Looping snail (Truncatella subcylindrica)
One juvenile crawling shell and 5 adults of Truncatella subcylindrica. Also one shell of Paludinella litorina.
Photographer: Dennis R. Seaward Copyright: Dennis R. Seaward
Line drawing of Truncatella subcylindrica.
Photographer: Copyright: Dr R.S.K. Barnes
Two adult Truncatella subcylindrica, one crawling.
Photographer: Dennis R. Seaward Copyright: Dennis R. Seaward
Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help
| Researched by | Nicola White | Refereed by | Dennis R. Seaward |
| Authority | (Linnaeus, 1767) | ||
| Other common names | - | Synonyms | - |
Summary
Description
A buff-coloured snail that grows up to 5 mm high. The animal has a cylindrical snout ending in a rounded mouth disc. It has a peculiar looping gait.
Recorded distribution in Britain and Ireland
Recorded from Pagham Harbour, West Sussex; The Solent, Isle of Wight, The Fleet, Dorset and St Mawes Bay, Cornwall.Global distribution
From the Channel coasts of France and Britain to the Mediterranean, the Black Sea, and on the Canaries, Madeira and Azores.Habitat
Found in shingle amongst rotting vegetation and fine sediment at a depth of 15 cm, at high water mark and more rarely in muddy habitats under stones at the high water mark. It is often associated with the plants Suaeda maritima, Suaeda vera and Atriplex (Halimione) portulacoides.Depth range
-Identifying features
- The juvenile has a typical spire-shaped shell; later whorls are parallel-sided until maturity when the tapered part is broken off, leaving a suture line. The adult shell is thus truncated and more or less cylindrical.
- Buff-coloured, 5 mm high.
- Animal with cylindrical snout ending in a rounded mouth disc.
Additional information
Abscission of the earlier part of the shell is presumably an adaptation to an interstial habitat.
The taxonomy of the Gastropoda has been recently revised (see Ponder & Lindberg 1997, and Taylor 1996). Ponder & Lindberg (1997) suggest that Mesogastropoda should be included in a monophyletic clade, the Caenogastropoda.
Listed by
- none -
Biology review
Taxonomy
| Phylum | Mollusca | Snails, slugs, mussels, cockles, clams & squid |
| Class | Gastropoda | Snails, slugs & sea butterflies |
| Order | Littorinimorpha | |
| Family | Truncatellidae | |
| Genus | Truncatella | |
| Authority | (Linnaeus, 1767) | |
| Recent Synonyms | ||
Biology
| Typical abundance | Moderate density | ||
| Male size range | up to 5mm | ||
| Male size at maturity | |||
| Female size range | Very small(<1cm) | ||
| Female size at maturity | |||
| Growth form | Cylindrical | ||
| Growth rate | Data deficient | ||
| Body flexibility | |||
| Mobility | |||
| Characteristic feeding method | Sub-surface deposit feeder, Surface deposit feeder | ||
| Diet/food source | |||
| Typically feeds on | Vegetable detritus and small algae | ||
| Sociability | |||
| Environmental position | Epifaunal | ||
| Dependency | Independent. | ||
| Supports | Not relevant | ||
| Is the species harmful? | Data deficient | ||
Biology information
It has a peculiar looping gait and moves along by alternately attaching the foot and snout to the substratum (Seaward, 1988). The species is found at moderate densities in narrow, linear habitats.
