Monday, 15 June 2009

Eungella's Big Three

The name means 'mountain in the cloud', but it's not always cool and wet at Eungella. This time it was cool cold and dry. Excellent weather for keeping mosquitoes and leeches at bay but not so good for photographing snails.

Whereas Africa has its Big Five — the large mammals that tourists want to see — Eungella has its Big Three. Oh, yes, people may claim they're visiting Broken River to watch platypus but I think we all know what they're really here for — the snails Sphaerospira informis (Camaenidae), Pandofella whitei (Caryodidae) and Fastosarion superba (Helicarionidae).

I could only tick off one from my list this time: Fastosarion. These big semi-slugs like to spend the day in the rolled bases of palm fronds, where they are protected from desiccation. That's where I found these two.

Helicarionids are characterised by a thin, often transparent shell and a tail that looks as though it is folded vertically. Most species are semi-slugs in which the shell covers the organs of the visceral mass but is too small to accommodate the head and foot. Helicarionid semi-slugs are common in closed forests of the east coast but few are as spectacular as F. superba. (It's a relative measure.)

These two were rather sluggish. (Sorry.) Denis at Nature of Robertson has photos of a southern NSW helicarionid out and about. Imagine a semi-slug about three times as long and you've got the idea!


Denis Wilson said...

Hi Snail
Great to see you living up to your name - as soon as you have arrived in FNQ.
Nice Helicarionids. Thanks for the link to mine.
Nice to see a real tropical Semi-slug, complete with its ridiculous "french Beret" style of shell. Makes you wonder why they bother at all, doesn't it?


Looks like the shell is partially covered by flaps of mantle. No?

Snail said...

Denis, these are the first snails I've seen all trip. Mind you, I haven't been looking that hard! Once I've settled in, it'll be a different story.

That half-shell must be working for them because there are plenty of helicarionid semi-slugs. Overseas, it's found in other families (e.g. Vitrinidae). Damned if I know why, though.

Aydin, yes, at rest the shell is partially to almost completely covered by extended mantle lobes. They usually retract when the animal's active.

In some genera, like Parmacochlea from NQ, the shell is a flat plate and the lobes are sutured so all you can see is a window of yellow shell.