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

A brachiopod (Novocrania anomala)

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

Summary

Description

Brachiopods are bivalved animals unrelated to molluscs. Novocrania anomala looks rather like a limpet with a low conical shell or valve attached to a hard surface. The shell is oval in vertical view and up to 1.5 cm long. The other valve is cemented to the surface beneath the animal. The shell surface is smooth and has fine concentric lines. Shell colour is pale grey, yellow or white and is overlaid with a thin brown periostracum.

Recorded distribution in Britain and Ireland

From the Firth of Clyde up the west coast of Scotland including the Hebrides, Shetland, the south coast of England and the Isle of Man. In Ireland along the south coast, the north-west and the north-east.

Global distribution

From the Canary Isles, the Britain Isles, the Faeroe Isles, Norway, Iceland and Spitzbergen.

Habitat

Typically inhabits rocky current-swept bottoms in moderately shallow water. The species is not very tolerant of wave exposure and so is found in deep water or in sheltered fjordic sea lochs.

Depth range

15-1500

Identifying features

  • Ventral valve is cemented to substratum.
  • Dorsal valve conical with the apex posterior to the midpoint.
  • Valves lack articulation.
  • There is no pedicle.
  • Calcium carbonate based shell.

Additional information

Unusually for the inarticulate brachiopods, the shell contains calcium carbonate. In brachiopods the valves of the shell are dorso-ventral whereas in molluscs the valves are lateral.

Listed by

- none -

Further information sources

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Biology review

Taxonomy

PhylumBrachiopoda
ClassCraniata
OrderCraniida
FamilyCraniidae
GenusNovocrania
Authority(Müller, 1776)
Recent SynonymsCrania anomala (Müller, 1776)Neocrania anomala (Müller, 1776)

Biology

Typical abundanceModerate density
Male size range0.23 - 15mm
Male size at maturity
Female size rangeSmall(1-2cm)
Female size at maturity
Growth formBivalved
Growth rateData deficient
Body flexibilityNo information
MobilitySessile
Characteristic feeding methodActive suspension feeder
Diet/food sourcePlanktotroph
Typically feeds onseston
SociabilityNo information
Environmental positionEpifaunal
DependencyNo information found.
SupportsNo information found
Is the species harmful?No

No text entered

Biology information

The lophophore forms the main feeding organ. Mucus is not used in particle capture, only for transport. Novocrania anomala exhibits some degree of particle selectivity. There is a complex mechanism for particle rejection. There is little information on growth rate except that it is believed to be represented by an exponentially declining curve but dependent on depth, food, population density etc. Growth after the first year is slow. Four or five year classes can be identified. Novocrania anomala is capable of recovery from considerable damage to the shell and soft tissue. The adults can be maintained quite well in aquaria and are generally hardy organisms.

Habitat preferences

Physiographic preferencesOpen coast, Offshore seabed, Sea loch / Sea lough, Open coast, Offshore seabed, Sea loch / Sea lough
Biological zone preferencesLower circalittoral, Lower infralittoral, Upper circalittoral, Lower circalittoral, Lower infralittoral, Upper circalittoral
Substratum / habitat preferencesBedrock, Large to very large boulders, Other species, Small boulders, Bedrock, Large to very large boulders, Other species, Small boulders
Tidal strength preferencesModerately Strong 1 to 3 knots (0.5-1.5 m/sec.), Very Weak (negligible), Weak < 1 knot (<0.5 m/sec.), Moderately Strong 1 to 3 knots (0.5-1.5 m/sec.), Very Weak (negligible), Weak < 1 knot (<0.5 m/sec.)
Wave exposure preferencesExtremely sheltered, Moderately exposed, Sheltered, Ultra sheltered, Very sheltered, Extremely sheltered, Moderately exposed, Sheltered, Ultra sheltered, Very sheltered
Salinity preferencesFull (30-40 psu), Full (30-40 psu)
Depth range15-1500
Other preferencesNo text entered
Migration PatternNon-migratory / resident

Habitat Information

Absent from the Irish Sea and from the east coast of Britain. Can often be found living on Modiolus sp. or empty scallop shells.

