The War Of The Snails, Round Three: Down But Not Out

Today’s post is by Bryony from the Visitor Team at Manchester Museum. We are not experts, but we are people with a passionate interest in the museum and its objects. We each bring our own insight into Manchester Museum and its collections.

For more about zoology and nature at Manchester Museum, please visit the Curator’s blogNature Manchester.

The War Of The Snails, Round Three: Down But Not Out

You may have read my recent blog post about the little local Partula and Achatinella snails. You may also have read the continuation with the African giant land snail. If you haven’t, here is Part One and Part Two.

So what snail will make up Part Three?

A predatory species, a snail-eating snail, called the rosy wolfsnail.

Rigby11
Available at: https://wheredreamsbecomereal.wordpress.com/2013/05/19/rosy-wolfsnail/

It even looks evil. Euglandina rosea, or the rosy wolfsnail.

Biological control – that is, introducing a new predator to eat the introduced species and keep their numbers down – sometimes works very well. If the introduced predator has a very specific range of animals it eats, it will leave the local species alone and only eat the invasive species – an environmentalist’s dream! Control without the use of pesticides or any measures that mess with the environment? This was the ideal, but it could also go badly wrong, particularly if they chose the wrong predator.

They chose wrongly.

WARNING: not for the faint-hearted, but worth watching for a few seconds at least to see it waving its mouthparts menacingly around before it devours the slug.

The rosy wolfsnail had more food than it could have dreamed of, but it rarely ate the unfeasibly large African giant land snail, instead preferring smaller morsels – our Partula and Achatinella species.

Below is a list the classifications of threatened species, and a quick description of what they really mean (in general; this is simplified to just the main deciding criteria, although other factors can affect the classification):

Vulnerable – This species has lost more than 50% of its population in the past 10 years (or 3 generations, if that is longer).

Endangered – This species has lost more than 70% of its population in the past 10 years (or 3 generations, if that is longer).

Critically Endangered – This species has lost more than 90% of its population in the past 10 years (or 3 generations, if that is longer).

Extinct in the Wild – This species has lost 100% of its population in the wild, existing only in zoos.

Extinct – This species has lost 100% of its population, no longer existing at all.

Since the rosy wolfsnail’s introduction in 1974, there has been a terrible impact on the local snails. Of the 72 Achatinella species, 51 are Extinct, and the remaining 21 are Critically Endangered with many most likely Extinct In The Wild. Of the 100 original Partula varieties, 50 are Extinct, with a further 14 are classified as Extinct in the Wild, with many others being classified as at least Vulnerable.

The fact that so many species have (hopefully) survived is only thanks to the fast action of conservationists who took these snails into captivity (for example, at the University of Hawaii, or at Chester Zoo), as well as the establishment of the world’s tiniest nature reserve on the island of Moorea, a regularly patrolled 12m x 9m square.

Rigby12
Available at: https://www.zsl.org/sites/default/files/styles/wysiwyg/public/media/2015-08/Reserve-crop.jpg?itok=4F5aM8mN

The world’s smallest government-funded nature reserve, in the Te-fati Valley on Moorea.

And that’s why these small snails are on display in the museum. So next time you’re in, show them a little love and remember – small doesn’t mean insignificant!

Our little Partula and Achatinella snails (circled in yellow), on display in the Variety Of Life case, Living Worlds, Manchester Museum.

Bryony Rigby

P.S. Want to find out more?
http://www.arkive.org/partula-snails/partula-spp/
http://hbs.bishopmuseum.org/endangered/ext-snails.html
https://books.google.co.uk/books?id=GU-iBQAAQBAJ&pg=PA9&lpg=PA9&dq=polynesian+culture+partula&source=bl&ots=O9_OLHv2U0&sig=XzsZm5w9u76VLFdHh4KTYPJQfl4&hl=en&sa=X&ei=6dNRVbCpH6WcygPEk4CgCg&ved=0CDQQ6AEwAw#v=onepage&q=polynesian%20culture%20partula&f=false
http://www.molluscs.at/gastropoda/terrestrial.html?/gastropoda/terrestrial/euglandina.html
http://www.academia.edu/2880305/THE_CONSERVATION_AND_MANAGEMENT_OF_ENDANGERED_OAHU_TREE_SNAILS_GENUS_ACHATINELLA_

For more about zoology and nature at Manchester Museum, please visit the Curator’s blogNature Manchester.

Read more by Bryony from the Visitor Team;
The War of the Snails, Round Two: The Heavyweight
The War of the Snails, Round One: The Home Favourite
A Plethora of Penguins
Halloween Special! Death and the Hawk Moth
Kiwi and Egg Syndrome

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