MarLIN

information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

Lagoon snail (Paludinella globularis)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.

Summary

Description

A small, globose snail that grows up to 2 mm high. The shell is glossy and semitransparent. The animal is pale grey and appears whitish through the shell. The tentacles are short and stubby with eyes seen as two black dots. It is often easily confused with juvenile Littorina saxatilis.

Recorded distribution in Britain and Ireland

Recorded from the Isle of Wight, the Fleet, North Devon, South Devon, Pembrokeshire, Cornwall and Isles of Scilly.

Global distribution

Primarily a Mediterranean species (absent from the Black Sea) which extends along Eastern Atlantic coasts from Madeira north to a limit on the south coast of England.

Habitat

Occurs in crevices, caves, under rocks and in lagoonal shingle, at or just above the water line. The caves are usually sheltered and the surface of the walls colonized by green and red algal films and soft crusts. Sites in caves are associated with lithologies which are foliated and fissile allowing the development of fissures and crevices.

Depth range

Not relevant

Identifying features

  • Tiny globose tarn-coloured shell.
  • Broad bifid snout.
  • Tentacles broad, joined and rounded, with a black eye in the centre of each left and right lobe.

Additional information

The pulmonate Otina ovata is a frequent associate of Paludinella globularis, in caves etc. In shingle, it often occurs with the pulmonates Ovatella myosotis and (slightly lower on the shore) Leucophytia bidentata, and the prosobranch Truncatella subcylindrica.

Kadolsky (2012) showed that the original description of type species of Paludinella littorina (originally described as Helix littorina Delle Chiaje, 1828), was most probably based on small specimens of Melarhaphe neritoides (Linnaeus, 1758). The original type description was, therefore, incorrect. In addition, Pfeiffer (1841) based the genus Paludinella on the taxonomic extension given to that name by Philippi (1841), i.e. a misidentified type species. Furthermore, Kadolsky noted that the correct name for specimens of P. littorina is, in fact, P. globularis.  Therefore, for specimens of Paludinella littorina of authors, non Delle Chiaje, Kadolsky restored the name Paludinella globularis and designated the latter as type species of Paludinella (Kadolsky, 2012; Bouchet, 2012).

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Biology review

Taxonomy

PhylumMollusca
ClassGastropoda
OrderLittorinimorpha
FamilyAssimineidae
GenusPaludinella
Authority(Hanley in Thorpe, 1844)
Recent SynonymsRissoa littorea Jeffreys, 1856Paludinella littorina (Delle Chiaje, 1828) sensu Philippi, 1841Cingula globularis Hanley in Thorpe, 1844

Biology

Typical abundanceModerate density
Male size rangemax. 2cm
Male size at maturityNo information
Female size rangemax. 2cm
Female size at maturityNo information
Growth formGlobose
Growth rateNo information
Body flexibilityNone (less than 10 degrees)
MobilityCreeper
Characteristic feeding methodSub-surface deposit feeder, Surface deposit feeder
Diet/food sourceDetritivore
Typically feeds onNo information
SociabilityGregarious
Environmental positionEpifaunal, Interstitial
DependencyNo information found.
SupportsNo information
Is the species harmful?No information

Biology information

Very little data on biology found. The animal crawls by alternately extending the front and rear halves of the foot forward, producing a shuffling gait. The foot is short and rounded. It is found at low to moderate densities in narrow, linear habitats.

Habitat preferences

Physiographic preferencesIsolated saline water (Lagoon), Open coast
Biological zone preferencesLower littoral fringe, Supralittoral, Upper littoral fringe
Substratum / habitat preferencesBedrock, Caves, Crevices / fissures, Gravel / shingle, Under boulders
Tidal strength preferencesVery Weak (negligible), Weak < 1 knot (<0.5 m/sec.)
Wave exposure preferencesSheltered
Salinity preferencesVariable (18-40 psu)
Depth rangeNot relevant
Other preferencesNo information
Migration Pattern

Habitat Information

Paludinella globularis is probably under-recorded due to its small size, inaccessible habitat and the similarity of its shell to that of Littorina saxatilis. An update on the distribution of Paludinella globularis (as littorina) was compiled by Light & Killeen (2001). Frequent molluscan associates are the pulmonate Otina ovata in the crevice or cave habitat, and the pulmonates Ovatella myosotis and Leucophytia bidentata and prosobranch Truncatella subcylindrica in shingle interstices. Other species particularly associated with Paludinella gobularis are the Isopoda Ligia oceanica in cave habitats (unless Ligia oceanica is excessively dominant, then Paludinella globularis is excluded), and Bdella mites in the interstitial habitat of the upper shore shingle or boulders (Light & Killeen, 2001).

