MarLIN

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

A colonial sea squirt (Morchellium argus)

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

Summary

Description

Clumps of pink or red lobes each about 4 cm long and consisting of many zooids. Distinguished from other polyclinids especially by the sand coating on the column.

Recorded distribution in Britain and Ireland

Recorded from all around the coasts of Britain and Ireland except parts of the eastern coast of England and parts of the eastern and southern coasts of Ireland. Few records from Shetland.

Global distribution

Known from Britain and Ireland and parts of the French Atlantic coast.

Habitat

Present on the shore mainly on vertical surfaces, under overhangs and in caves. In the sublittoral, often conspicuous amongst foliose algae in the lower infralittoral especially in wave sheltered areas.

Depth range

+1 to -10 m chart datum

Identifying features

  • Colonies of pink or red lobes joined at the base.
  • Each lobe is about 4 cm long with a stalk diameter of about 1 cm.
  • Each lobe has a long firm sand-coated stalk and a wider rounded head.
  • The zooid has eight lobes on the oral siphon and a small pointed atrial languet with four red spots on the base of the oral siphon.

Additional information

No text entered

Listed by

- none -

Further information sources

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Biology review

Taxonomy

PhylumChordata
ClassAscidiacea
OrderAplousobranchia
FamilyPolyclinidae
GenusMorchellium
Authority(Milne-Edwards, 1841)
Recent Synonyms

Biology

Typical abundanceModerate density
Male size range4cm
Male size at maturity
Female size rangeSmall-medium(3-10cm)
Female size at maturity
Growth formCushion
Growth rate
Body flexibility
Mobility
Characteristic feeding methodActive suspension feeder, Non-feeding
Diet/food source
Typically feeds onSuspended organic matter.
Sociability
Environmental positionEpifaunal
DependencyIndependent.
SupportsNone
Is the species harmful?Yes

Moderate levels of toxicity were found against invertebrate larvae by Teo & Ryland (1995).

Biology information

-none-

Habitat preferences

Physiographic preferencesOpen coast, Offshore seabed, Strait / sound, Sea loch / Sea lough, Ria / Voe, Estuary, Enclosed coast / Embayment
Biological zone preferencesLower eulittoral, Lower infralittoral, Sublittoral fringe, Upper infralittoral
Substratum / habitat preferencesBedrock, Large to very large boulders, Small boulders
Tidal strength preferencesModerately Strong 1 to 3 knots (0.5-1.5 m/sec.), Strong 3 to 6 knots (1.5-3 m/sec.), Very Weak (negligible), Weak < 1 knot (<0.5 m/sec.)
Wave exposure preferencesExposed, Extremely sheltered, Moderately exposed, Sheltered, Ultra sheltered, Very sheltered
Salinity preferencesFull (30-40 psu), Variable (18-40 psu)
Depth range+1 to -10 m chart datum
Other preferences
Migration PatternNon-migratory / resident

Habitat Information

No text entered

Life history

Adult characteristics

Reproductive typePermanent (synchronous) hermaphrodite
Reproductive frequency
Fecundity (number of eggs)100-1,000
Generation time<1 year
Age at maturity
SeasonJune - October
Life span1-2 years

Larval characteristics

Larval/propagule type-
Larval/juvenile development Lecithotrophic
Duration of larval stage< 1 day
Larval dispersal potential 100 -1000 m
Larval settlement periodInsufficient information

Life history information

Eggs are about 0.34 mm diameter. Larvae are held in the atrial cavity and have a trunk about 0.8 mm long. The free-swimming period of the larva is about 2-3 hours. Berrill (1950) suggests that brooding colonies are present in September and October but records in the Plymouth Marine Fauna suggest breeding June to September.

Sensitivity reviewHow is sensitivity assessed?