Life history

Adult characteristics

Reproductive typeGonochoristic (dioecious)
Reproductive frequency Annual protracted
Fecundity (number of eggs)No information
Generation timeInsufficient information
Age at maturityData deficient.
SeasonApril - November
Life span5-10 years

Larval characteristics

Larval/propagule type-
Larval/juvenile development Lecithotrophic
Duration of larval stage2-10 days
Larval dispersal potential 100 -1000 m
Larval settlement periodInsufficient information

Life history information

Longevity is suspected to be between 8-10 years. There is no obvious sexual dimorphism although the colour of the gonads may be distinguishing. Testes are light coloured white, pink, cream or blue and ovaries are orange-brown. Egg diameter is 120-125 microns. The species is free-spawning and fertilisation is external in the surrounding water column. The eggs are more dense than seawater and hatch into a free-swimming larval stage. The larvae are fully developed within three days and settle out in no more than a few days. Most of the literature suggests that dispersal ability is not great. Although the species may inhabit areas with water flow rates of up to 3 knots, the often restricted and sheltered habitat such as sea lochs may reduce dispersal ability. The breeding season in western Scotland has been inferred from the presence of recently settled juveniles. The larva may be able to delay settlement if the initial substratum is unsuitable or the water is too deep.

Sensitivity reviewHow is sensitivity assessed?

Physical pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
High Moderate Moderate Low
The adults are permanently cemented to the substratum so substratum loss would result in the death of the population. Adults are permanently attached to the substratum so no adult immigration is possible. No information is available about fecundity. Dispersal ability is not considered to be that great although in many locations there are nearby populations (particularly the west coast of Scotland). Reproduction occurs annually and over an extended period of time.
High Moderate Moderate Moderate
The dorsal valve of the shell can be clamped down and low oxygen concentrations can be tolerated for a few days. However smothering by sediment for a month will prevent feeding and restrict oxygen concentrations for considerably longer and will probably cause death. Adults are permanently attached to the substratum so no adult immigration is possible. No information is available about fecundity. Dispersal ability is not considered to be that great although in many locations there are nearby populations (particularly the west coast of Scotland). Reproduction occurs annually and over an extended period of time.
Low Very high Very Low Moderate
Neocrania anomala has a complex mechanism for removing unwanted particulate material brought in with the inhalant water current. Increases in siltation rate will result in a more regular requirement for this material to be removed. This will have an energetic cost and interfere with feeding. On removal of the factor it may take some time for the animals to regain condition.
No information
Not relevant Not relevant Not relevant Moderate
The species tends to be attached to hard substrata at depths of at least 15 metres. It is extremely unlikely that the population would be exposed to desiccation.
Not relevant Not relevant Not relevant Moderate
The species tends to be attached to hard substrata at depths of at least 15 metres. It is extremely unlikely that the population would be exposed to an emergence regime.
No information
High Moderate Moderate Moderate
The species is found in waters with a maximum velocity of 2-3 knots. Increases above this level would probably cause death. Decreases in water flow rate are unlikely to have any effect as feeding currents are generated by the animal itself. Adults are permanently attached to the substratum so no adult immigration is possible. No information is available about fecundity. Dispersal ability is not considered to be that great although in many locations there are nearby populations (particularly the west coast of Scotland). Reproduction occurs annually and over an extended period of time.
No information
Intermediate High Low
The geographic distribution of Neocrania anomala extends to the north and south of the British Isles and so is exposed to higher and lower water temperatures. Small, long term changes in temperature are unlikely to have much effect. Short acute changes, particularly increases may cause death. Adults are permanently attached to the substratum so no adult immigration to supplement the population is possible. No information is available about fecundity. Dispersal ability is not considered to be that great although in many locations there are nearby populations (particularly the west coast of Scotland). The species may live for up to ten years. Reproduction occurs annually and over an extended period of time.
No information
Tolerant Not relevant Not sensitive Low
The species has no reliance on light availability. It is found at up to 1500 metres in depth where light availability is virtually nil. Changes in light transmission and attenuation are unlikely to affect this species.
No information
High Moderate Moderate Moderate
This species is not very tolerant of wave exposure being generally found in sheltered locations like fjords and sea lochs or in deeper water. Increases in wave exposure above moderately exposed would probably cause death. Adults are permanently attached to the substratum so no adult immigration is possible. No information is available about fecundity. Dispersal ability is not considered to be that great although in many locations there are nearby populations (particularly the west coast of Scotland). Reproduction occurs annually and over an extended period of time.
No information
Low Very high Very Low Low
The species probably has limited facility for detection of noise vibrations. Local noise may cause the animal to close its valves.
Low Very high Very Low Moderate
Although the species does not have eyes or pigment spots, there is a mechanism for visual detection and a highly developed 'shadow reflex' in response to moving objects where the dorsal valve snaps shut. How this is of use in deep water with very low light levels is uncertain. On removal of the factor it may take some time for the animals to regain condition.
Intermediate High Low Moderate
Although the animal is protected by a calcified shell, it is not massively strong and physical disturbance due to a passing scallop dredge will probably cause damage and death. Adults are permanently attached to the substratum so no adult immigration to supplement the population is possible. No information is available about fecundity. Dispersal ability is not considered to be that great although in many locations there are nearby populations (particularly the west coast of Scotland). The species may live for up to ten years. Reproduction occurs annually and over an extended period of time (Long & Stricker, 1991; James et al., 1992).
High Moderate Moderate Moderate
Neocrania anomala is permanently attached to the substratum. If removed, the attachment cannot be reformed. Once detached, the brachiopod can then be moved around by water currents into unsuitable orientations or habitat and will probably cause death. Adults are permanently attached to the substratum so no adult immigration is possible. No information is available about fecundity. Dispersal ability is not considered to be that great although in many locations there are nearby populations (particularly the west coast of Scotland). Reproduction occurs annually and over an extended period of time.

