Sealoch anemone (Protanthea simplex)

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Summary

Description

A small delicate sea anemone, usually found with outstretched tentacles. The column of the anemone reaches lengths of up to 2 cm. There are numerous translucent tentacles up to 1.5 cm long, which may span 7 cm. The column of the anemone may be salmon pink with the tentacles a little paler or white, especially near the tips. Deep orange-pink gonads may be visible through the column wall when ripe.

Recorded distribution in Britain and Ireland

From the northern Firth of Clyde all along the west coast of Scotland, particularly in sea lochs. Not recorded in Orkney or Shetland. Recently (June 2006) found in Killary Harbour, Connemara.

Global distribution

Killary Harbour (Connermara, Galway), Western Scotland out to Rockall Bank, round the coasts of the Skagerrak and northern Kattegat, Norway.

Habitat

Occurs characteristically on deep rock in sea lochs, particularly on vertical walls in landward basins. Often found growing on rock or on other species such as tube worms. Otherwise recorded in deep waters down to at least 500 m.

Depth range

9 -500 m deep

Identifying features

  • A small delicate sea anemone up to 2 cm high.
  • Column is smooth and broader distally (1.5 cm) than proximally (1 cm).
  • 100-160 tentacles arranged in 5 or 6 cycles.
  • Inner tentacles up to 1.5 cm, outer tentacles shorter.
  • There is no sphincter.
  • Eight perfect mesenteries present.

Additional information

No text entered

Listed by

- none -

Further information sources

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Biology review

Taxonomy

LevelScientific nameCommon name
PhylumCnidaria
ClassAnthozoa
OrderActiniaria
FamilyGonactiniidae
GenusProtanthea
AuthorityCarlgren, 1891
Recent Synonyms

Biology

ParameterData
Typical abundanceModerate density
Male size rangeUp to 2cm
Male size at maturity
Female size rangeSmall(1-2cm)
Female size at maturity
Growth formCylindrical
Growth rateData deficient
Body flexibility
Mobility
Characteristic feeding methodNon-feeding, Passive suspension feeder
Diet/food source
Typically feeds onData deficient
Sociability
Environmental positionEpifaunal
DependencyNo information found.
SupportsNo information
Is the species harmful?Data deficient

Biology information

This species exhibits an unusual collapse behaviour, where at intervals, muscle tone is rapidly lost and the animals hangs limply from its disk attachment. This is considered to be an egestion process rather than a feeding, alarm or escape response. Despite the primitive musculature, Protanthea simplex is capable of active movement.
In Sweden Protanthea simplex has been recorded historically at densities of up to 2000 per square metre. Svane & Gröndal (1988) reported that the species was abundant below the algal belt in semi-sheltered and sheltered sites in the Gullmarsfjorden, Sweden (10.7 % and 4.5 % cover per 0.25 square metre respectively). This contrasted with earlier work by Gislén, undertaken between 1926-29, where the species was not recorded in the semi-sheltered sites and only made up a small proportion of the total wet weight of species in the sheltered sites (Svane & Gröndal, 1988).

Habitat preferences

ParameterData
Physiographic preferencesOffshore seabed, Strait or Sound, Sea loch or Sea lough
Biological zone preferencesLower circalittoral, Lower infralittoral, Upper circalittoral
Substratum / habitat preferencesBedrock, Biogenic reef, Large to very large boulders, Small boulders
Tidal strength preferencesVery weak (negligible), Weak < 1 knot (<0.5 m/sec.)
Wave exposure preferencesExtremely sheltered, Sheltered, Ultra sheltered, Very sheltered
Salinity preferencesFull (30-40 psu), Variable (18-40 psu)
Depth range9 -500 m deep
Other preferencesNo text entered
Migration PatternNon-migratory or resident

Habitat Information

No text entered

Life history

Adult characteristics

ParameterData
Reproductive typeGonochoristic (dioecious)
Reproductive frequency Annual episodic
Fecundity (number of eggs)No information
Generation timeInsufficient information
Age at maturityInsufficient information
SeasonSeptember - October
Life spanInsufficient information

Larval characteristics

ParameterData
Larval/propagule type-
Larval/juvenile development Oviparous
Duration of larval stage11-30 days
Larval dispersal potential Greater than 10 km
Larval settlement periodInsufficient information

Life history information

At 10-12 °C the larvae spend 15-20 days in the plankton before settling. In Sweden breeding occurs in September and October. Breeding terminates earlier in shallower water. Fertilization of the eggs occurs in the water column. The reproductive organs are white or orange- pink. Fragments of tissue in this species (except the tentacles) are capable of regenerating into complete anemones, a form of vegetative, asexual reproduction (Manuel, 1988).
Apart from Protanthea simplex, the only other species in the family Gonactinidae is Gonactinia prolifera. Gonactinia prolifera is unique in that the planula larva carries 'collar cells' similar in structure to the choanocyes of sponges and it is possible that Protanthea simplex has similar cells (I. Svane, pers. comm.). These secretory cells contain yolk granules and are undoubtedly involved in the formation of the fibrous coating of the planula which is again a unique feature of its planula (Chia et al, 1989).

