Aplexa hypnorum, common name the moss bladder snail, is a species of small air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Physidae, a family which are sometimes known as the bladder snails.
As is true of all physids, the shell is sinistral, or left-handed. The species inhabits temporary water bodies and occurs from Europe to Asia.
The distribution of this snail is Holarctic
. It is known to occur in:
This species inhabits very shallow ponds and ditches, usually ones that dry out periodically.
is translucent and pale brownish in color. It is elongate with a high spire
and a narrow aperture
. The maximum length of the shell is about 13 mm.
In contrast to the shell, the soft parts of the animal are black or dark grey. The tentacles are long and narrow.
This is a surprisingly active and lively snail.
Although the animals themselves die when a temporary pond dries out, the eggs are extremely resistant to desiccation.
- Janus, Horst, 1965. "The young specialist looks at land and freshwater molluscs", Burke, London
- Arthur Adams, Henry Adams, 1858, The Genera of Recent Mollusca, J. Van Voorst, Plate LXXXIV, nr 2&2a.
- Photo and information from Denmark
- Older records, misidentifying Aplexa elongata as Aplexa hypnorum in Utah, USA
- From Germany, with shell photo available