17th January 2015 (weekly review)

I can’t believe it’s been a full week since, well, last week. It’s gone by very quickly.

I’ve managed to add a further 3 species to my snail tally, bringing the overall total to seven species. I’ve also been photographing anything else snail-related that I’ve come across, which includes slugs (succumbing to pressure from my Twitter followers) and snail-predators (showing the vital part snails play in ecosystems).

Here are my three new snails from the past seven days:

Vallonia costata, The Ribbed Grass Snail (or, rarely, the Costate Vallonia)

The genus Vallonia comprises three species in the UK, of which I have found V. costata the most common/easiest to find, as well as the most distinctive of the group. The UK Vallonia  species are a pleasant whitish-ivory colour, and all are under 3mm fully grown. Fresh, mature and unworn V. costata can be easily distinguished from the others due to the stout ribbing of the shell. In fact the specific name – costata – comes from the Latin ‘costa’ meaning ‘rib’. ‘Vallonia’ apparently comes from the Latin for ‘from the vale’ or ‘shallow valley’, presumably as a reference to the grassy habitats where this genus can be found.

V. costata is a species of calcareous grassland; usually dry in my experience. The most reliable spot I know for the species is in Potton churchyard, Bedfordshire, where I find it commonly on top of a particular tomb – I imagine the stonework is calcium-rich. The photo below has been the most popular photo I have yet shared on Twitter; I think people appreciate a sense of scale when dealing with very small species.

Vallonia costata

Oxychilus draparnaudi, Draparnaud’s Glass Snail

Last week I found Oxychilus alliarius, the Garlic Snail, the smallest of the four UK Oxychilus species. This week, I bring you Oxychilus draparnaudi, the largest UK species in the genus at a maximum of around 16mm. This snail does not produce a garlic scent at all (which can help distinguish it from O. alliarius and O. navarricus) and has a noticeably smaller umbilicus than O. cellarius.

Oxychilus draparnaudi is a non-native species within the UK, but it seems to been present here for some time; I haven’t found any first dates of discovery. It also appears to be relatively benign introduction or, at least, I haven’t found reference to it causing a nuisance.

In my experience, Oxychilus draparnaudi is usually found in gardens, parks and other urban and semi-urban areas. It may be that it does particularly well in areas with human disturbance.

Oxychilus drapa

Trochulus striolatus, The Strawberry Snail

Trochulus striolatus is another very common species. I’ve found it mainly around the flowerbeds and the bases of hedges in urban areas and other damp and/or humid areas; the first one I ever identified was crawling across my doorstep after rain. Its common name ‘The Strawberry Snail’ is probably derived from its habitat; living amongst low plant growth such as strawberries. Its scientific specific name ‘striolatus’ come from the Latin for ‘bearing narrow markings’ which probably refers to the coarse growth lines on the shell.

Juvenile Trochulus striolatus bear a few scattered hairs on the shell that are lost once it matures. There are two other species in the genus Trochulus in the UK, T. hispidus and T. sericeus. These are both smaller at full size, and both often retain hairs on the shell into adulthood.

Strawberry Snail

Also during the week I bumped into two species of slug, Lehmannia marginata, The Tree Slug, and Arion intermedius, The Hedgehog Slug.

Lehmannia marginata

Hedgehog slug

I also found a snail-specific predator, Silpha atrata or the ‘Black Snail Beetle’. Silpha atrata has a noticeably narrow head and neck compared to the width of its body. This is so that it can reach its head into the mouth of occupied shells to feed on the snail inside. Lovely.

Silpha atrata

Once again, if you’re not following me on Twitter please consider doing so at @UKSnailTrail.

For further, more in-depth information on snails and other molluscs, please check out the website of the Conchological Society of Great Britain and Ireland.

2 thoughts on “17th January 2015 (weekly review)

    • They are not particularly active in winter, unless they are in a slightly warmer and more humid micro-climate such as amongst leaf-litter. They’ll get more active in warmer and damper weather.

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