Sensitivity reviewHow is sensitivity assessed?

Physical pressures

Use / to open/close text displayed

 IntoleranceRecoverabilitySensitivityEvidence / Confidence
Substratum loss [Show more]

Substratum loss

Benchmark. All of the substratum occupied by the species or biotope under consideration is removed. A single event is assumed for sensitivity assessment. Once the activity or event has stopped (or between regular events) suitable substratum remains or is deposited. Species or community recovery assumes that the substratum within the habitat preferences of the original species or community is present. Further details

Evidence

The species is attached to the substratum so substratum loss will mean loss of the population. Although capable of active movement, this is not over long distances making adult immigration highly unlikely. No information is available about growth rate, longevity or fecundity. Larvae remain in the plankton for up to three weeks and so potentially have considerable dispersal potential.
High Moderate Moderate High
Smothering [Show more]

Smothering

Benchmark. All of the population of a species or an area of a biotope is smothered by sediment to a depth of 5 cm above the substratum for one month. Impermeable materials, such as concrete, oil, or tar, are likely to have a greater effect. Further details.

Evidence

The species is delicate and soft bodied. Smothering with 5 cm of sediment is likely to cause physical damage to the anemone as well as restricting respiration and preventing feeding. Although capable of active movement, this is not over long distances making adult immigration highly unlikely. No information is available about growth rate, longevity or fecundity. Larvae remain in the plankton for up to three weeks and so potentially have considerable dispersal potential.
High Moderate Moderate Low
Increase in suspended sediment [Show more]

Increase in suspended sediment

Benchmark. An arbitrary short-term, acute change in background suspended sediment concentration e.g., a change of 100 mg/l for one month. The resultant light attenuation effects are addressed under turbidity, and the effects of rapid settling out of suspended sediment are addressed under smothering. Further details

Evidence

Increased siltation may clog the anemone's tentacles and interfere with feeding. Clearing the sediment will require increased energetic expenditure. Loss of condition may result. It may take a few weeks or months for condition to be regained once energy expenditure returns to normal.
Low Very high Very Low Low
Decrease in suspended sediment [Show more]

Decrease in suspended sediment

Benchmark. An arbitrary short-term, acute change in background suspended sediment concentration e.g., a change of 100 mg/l for one month. The resultant light attenuation effects are addressed under turbidity, and the effects of rapid settling out of suspended sediment are addressed under smothering. Further details

Evidence

 No information
Desiccation [Show more]

Desiccation

  1. A normally subtidal, demersal or pelagic species including intertidal migratory or under-boulder species is continuously exposed to air and sunshine for one hour.
  2. A normally intertidal species or community is exposed to a change in desiccation equivalent to a change in position of one vertical biological zone on the shore, e.g., from upper eulittoral to the mid eulittoral or from sublittoral fringe to lower eulittoral for a period of one year. Further details.

Evidence

The anemone is small and soft bodied, existing entirely sub-tidally. On removal from the water the animals turn into shapeless blobs of tissue. Exposure to desiccating influences is highly likely to cause death. Although capable of active movement, this is not over long distances making adult immigration highly unlikely. No information is available about growth rate, longevity or fecundity. Larvae remain in the plankton for up to three weeks and so potentially have considerable dispersal potential.
High Moderate Moderate Low
Increase in emergence regime [Show more]

Increase in emergence regime

Benchmark. A one hour change in the time covered or not covered by the sea for a period of one year. Further details

Evidence

The anemone is small and soft bodied, existing entirely sub-tidally. On removal from the water the animals turn into shapeless blobs of jelly. Emergence is highly likely to cause death. Although capable of active movement, this is not over long distances making adult immigration highly unlikely. No information is available about growth rate, longevity or fecundity. Larvae remain in the plankton for up to three weeks and so potentially have considerable dispersal potential.
High Moderate Moderate Low
Decrease in emergence regime [Show more]

Decrease in emergence regime

Benchmark. A one hour change in the time covered or not covered by the sea for a period of one year. Further details

