaded, and their population has increased, the northern quell population has decreased. This is because the cane toad is an invasive species and instead of their population looking like this: (See Figure 1)

Their population is exponential and continues growing even when their prey’s population decreases, as they prey on almost anything, not just the northern quell. Therefore the northern quell is unable to increase it’s population again. 

 

Therefore, one can see that the Rhinella marina has had many negative effects on the environment and the biodiversity of Australia.

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Due to the lack of natural predators, the abundance of food and fast rate of reproduction the toads have now made it as far as Sydney.   

 

 

 

 

Physical Features:

The large amphibious cane toad has yellow/brownish dry, rough, warty skin. They have a bony  head. Around their eyes they have boney ridges that meet at their nose. They have four legs, their hind legs are webbed and their front legs are not.The toads can grow Screen Shot 2015-09-19 at 15.15.06up to 10-15 cm long and live for up to 10 years in the wild (5). The adult toads have large parotoid glands, behind their ear drums, (parotid means “behind the ear”), which emit poison (4, 6). The poison is known as bufotoxin and is squirted out of the gland when the toad comes into a dangerous situation. The toad builds up pressure behind the valve, which keeps the gland closed, and pushes the valve open, causing the poison to quirt out. The poison that is emitted from the large parotoid glands affects the breathing, blood pressure and beating pattern of the heart. This can result in paralysis, vomiting and salivation. (6,7)

Mating and the Rhinella Marina’s Niche: 

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 When mating the male toad will make a low-pitched-slow-trill noise to attract females. The adult toads are predators but the tadpoles are omnivorous.  The tadpoles are aquatic and therefore swim. The adult toads hop/jump around on land and in the water and sit up straight. (5,6,7).

 

The rhinella marina are mostly active at night, yet could potentially be active at any time of day.The adult rhinella marina are very territorial and will fight any other animal who tries to invade their territory.

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The toads normally migrate during wet season, as they need wet areas to live, and with the rain, there are an abundance of wet pockets and places to stay the night. During the dry season, the toads normally stay and live around creeks or pockets of water where there is water, and can live. A rhinella marina’s niche is normally located near or on a water source with shade, with tropical/sub-tropical humid, temperatures, where they can lay eggs and breed. Yet the toads are mostly nomadic and move around, especially during the wet season (8).

Control Methods #1 and #2: 

Many Australian citizens manually remove the toads, they use toad traps, and in some cases just go out into their back gardens at night and pick them up, and terminate them. Due to the lack of predators that the toads have, and their ability to reproduce very quickly, the few toad that you picked up last night, will be replaced by the next night. Therefore this technique does not work very well. It would work is the toad were able to reproduce, as then when one collected and exterminated toads, there would be one less toad out there. At the moment, there are many different companies, working on chemical suppressants, such as Team Bufo, to stop the toads from breeding. (8) Therefore, the main way the cane toads are being kept under control, is by Australian citizens collecting and exterminating the cane toads, and many companies are working on chemical suppressants to stop the toads from breeding. The rhinella marina’s population increase looks like this: 

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One can see, that even though the Australian people are using many different techniques, in order to stop the population increase and speed of the toad’s invasion, it is not working, as the toads population continues to increase, fast. 

 

 

 

Works Cited:

“Cane Toads, Cane Toad Pictures, Cane Toad Facts – National Geographic.”National Geographic. National Geographic, n.d. Web. 20 Sept. 2015. <http://animals.nationalgeographic.com/animals/amphibians/cane-toad/>. (5)

Paul. “Garden Guests: February 2009.” Garden Guests: February 2009. N.p., n.d. Web. 20 Sept. 2015.<http://gardenguests.blogspot.com.tr/2009_02_01_archive.html>.

Map of Cane Toads. Digital image. N.p., n.d. Web. 20 Sept. 2015. <http://lh4.ggpht.com/_evSTIFye5zM/SY_2DHzksdI/AAAAAAAAAfU/m2r-D-4wa1A/canetoaddist09.gif>. (9)

“Rhinella Marina | Mindo | Tropical Herping.” Rhinella Marina | Mindo | Tropical Herping. Tropical Herping, n.d. Web. 20 Sept. 2015. <http://www.tropicalherping.com/publications/books/mindo/rhinella-marina.html>. (1)

“Avian Fact Sheet.” Cane Toad Facts Sheet. (2004): n. pag. Pest Tales. Web. 20 Sept. 2015.<http://www.pestales.org.au/activities/CaneToad_factsheet.pdf>. (2)

“Australian Government. “The Biological Effects, including Lethal Toxic Ingestion, Caused by Cane Toads (Bufo Marinus).” The Biological Effects, including Lethal Toxic Ingestion, Caused by Cane Toads (Bufo Marinus). Australian Government – Department of Environment., 12 Apr. 2005. Web. 20 Sept. 2015. <https://www.environment.gov.au/biodiversity/threatened/key-threatening-processes/biological-effects-cane-toads>. (3)

“Cameron, Elizabeth. “Australian Museum.” Cane Toad –. Australian Museum, 1 Dec. 2014. Web. 20 Sept. 2015. <http://australianmuseum.net.au/cane-toad>. (4)

“The Most-Traveled Cane Toad.” Web Page. N.p., n.d. Web. 20 Sept. 2015. <http://bioweb.uwlax.edu/bio203/s2009/gutierre_marc/poison.htm>. (6)

“Cane Toad: The Animal Files.” Cane Toad: The Animal Files. N.p., n.d. Web. 20 Sept. 2015.<http://www.theanimalfiles.com/amphibians/toads/cane_toad.html>. (7)

“Current Methods to Cane Toad Control.” Current Methods to Cane Toad Control. SBI, n.d. Web. 20 Sept. 2015. <http://www.canetoadsinoz.com/cane-toad-control.html>. (8)

“Towie, Narelle. “Cane Toad Poison Banned.” Perth Now. Sunday Times., 23 May 2009. Web. 20 Sept. 2015. <http://www.perthnow.com.au/news/cane-toad-poison-banned/story-e6frg12c-1225715177178>. (10)

“Cane Toad.” Cane Toad. N.p., n.d. Web. 20 Sept. 2015. <http://kids.nationalgeographic.com/animals/cane-toad/>. (11)

“Cane Toads Are Killing Crocodiles in Australia.” Mongabay Environmental News. N.p., 30 July 2008. Web. 20 Sept. 2015. <http://news.mongabay.com/2008/07/cane-toads-are-killing-crocodiles-in-australia/>. (12)

“Agriculture .” Cane Toad. N.p., n.d. Web. 20 Sept. 2015. <http://agriculture.vic.gov.au/agriculture/pests-diseases-and-weeds/pest-animals/a-z-of-pest-animals/cane-toad>. (13)

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