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• Physa fontinalis (Linnaeus 1758) Common bladder snail

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© Dr Roy Anderson

© Dr Roy Anderson

A small, yellow-brown, sinistral shell with short, blunt spire. Shell slippery and highly polished. The animal is grey and outgrowths of the mantle partly cover the shell. These have finger-like lobes or digitations. Widespread and common.

Key characteristics

• A small, sinistral, yellow-brown shell
• Spire short and blunt
• Animal dark grey with finger-like lobes or digitations of the mantle partly covering the shell in life
• Shell fragile, polished and slippery

Size

8-12 mm.

World Distribution

This species has a wide distribution in the western Palaearctic, but like Aplexa hypnorum, confusion with allied forms makes the eastern limits of its distribution uncertain. The range is probably Eurasian Boreo-temperate (55). Several ‘species’ found in North America may be conspecific in which case the range could be Circumpolar Boreo-temperate.

GBIF distribution map [open in new tab]

Irish Distribution

Widespread throughout Ireland but sparser in the west and north.

Ecology

• A fragile but active species usually of clear, weedy and slow-flowing or stagnant waters such as canals, slow rivers and moderate-sized lakes, or the sheltered margins of larger lakes
• Tolerant of moderate eutrophication
• The effect of incursions by alien Physidae has not been assessed but Kerney (1999) observed little effect upon populations in Britain, except at organically polluted sites

Red List status

• Least concern (lc).

Wikipedia link

Wikipedia page for Physa fontinalis