Evidence

 No information
Increase in water flow rate [Show more]

Increase in water flow rate

A change of two categories in water flow rate (view glossary) for 1 year, for example, from moderately strong (1-3 knots) to very weak (negligible). Further details

Evidence

Decreases in water flow are unlikely to have any effect but increases in flow rate above weak may prevent the animals from maintaining posture and interfere with feeding. Increased flow rates may also sweep individuals off the substratum. Although capable of active movement, this is not over long distances making adult immigration highly unlikely. No information is available about growth rate, longevity or fecundity. Larvae remain in the plankton for up to three weeks and so potentially have considerable dispersal potential. No information is available about asexual reproduction.
Intermediate High Low Low
Decrease in water flow rate [Show more]

Decrease in water flow rate

A change of two categories in water flow rate (view glossary) for 1 year, for example, from moderately strong (1-3 knots) to very weak (negligible). Further details

Evidence

 No information
Increase in temperature [Show more]

Increase in temperature

  1. A short-term, acute change in temperature; e.g., a 5°C change in the temperature range for three consecutive days. This definition includes ‘short-term’ thermal discharges.
  2. A long-term, chronic change in temperature; e.g. a 2°C change in the temperature range for a year. This definition includes ‘long term’ thermal discharges.

For intertidal species or communities, the range of temperatures includes the air temperature regime for that species or community. Further details

Evidence

No information is available about the temperature preferences of Protanthea simplex. However, the species reaches its southern-most geographical distribution in coastal waters on the west coast of Scotland. Long-term chronic increases in temperature may cause the distribution range of shallow water populations to retreat northwards. Although capable of active movement, this is not over long distances making adult immigration highly unlikely. No information is available about growth rate, longevity or fecundity. Larvae remain in the plankton for up to three weeks and so potentially have considerable dispersal potential.
High Moderate Moderate Very low
Decrease in temperature [Show more]

Decrease in temperature

  1. A short-term, acute change in temperature; e.g., a 5°C change in the temperature range for three consecutive days. This definition includes ‘short-term’ thermal discharges.
  2. A long-term, chronic change in temperature; e.g. a 2°C change in the temperature range for a year. This definition includes ‘long term’ thermal discharges.

For intertidal species or communities, the range of temperatures includes the air temperature regime for that species or community. Further details

Evidence

 No information
Increase in turbidity [Show more]

Increase in turbidity

  1. A short-term, acute change; e.g., two categories of the water clarity scale (see glossary) for one month, such as from medium to extreme turbidity.
  2. A long-term, chronic change; e.g., one category of the water clarity scale (see glossary) for one year, such as from low to medium turbidity. Further details

Evidence

The species probably has very poor facility for visual perception and has no great requirement for light. The species may be found as deep as 400 m where light availability is very limited. Changes in light attenuation are not likely to have any effect.
Tolerant Not relevant Not sensitive Low
Decrease in turbidity [Show more]

Decrease in turbidity

  1. A short-term, acute change; e.g., two categories of the water clarity scale (see glossary) for one month, such as from medium to extreme turbidity.
  2. A long-term, chronic change; e.g., one category of the water clarity scale (see glossary) for one year, such as from low to medium turbidity. Further details

Evidence

 No information
Increase in wave exposure [Show more]

Increase in wave exposure

A change of two ranks on the wave exposure scale (view glossary) e.g., from Exposed to Extremely exposed for a period of one year. Further details

Evidence

The species typically inhabits sheltered waters so decreases in wave exposure are unlikely to have any effect. Increases above moderately exposed are likely to cause damage to the species, as well as interfering with posture and feeding. Deep water populations are unlikely to be affected by changes in wave exposure.
High Moderate Moderate Low
Decrease in wave exposure [Show more]

Decrease in wave exposure

A change of two ranks on the wave exposure scale (view glossary) e.g., from Exposed to Extremely exposed for a period of one year. Further details

Evidence

 No information
Noise [Show more]

Noise

  1. Underwater noise levels e.g., the regular passing of a 30-metre trawler at 100 metres or a working cutter-suction transfer dredge at 100 metres for one month during important feeding or breeding periods.
  2. Atmospheric noise levels e.g., the regular passing of a Boeing 737 passenger jet 300 metres overhead for one month during important feeding or breeding periods. Further details

Evidence

Protanthea simplex probably has limited facility for detection of noise vibrations. It is unlikely to be sensitive to noise.
Tolerant Not relevant Not sensitive Very low
Visual presence [Show more]

Visual presence

Benchmark. The continuous presence for one month of moving objects not naturally found in the marine environment (e.g., boats, machinery, and humans) within the visual envelope of the species or community under consideration. Further details

Evidence

Protanthea simplex probably has limited facility for visual perception. It is unlikely to be sensitive to visual disturbance.
Tolerant Not relevant Not sensitive High
Abrasion & physical disturbance [Show more]

Abrasion & physical disturbance

Benchmark. Force equivalent to a standard scallop dredge landing on or being dragged across the organism. A single event is assumed for assessment. This factor includes mechanical interference, crushing, physical blows against, or rubbing and erosion of the organism or habitat of interest. Where trampling is relevant, the evidence and trampling intensity will be reported in the rationale. Further details.

