A brachiopod (Novocrania anomala)
Novocrania anomala
Photographer: Keith Hiscock Copyright: Dr Keith Hiscock
Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help
| Researched by | Angus Jackson | Refereed by | This information is not refereed |
| Authority | (O. F. Müller, 1776) | ||
| Other common names | - | Synonyms | Crania anomala (Müller, 1776), Neocrania anomala (Müller, 1776) |
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
15-1500Identifying 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 -
Biology review
Taxonomy
| Phylum | Brachiopoda | Lamp shells |
| Class | Craniata | |
| Order | Craniida | |
| Family | Craniidae | |
| Genus | Novocrania | |
| Authority | (O. F. Müller, 1776) | |
| Recent Synonyms | Crania anomala (Müller, 1776)Neocrania anomala (Müller, 1776) | |
Biology
| Typical abundance | Moderate density | ||
| Male size range | 0.23 - 15mm | ||
| Male size at maturity | |||
| Female size range | Small(1-2cm) | ||
| Female size at maturity | |||
| Growth form | Bivalved | ||
| Growth rate | Data deficient | ||
| Body flexibility | No information | ||
| Mobility | Sessile | ||
| Characteristic feeding method | Active suspension feeder | ||
| Diet/food source | Planktotroph | ||
| Typically feeds on | seston | ||
| Sociability | No information | ||
| Environmental position | Epifaunal | ||
| Dependency | No information found. | ||
| Supports | No 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 preferences | Open coast, Offshore seabed, Sea loch / Sea lough, Open coast, Offshore seabed, Sea loch / Sea lough |
| Biological zone preferences | Lower circalittoral, Lower infralittoral, Upper circalittoral, Lower circalittoral, Lower infralittoral, Upper circalittoral |
| Substratum / habitat preferences | Bedrock, Large to very large boulders, Other species, Small boulders, Bedrock, Large to very large boulders, Other species, Small boulders |
| Tidal strength preferences | Moderately 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 preferences | Extremely sheltered, Moderately exposed, Sheltered, Ultra sheltered, Very sheltered, Extremely sheltered, Moderately exposed, Sheltered, Ultra sheltered, Very sheltered |
| Salinity preferences | Full (30-40 psu), Full (30-40 psu) |
| Depth range | 15-1500 |
| Other preferences | No text entered |
| Migration Pattern | Non-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 type | Gonochoristic (dioecious) | |
| Reproductive frequency | Annual protracted | |
| Fecundity (number of eggs) | No information | |
| Generation time | Insufficient information | |
| Age at maturity | Data deficient. | |
| Season | April - November | |
| Life span | 5-10 years |
Larval characteristics
| Larval/propagule type | - |
| Larval/juvenile development | Lecithotrophic |
| Duration of larval stage | 2-10 days |
| Larval dispersal potential | 100 -1000 m |
| Larval settlement period | Insufficient 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 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 | 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
| Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
| No information | No information | No information | Not relevant | |
| Insufficient information | ||||
| No information | No information | No information | Not relevant | |
| Insufficient information | ||||
| No information | No information | No information | Not relevant | |
| Insufficient information | ||||
| No information | No information | No information | Not relevant | |
| Insufficient information | ||||
| 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
| Intolerance | Recoverability | Sensitivity | Evidence/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
| National (GB) importance | - | Global red list (IUCN) category | - |
Non-native
| Native | - | ||
| Origin | - | Date Arrived | - |
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
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.
Brunton, C.H.C. & Curry, G.B., 1979. British Brachiopods. London: Academic Press. [Synopses of the British Fauna, no. 17.]
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.
Harper, D.A.T., 1991. The brachiopods Neocrania and Terebratulina from Galway Bay. Irish Naturalists' Journal, 23, 371-376.
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.]
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.
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.
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.
Rudwick, M.J.S., 1970. Living and fossil brachiopods. London: Hutchinson University Library
Datasets
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: 2023-01-30
Citation
This review can be cited as:
Last Updated: 19/04/2000