Chemical pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
No information No information No information Not relevant
Insufficient
information
Heavy metal contamination
No information No information No information Not relevant
Insufficient
information
Hydrocarbon contamination
No information No information No information Not relevant
Insufficient
information
Radionuclide contamination
No information No information No information Not relevant
Insufficient
information
Changes in nutrient levels
No information No information No information Not relevant
Insufficient
information
Tolerant Not relevant Not sensitive High
Neocrania anomala is found in a variety of salinity conditions ranging from full down through variable and reduced to low (Connor et al., 1997a.)
No information
Low Very high Very Low High
Brachiopods generally have low metabolic rates with oxygen consumption being about half that of a similar sized bivalve mollusc. They can sustain anaerobic metabolism for 3-5 days. The articulate brachiopod Terebratulina unguicula is found in conditions where oxygen concentrations are frequently below 0.1 mg/l. At low oxygen concentrations activity may be reduced. On removal of the factor it may take some time for the animals to regain condition.

Biological pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
No information No information No information Not relevant
Insufficient
information
No information No information No information Not relevant
Insufficient
information
Not relevant Not relevant Not relevant Low
It is extremely unlikely that this species will be subject to targeted extraction.
Tolerant Not relevant Not sensitive Low
Neocrania anomala has no known obligate relationships.

Additional information

Importance review

Policy/legislation

- no data -

Status

Non-native

Importance information

Novocrania anomala may be a dominant component of species assemblages in which it is found. Novocrania anomala may be preyed upon by starfish, crustacea, gastropods and fish. The shells of brachiopods are easily drilled into, in comparison to molluscs, and the shells of Novocrania anomala are often heavily bored. However, predation levels are apparently low, possibly because of a low energy yield or because it is an unpalatable species.

Bibliography

  1. Atkins, D. & Rudwick, M.J.S., 1962. The lophophore and ciliary feeding mechanisms of the brachiopod Crania anomala (Müller). Journal of the Marine Biological Association of the United Kingdom, 42, 469-480.

  2. Brunton, C.H.C. & Curry, G.B., 1979. British Brachiopods. London: Academic Press. [Synopses of the British Fauna, no. 17.]

  3. Connor, D.W., Dalkin, M.J., Hill, T.O., Holt, R.H.F. & Sanderson, W.G., 1997a. Marine biotope classification for Britain and Ireland. Vol. 2. Sublittoral biotopes. Joint Nature Conservation Committee, Peterborough, JNCC Report no. 230, Version 97.06., Joint Nature Conservation Committee, Peterborough, JNCC Report no. 230, Version 97.06.

  4. Harper, D.A.T., 1991. The brachiopods Neocrania and Terebratulina from Galway Bay. Irish Naturalists' Journal, 23, 371-376.

  5. 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.]

  6. James, M.A., Ansell, A.D., Collins, M.J., Curry, G.B., Peck, L.S. & Rhoda, M.C., 1992. Biology of living brachiopods. Advances in Marine Biology, 28, 175-387.

  7. Long, J.A. & Stricker, S.A., 1991. Brachiopoda. In Reproduction of marine invertebrates, Vol. VI. Echinoderms and Lophophorates. (ed. A.C. Giese, J.S. Pearse & V.B. Pearse). California: The Boxwood Press.

  8. Rowell, A.J., 1960. Some early stages in the development of the brachiopod Crania anomala (Müller). Annals and Magazine of the Natural History Society, 13th Series, 3, 35-52.

  9. Rudwick, M.J.S., 1970. Living and fossil brachiopods. London: Hutchinson University Library

Citation

This review can be cited as:

Jackson, A. 2000. Novocrania anomala A brachiopod. 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/1331

Last Updated: 19/04/2000