Evidence

The anemone is delicate and soft bodied. Abrasion is highly likely to cause death. Although capable of active movement, this is not over long distances making adult immigration highly unlikely. No information is available about growth rate, longevity or fecundity. Larvae remain in the plankton for up to three weeks and so potentially have considerable dispersal potential.
High Moderate Moderate Low
Displacement [Show more]

Displacement

Benchmark. Removal of the organism from the substratum and displacement from its original position onto a suitable substratum. A single event is assumed for assessment. Further details

Evidence

Protanthea simplex only forms a temporary attachment with the substratum and is capable of active movement. Displacement may cause inconvenience for the animals and possibly slight damage to the body but is not likely to cause death. It may take a few weeks or months for regeneration and repair of damage to occur.
Low Very high Very Low Low

Chemical pressures

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 IntoleranceRecoverabilitySensitivityEvidence / Confidence
Synthetic compound contamination [Show more]

Synthetic compound contamination

Sensitivity is assessed against the available evidence for the effects of contaminants on the species (or closely related species at low confidence) or community of interest. For example:

  • evidence of mass mortality of a population of the species or community of interest (either short or long term) in response to a contaminant will be ranked as high sensitivity;
  • evidence of reduced abundance, or extent of a population of the species or community of interest (either short or long term) in response to a contaminant will be ranked as intermediate sensitivity;
  • evidence of sub-lethal effects or reduced reproductive potential of a population of the species or community of interest will be assessed as low sensitivity.

The evidence used is stated in the rationale. Where the assessment can be based on a known activity then this is stated. The tolerance to contaminants of species of interest will be included in the rationale when available; together with relevant supporting material. Further details.

Evidence

Insufficient
information
No information No information No information Not relevant
Heavy metal contamination [Show more]

Heavy metal contamination

Evidence

Insufficient
information
No information No information No information Not relevant
Hydrocarbon contamination [Show more]

Hydrocarbon contamination

Evidence

Insufficient
information
No information No information No information Not relevant
Radionuclide contamination [Show more]

Radionuclide contamination

Evidence

Insufficient
information
No information No information No information Not relevant
Changes in nutrient levels [Show more]

Changes in nutrient levels

Evidence

Insufficient
information
No information No information No information Not relevant
Increase in salinity [Show more]

Increase in salinity

  1. A short-term, acute change; e.g., a change of two categories from the MNCR salinity scale for one week (view glossary) such as from full to reduced.
  2. A long-term, chronic change; e.g., a change of one category from the MNCR salinity scale for one year (view glossary) such as from reduced to low. Further details.

Evidence

The species probably only inhabits fully saline waters but this is not certain. Longer term decreases in salinity may cause some of the population to die. Although capable of active movement, this is not over long distances making adult immigration highly unlikely. No information is available about growth rate, longevity or fecundity. Larvae remain in the plankton for up to three weeks and so potentially have considerable dispersal potential. No information is available about asexual reproduction.
Intermediate High Low Low
Decrease in salinity [Show more]

Decrease in salinity

  1. A short-term, acute change; e.g., a change of two categories from the MNCR salinity scale for one week (view glossary) such as from full to reduced.
  2. A long-term, chronic change; e.g., a change of one category from the MNCR salinity scale for one year (view glossary) such as from reduced to low. Further details.

Evidence

 No information
Changes in oxygenation [Show more]

Changes in oxygenation

Benchmark.  Exposure to a dissolved oxygen concentration of 2 mg/l for one week. Further details.

Evidence

Cole et al. (1999) suggest possible adverse effects on marine species below 4 mg/l and probable adverse effects below 2mg/l. There is no information about Protanthea simplex tolerance to changes in oxygenation. Although capable of active movement, this is not over long distances making adult immigration highly unlikely. No information is available about growth rate, longevity or fecundity. Larvae remain in the plankton for up to three weeks and so potentially have considerable dispersal potential.
Intermediate High Low Very low

Biological pressures

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 IntoleranceRecoverabilitySensitivityEvidence / Confidence
Introduction of microbial pathogens/parasites [Show more]

Introduction of microbial pathogens/parasites

Benchmark. Sensitivity can only be assessed relative to a known, named disease, likely to cause partial loss of a species population or community. Further details.

