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Impurest's Guide to Animals #69 - Bipallium kewense

Another week in May, another issue of Impurest’s Guide to Animals and another missed opportunity to capture my nemesis, the feral Peacock, when it was drinking from my pond. Speaking of tricky creatures, we saw the Arboreal Salamander sneaking around the blog, as it eats its fellow salamanders. Anyway onto this weeks issue…

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Issue #69 - Bipalium kewense

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Kingdom – Animalia

Phylum – Platyhelminthes

Class – Turbellaria

Order – Tricladida

Family – Geoplanidae

Genus – Bipalium

Species – kewense

Related Species - Bipalium kewense is one of a multitude of carnivorous flatworms found across the globe (1)

Range - Considered invasive across it’s range in the United Stated, India, Europe and much of sub-Saharan Africa, it is at current unknown where Bipalium kewense originates from, although recent evidence suggests it might be somewhere in Southeast Asia

Invasion of the Hammerhead Slug

With an average length of 40cm, Bipalium kewense is a dark yellow colour, with a brown or black line running down the length of its body. The most distinctive feature however, is the anchor shaped head, earning the nickname of ‘the Hammerhead Slug’. The species moves, using a ‘creeping sole’ on its vernal side, in the same way a snail uses its muscular foot (2), although despite its more common name Bipalium kewense is a flatworm and not a mollusc. As well as the ‘creeping sole’ the vernal side also houses the ‘mouth’, which in addition to feeding, is also used in defecation to remove waste-products such as faeces.

All flatworms in the genus Bipalium are carnivorous, and specialize in feeding on earthworms. Prey is generally taken after rainfall, when it is most active, and tracked using chemical trails left in the worms wake. Prey is pinned to the ground by the flatworm, and covered in digestive enzymes that liquefy prey, before it is sucked up by the mouth. When attacked Bipalium kewense secretes a deadly neurotoxin called Tetrodotoxin, which often kills the predator, despite the amount of damage done to the flatworm.

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After an attack, if cut or broken in two, members of the genus Bipalium can regenerate into two separate worms. While this method of a-sexual reproduction is often used (3), mostly because Bipalium kewense readily feed on members of their own species, the worm can reproduce sexually and is a hermaphrodite, meaning after each sexual encounter each individual involved can lay a clutch of eggs.

Nature's Most Wanted: #1 - Brown Tree Snake

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The Brown Tree Snake (Boiga irregularis) (1) is a 2m long snake native to Australia, and is invasive to the island of Guam. While it is venomous, it is not the direct threat to people that lists this snake as an invasive species, rather its insatiable appetite for the native wildlife. Since its arrival in the mid 1950s the snake has hastened the extinction of two thirds of Guam’s native mammal species, half of the native reptile species and almost three quarters of native birds. Where there was once biodiversity rich forest only half a century ago, there is now only woodland literally crawling with snakes (4).

In addition to its destruction of the native wildlife, the Brown Tree Snake interferes with economic growth, often taking poultry from farms and damage to infrastructure, when it climbs telegraph poles and wraps around power-lines causing blackouts across entire electrical grids. It is estimated that, between damage to infrastructure, loss of livelihood and increased bio-security at both airports and docks, that the Brown Tree Snake costs the government close to 500 million US dollars a year.

The threat isn't contained just to Guam however; Brown Tree Snakes are inquisitive species, with little fear of predation and readily investigate dark spaces, even going as far as climbing on ships docked at port. So far strict bio-security has prevented the species from leaving Guam, although it is readily feared that the species will escape to other islands such as the Cocos or Hawaii. So far there has been little attempt to eradicate the population of snakes on Guam, although antibiotic laden mice are being used on US Naval ships, to catch any serpents that evade port security.

Bibliography

1 - www.arkive.org

2 - Ducey, P. K.; West, L. J.; Shaw, G.; De Lisle, J. (2005). "Reproductive ecology and evolution in the invasive terrestrial planarian Bipalium adventitium across North America". Pedobiologia 49 (4): 367

3 - Winsor, L. 1983. A revision of the cosmopolitan land planarian Bipalium kewense Moseley, 1878 (Turbellaria: Tricladida: Terricola). Zool. J. of the Linnean Soc. 79: 61-100.

4 - http://ftp.ma.utexas.edu/users/davis/375/LECTURES/L24/snake3.pdf

Picture References

1 - http://pics.davesgarden.com/pics/2008/07/27/fleurone/805a40.jpg

2 - http://edge.liveleak.com/80281E/u/u/thumbs/2013/Mar/25/9d62ae90612f_sf_3.jpg

3 - http://upload.wikimedia.org/wikipedia/commons/c/c9/Brown_tree_snake_Boiga_irregularis_2_USGS_Photograph.jpg

Wow toxic worms, and devil may care snakes, this actually turned out to be a fun issue to write. Speaking of fun we have two requests over the next fortnight from @ccraft and @cgoodness. But until then critic, comment and suggest future issues as well as making sure you check past issues in Impurest’s Bestiary

Many Thanks

Impurest Cheese

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