Life history

Adult characteristics

Reproductive typeNo information
Reproductive frequency No information
Fecundity (number of eggs)No information
Generation timeInsufficient information
Age at maturityNo information
SeasonNo information
Life spanInsufficient information

Larval characteristics

Larval/propagule typeNo information
Larval/juvenile development No information
Duration of larval stageNo information
Larval dispersal potential No information
Larval settlement periodNo information

Life history information

-none-

Sensitivity reviewHow is sensitivity assessed?

Physical pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
High Low High Very low

Paludinella globularis would be removed upon substratum loss. Light & Killeen (1997) suggest that cliff instability may be the main threat to those colonies. Recoverability would be low because populations of the species are sparse.

High Low High Very low

Smothering could block shingle interstices, prevent movement of the snail and reduce the level of oxygenation. Recovery would be low because it probably lacks an aquatic dispersal phase and other colonies are distant.

Intermediate Moderate Moderate Very low

The species should be able to move through new silt and may be able to feed on it, so long as interstices remain clear.

Intermediate Low High Very low

Paludinella globularis is adapted to tolerate desiccation by its hard shell and operculum. However, the individuals that occur in crevices may not be able to tolerate twenty five percent increase in the time exposed to air. Those animals that are found in shingle will be largely sheltered from the effects of desiccation.

Low Moderate Low Very low

Increased or decreased emergence is likely to occur on a relatively long time scale during which the habitat and animals will probably be able to re-adjust.

Low Moderate Low Very low

Living at the high water mark, the species is inundated for only short periods so that increased water flow is unlikely to have a significant effect unless it is so great as to erode the substrate and wash animals away.

Intermediate Moderate Moderate Very low

The species reaches the northern limits of its distribution in England so may be particularly intolerant of reductions in temperature. The species would be protected from extremes in temperature where it lives in shingle or in crevices and caves.

Tolerant Not relevant Not sensitive Very low

The species will probably not be affected by a change in turbidity as it is not dependant on light availability.

Intermediate Low High Very low

Increased wave action may damage or wash away this species or move shingle, damaging the animal by abrasion.

No information Not relevant No information Not relevant

No information.

No information Not relevant No information Not relevant

No information.

High Very low / none Very High Low

Individuals living in caves and crevices are likely to be protected from physical disturbance. However, significantly increased pressure or trampling along high water mark at shingle sites could produce serious abrasion, which would damage the delicate shells.  Therefore, intolerance has been assessed as high.  Recovery would be low because populations are sparsely distributed.

High Low High Low

Habitat displacement would cause physical damage to animals.

Chemical pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
No information Not relevant No information Not relevant

No information.

Heavy metal contamination
No information Not relevant No information Not relevant

No information.

Hydrocarbon contamination
No information Not relevant No information Not relevant

Observations following the Sea Empress oil spill off Pembrokeshire found that the populations of Paludinella globularis were not affected (Light & Killeen, 1997). However, prosobranchs usually are affected by hydrocarbons.

Radionuclide contamination
No information Not relevant No information Not relevant

No information.

Changes in nutrient levels
No information Not relevant No information Not relevant

No information.

Low Low Moderate High

Paludinella globularis can tolerate a wide range of salinities as evidenced by its distribution in lagoons and on open shore. The species may not be able to withstand low salinity for long periods of time.

No information Not relevant No information Not relevant
No information.

Biological pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
No information Not relevant No information Not relevant

No information.

No information Not relevant No information Not relevant

No information.

Not relevant Not relevant Not relevant Not relevant

Not relevant.

High Low High Very low

Could cause huge disturbance and damage but is unlikely.

Additional information

Importance review

Policy/legislation

Wildlife & Countryside ActSchedule 5, section 9
Features of Conservation Importance (England & Wales)

Status

Non-native

Importance information

-none-

Bibliography

    Citation

    This review can be cited as:

    White, N. 2000. Paludinella globularis Lagoon snail. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. Available from: http://www.marlin.ac.uk/species/detail/2282

    Last Updated: 23/05/2000