Evidence

Insufficient
information
No information No information No information Not relevant
Introduction of non-native species [Show more]

Introduction of non-native species

Sensitivity assessed against the likely effect of the introduction of alien or non-native species in Britain or Ireland. Further details.

Evidence

Insufficient
information
No information No information No information Not relevant
Extraction of this species [Show more]

Extraction of this species

Benchmark. Extraction removes 50% of the species or community from the area under consideration. Sensitivity will be assessed as 'intermediate'. The habitat remains intact or recovers rapidly. Any effects of the extraction process on the habitat itself are addressed under other factors, e.g. displacement, abrasion and physical disturbance, and substratum loss. Further details.

Evidence

It is extremely unlikely that this species would be subject to extraction.
Not relevant Not relevant Not relevant Low
Extraction of other species [Show more]

Extraction of other species

Benchmark. A species that is a required host or prey for the species under consideration (and assuming that no alternative host exists) or a keystone species in a biotope is removed. Any effects of the extraction process on the habitat itself are addressed under other factors, e.g. displacement, abrasion and physical disturbance, and substratum loss. Further details.

Evidence

Some individual Protanthea simplex use other species such as Ascidia sp., Serpula sp., and Chaetopterus sp. as substrata. Removal of these species may also mean incidental removal of the anemone. It is unlikely that available habitat will be greatly reduced as Protanthea simplex also inhabits rock. Although capable of active movement, this is not over long distances making adult immigration highly unlikely. No information is available about growth rate, longevity or fecundity. Larvae remain in the plankton for up to three weeks and so potentially have considerable dispersal potential.
Intermediate High Low Moderate

Additional information

Importance review

Policy/legislation

- no data -

Status

Non-native

ParameterData
Native-
Origin-
Date ArrivedNot relevant

Importance information

-none-

Bibliography

  1. Carlgren, O., 1893. Studien uber nordische Actinien. Kungliga Svenska Vetenskaps-Akademiens Handlingar, 25, 148pp.

  2. Carlgren, O., 1921. Actiniaria. Pt. 1. Danish Ingolf Expedition, Vol. V, No. 9., pp. 31.  Copenhagen: Bianco Luno.

  3. Carlgren, O., 1949. A survey of the Ptychodactiaria, Corallimorpharia and Actiniaria. Kungliga Svenska Vetenskapsakadamiens Handlingar, Series 4, 1, 16-110.

  4. Chia, F-S., Lützen, J. & Svane, I., 1989. Sexual reproduction and larval morphology of the primitive anthozoan Gonactinia prolifera M. Sars. Journal of Experimental Marine Biology and Ecology, 127, 13-24.

  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. Manuel, R.L., 1988. British Anthozoa. Synopses of the British Fauna (New Series) (ed. D.M. Kermack & R.S.K. Barnes). The Linnean Society of London [Synopses of the British Fauna No. 18.]. DOI https://doi.org/10.1002/iroh.19810660505

  7. McFarlane, I.D., 1985. Collapse behaviour in the primitive sea anemone Protanthea simplex. Marine Behaviour and Physiology, 11, 259-269.

  8. Nyholm, K-G., 1959. On the development of the primitive actinian Protanthea simplex, Carlgren. Zoologiska Bidrag Fran Uppsala, Band 33 1958-1962, 69-78.

  9. Svane, I. & Dolmer, P., 1995. Perception of light at settlement: a comparative study of two invertebrate larvae, a scyphozoan planula and a simple ascidian tadpole. Journal of Experimental Marine Biology and Ecology, 187, 51-61.

  10. Svane, I. & Groendahl, F., 1988. Epibioses of Gullmarsfjorden: an underwater stereophotographical transect analysis in comparison with the investigations of Gislen in 1926-29. Ophelia, 28, 95-110.

Datasets

  1. NBN (National Biodiversity Network) Atlas. Available from: https://www.nbnatlas.org.

  2. OBIS (Ocean Biodiversity Information System),  2025. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2025-05-25

Citation

This review can be cited as:

Jackson, A. 2008. Protanthea simplex Sealoch anemone. In Tyler-Walters H. and Hiscock K. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 25-05-2025]. Available from: https://www.marlin.ac.uk/species/detail/1345

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Last Updated: 24/04/2008