Habitat preferences
| Physiographic preferences | Estuary, Isolated saline water (Lagoon) |
| Biological zone preferences | Lower littoral fringe, Upper littoral fringe |
| Substratum / habitat preferences | Gravel / shingle, Mud |
| Tidal strength preferences | Very Weak (negligible) |
| Wave exposure preferences | Sheltered |
| Salinity preferences | Variable (18-40 psu) |
| Depth range | |
| Other preferences | No text entered |
| Migration Pattern | Non-migratory / resident |
Habitat Information
Formerly known from 12 sites in Britain, from Porthcurno along the south coast to the rivers Orwell and Deben, Suffolk. Presently known to be living in only five locations. It is a southern species which reaches its most northerly distribution in Britain. Paludinella globularis (as littorina), Ovatella myosotis and Leucophytia bidentata are associates.Life history
Adult characteristics
| Reproductive type | Gonochoristic (dioecious) | |
| Reproductive frequency | No information | |
| Fecundity (number of eggs) | No information | |
| Generation time | Insufficient information | |
| Age at maturity | Insufficient information | |
| Season | Insufficient information | |
| Life span | Insufficient information |
Larval characteristics
| Larval/propagule type | - |
| Larval/juvenile development | Oviparous |
| Duration of larval stage | Not relevant |
| Larval dispersal potential | <10 m |
| Larval settlement period | Insufficient information |
Life history information
Egg capsules are laid of 0.75-0.80mm diameter, which are spherical and surrounded by a thick wall. Each capsule contains one egg and they are attached singly to pieces of detritus in the habitat in which the adults live. Small snails are hatched with a shell of 0.65mm (Fretter & Graham, 1978)Sensitivity review
The MarLIN sensitivity assessment approach used below has been superseded by the MarESA (Marine Evidence-based Sensitivity Assessment) approach (see menu). The MarLIN approach was used for assessments from 1999-2010. The MarESA approach reflects the recent conservation imperatives and terminology and is used for sensitivity assessments from 2014 onwards.
Physical pressures
| Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
| High | Low | High | Very low | |
| The species would be removed with substratum loss and may be damaged during the process. It has low recoverability as it lacks an aquatic dispersal phase and living populations are only known from three locations in the UK. | ||||
| High | Low | High | Very low | |
| Smothering could block shingle interstices and prevent movement of the snail and reduce the level of oxygenation. Recovery would be low because it lacks an aquatic dispersal phase and living populations are only known from five locations in the UK. | ||||
| Tolerant* | Not relevant | Not sensitive* | Very low | |
| Truncatella subcylindrica lives in estuaries and lagoons amongst fine muddy sediment so would be able to tolerate increased siltation. Indeed, some increased siltation may be beneficial to feeding as it is a deposit feeder, so long as interstices remain clear. | ||||
| No information | ||||
| Low | Moderate | Low | Very low | |
| The mollusc is adapted to avoid desiccation by having a hard shell and operculum. Where it is interstitial, the species would also be protected from desiccation by the depth of sediment above it and where the species is epifaunal would avoid desiccation by hiding in crevices or under stones. | ||||
| 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. | ||||
| No information | ||||
| Low | Moderate | Low | Very low | |
| Living at 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 materials and animals. | ||||
| No information | ||||
| Intermediate | Moderate | Moderate | Very low | |
| The degree of temperature tolerance of Truncatella subcylindrica is not known. The species will be sheltered from temperature extremes to some extent by its hard shell and by its interstitial habitat. However, the species may be intolerant of decreases in temperature as it is at the northern limit of its distribution. | ||||
| No information | ||||
| Tolerant | Not relevant | Not sensitive | Very low | |
| The species is unlikely to be affected by a change in turbidity as it does not depend on light availability for feeding and some populations are found interstitially where light cannot penetrate. | ||||
| No information | ||||
| Intermediate | Low | High | Very low | |
| The high water mark habitat means that the species is only subject to wave action for short periods. However, increased wave action may damage or wash it away, or move shingle damaging the animal by abrasion. | ||||
| No information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| High | Very High | Very low | ||
| Any factor causing movement of shingle where the animal lives, by natural (e.g. wave action) or human (e.g. trampling) means would be likely to damage infauna by abrasion and crushing. | ||||
| High | Low | High | Very low | |
| Habitat displacement would cause damage to animals. | ||||
Chemical pressures
| Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
| High | Low | High | Moderate | |
| Exposure of spermatocytes of the species to dibutyltin(IV) and tributyltin(IV) caused structural damage in the chromosomes in 24 hours at 0.0001 moles per litre (Vitturi et al., 1992). | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| Low | Low | Moderate | Very low | |
| The species occurs in lagoons and estuaries so is tolerant of reduced and fully saline conditions. However, the species may not be tolerant of low salinities for long periods of time. | ||||
| No information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
Biological pressures
| Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| No information | Not relevant | No information | Not relevant | |
| Insufficient information | ||||
| Not relevant | Not relevant | Not relevant | Not relevant | |
| NR | ||||
| High | Low | High | Very low | |
| Would cause huge disturbance and damage but is unlikely. | ||||
Additional information
Importance review
Policy/legislation
Status
| National (GB) importance | Not rare/scarce | Global red list (IUCN) category | - |
Non-native
| Native | - | ||
| Origin | - | Date Arrived | - |
Importance information
The assemblage is of low diversity and biomass occupying only a small proportion of the space available. It is unlikely to provide a unique food source, although a nemertean predator Prosorhochmus claparedii is recorded from the same niche at the Fleet (R.S.K. Barnes, per. comm.)Bibliography
Barnes, R.S.K., 1994. The brackish-water fauna of northwestern Europe. Cambridge: Cambridge University Press.
Fretter, V., & Graham, A., 1978. The Prosobranch Molluscs of Britain and Denmark. Part 3. Journal of Molluscan Studies, Supplement 5, 137.
Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]
Killeen, I.J. & Light, J.M., 1998. A discovery of Truncatella subcylindrica living in Cornwall. Journal of Conchology, 36, 50-51.
Ponder, W.F. & Lindberg, D.R., 1997. Towards a phylogeny of gastropod molluscs: an analysis using morphological characters. Zoological Journal of the Linnean Society, 119, 83-265.
Seaward, D.R., 1988. Locomotion in Truncatella subcylindrica. Journal of Conchology, 33, 49.
Seaward, D.R., 1991. Caecum armoricum. In British Red Data Book. 3. Invertebrates other than Insects (ed. J.H. Bratton). Peterborough: Joint Nature Conservation Committee. 253p.
Taylor, J.D.(ed.), 1996. Origin and Evolutionary Radiation of the Mollusca. Oxford: Oxford University Press.
Vitturi, R., Mansueto, C., Catalano, E., Pellerito, L., & Girasolo, M.A., 1992. Spermatocyte chromosome alterations in Truncatella subcylindrica following exposure to dibutyltin (IV) and tributyltin(IV) chlorides Applied Organometallic Chemistry, 6, 525-532.
Datasets
Conchological Society of Great Britain & Ireland, 2017. Mollusc (non-marine): 1999 Atlas Dataset for Great Britain and Ireland. Occurrence dataset: https://doi.org/10.15468/gbawsj accessed via GBIF.org on 2018-09-25.
Conchological Society of Great Britain & Ireland, 2017. Mollusc (non-marine): Compilation of records of rare and scarce species for Great Britain and Northern Ireland. Occurrence dataset: https://doi.org/10.15468/e9fnjh accessed via GBIF.org on 2018-09-25.
Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) data for Great Britain and Ireland - restricted access. Occurrence dataset: https://doi.org/10.15468/4bsawx accessed via GBIF.org on 2018-09-25.
Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) records for Great Britain and Ireland. Occurrence dataset: https://doi.org/10.15468/aurwcz accessed via GBIF.org on 2018-09-25.
Conchological Society of Great Britain & Ireland, 2018. Mollusc (non-marine) data for Great Britain and Ireland. Occurrence dataset: https://doi.org/10.15468/6dexp9 accessed via GBIF.org on 2018-09-25.
Kent & Medway Biological Records Centre, 2017. Land molluscs: Records for Kent. Occurrence dataset: https://doi.org/10.15468/zintf2 accessed via GBIF.org on 2018-10-01.
Kent Wildlife Trust, 2018. Kent Wildlife Trust Shoresearch Intertidal Survey 2004 onwards. Occurrence dataset: https://www.kentwildlifetrust.org.uk/ accessed via NBNAtlas.org on 2018-10-01.
NBN (National Biodiversity Network) Atlas. Available from: https://www.nbnatlas.org.
OBIS (Ocean Biodiversity Information System), 2023. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2023-03-30
Citation
This review can be cited as:
Last Updated: 03/06/2008