Physical pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
High High Moderate High
Colonies are sessile and will therefore be lost along with their substratum. Larvae disperse in the water column so that, providing coonies survive nearby, recovery will occur following the late summer larval dispersal phase.
High High Moderate Moderate
Colonies rely on being able to pump water for respiration and feeding and cannot extend to any great extent to above layer of smothering sediment. Whilst they may survive for a little time in conditions where they are unable to draw water though the siphons, it is expected that they would be killed by smothering that lasts more than a few days. Larvae disperse in the water column so that, providing colonies survive nearby, recovery will occur following the late summer larval dispersal phase.
Low High Low Moderate
Colonies produce mucous which is shed to remove deposited silt. Colonies live in areas where high suspended sediment levels commonly occur and it is therefore expected that intolerance is low. Larvae disperse in the water column so that, providing colonies survive nearby, recovery will occur following the late summer larval dispersal phase.
No information
High High Moderate Moderate
Colonies are likely to dry and be damaged by exposure to air and especially sunshine in non-damp situations on the shore. Larvae disperse in the water column so that, providing colonies survive nearby, recovery will occur following the late summer larval dispersal phase.
Intermediate High Low Low
Colonies live in the intertidal only in locations where damp conditions prevail (under overhangs and under boulders). In such a situation, there will be some tolerance to increased emersion times but it is likely that colonies will not survive during periods of hot drying weather. Larvae disperse in the water column so that, providing colonies survive nearby, recovery will occur following the late summer larval dispersal phase.
No information
Low High Low Low
Morchellium argus lives in a wide range of flow regimes. Larvae disperse in the water column so that, providing colonies survive nearby, recovery will occur following the late summer larval dispersal phase.
No information
Low Very high Very Low Moderate
Morchellium is in the middle of its geographical range in Britain and Ireland suggesting that it will survive slightly higher and lower temperatures.
Intermediate High Low Moderate
Morchellium is in the middle of its geographical range in Britain and Ireland suggesting that it will survive slightly higher and lower temperatures. Crisp (1964) did not record any specific effects on Morchellium following the severe cold winter of 1962/63 but noted that compound ascidians were slower to recover from winter de-differentiation, or may have been killed in North Wales.
Low High Low Low
Morchellium lives in areas such as the entrances to estuaries where highly turbid conditions occur from time-to-time especially as a result of river run-off. Morchellium does not rely on light penetration and so, although populations seem to be restricted to shallow depths, is unlikely to be affected by changes in light levels.
No information
Low High Low Low
Morchellium lives in a wide range of flow regimes although vigorous wave action may detach colonies. Larvae disperse in the water column so that, providing colonies survive nearby, recovery will occur following the late summer larval dispersal phase.
No information
Tolerant Not relevant Not sensitive High
Tunicates are not known to have organs sensitive to noise.
Tolerant Not relevant Not sensitive High
Tunicates are not known to respond to visual presence.
Intermediate High Low Moderate
Colonies are very flexible and soft providing a buffer against external abrasion from such factors as a fishing pot landing on a colony. Morchellium lives in a wide range of flow regimes although high currents or vigorous wave action may detach colonies. However, individuals and colonies may be scraped off the rock by an anchor or passing dredge. Intolerance is therefore assessed as intermediate. Larvae disperse in the water column so that, providing colonies survive nearby, recovery will occur following the late summer larval dispersal phase.
High High Moderate Moderate
The colonies are attached permanently to the substratum and will not re-attach so that displacement, even if to a suitable habitat, would most likely result in mortality. Morchellium lives in a wide range of flow regimes although high currents or vigorous wave action may detach colonies. Larvae disperse in the water column so that, providing colonies survive nearby, recovery will occur following the late summer larval dispersal phase.

Chemical pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
No information Not relevant No information Not relevant
Heavy metal contamination
No information Not relevant No information Not relevant
Hydrocarbon contamination
No information Not relevant No information Not relevant
Radionuclide contamination
No information Not relevant No information Not relevant
Changes in nutrient levels
Tolerant Not relevant Not sensitive Moderate
Morchellium occurs where nutrient levels are likely to reach high levels (at the entrance to estuaries). The species is dependant on food sources that are not likely to be affected by local nutrient concentrations.
Intermediate High Low Low
Colonies occur in full and variable salinity conditions suggesting significant tolerance to at least lowered salinity. Larvae disperse in the water column so that, providing colonies survive nearby, recovery will occur following the late summer larval dispersal phase.
No information
No information Not relevant No information Not relevant

Biological pressures

 IntoleranceRecoverabilitySensitivityEvidence/Confidence
No information Not relevant No information Not relevant
No information Not relevant No information Not relevant
Intermediate High Low Moderate
Larvae disperse in the water column so that, providing colonies survive nearby, recovery will occur following the late summer larval dispersal phase.
Intermediate High Low
where extraction of other species from under boulder habitats results in the stones being left downside up, there will be significant damage to Morchellium colinies. However, most other forms of extraction of species that co-occur with Morchellium (especially deployment of pots or creels to catch shellfish) are unlikely to cause damage to Morchellium.

Additional information

Importance review

Policy/legislation

- no data -

Status

Non-native

Importance information

-none-

Bibliography

  1. Berrill, N.J., 1950. The Tunicata with an account of the British species. London: Ray Society.

  2. Crisp, D.J. (ed.), 1964. The effects of the severe winter of 1962-63 on marine life in Britain. Journal of Animal Ecology, 33, 165-210.

  3. Crisp, D.J., Southward, A.J. & Southward, E.C., 1981. On the distribution of the intertidal barnacles Chthamalus stellatus, Chthamalus montagui and Euraphia depressa. Journal of the Marine Biological Association of the United Kingdom, 61, 359-380.

  4. 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.]

  5. JNCC (Joint Nature Conservation Committee), 1999. Marine Environment Resource Mapping And Information Database (MERMAID): Marine Nature Conservation Review Survey Database. [on-line] http://www.jncc.gov.uk/mermaid

  6. MBA (Marine Biological Association), 1957. Plymouth Marine Fauna. Plymouth: Marine Biological Association of the United Kingdom.

  7. National Biodiversity Network (NBN) Atlas website. Available from: http://www.nbnatlas.org.  Accessed 01 April 2017

  8. Picton, B.E. & Costello, M.J., 1998. BioMar biotope viewer: a guide to marine habitats, fauna and flora of Britain and Ireland. [CD-ROM] Environmental Sciences Unit, Trinity College, Dublin., http://www.itsligo.ie/biomar/

  9. Teo, S.L.-M. & Ryland, J.S., 1995. Potential antifouling mechanisms using toxic chemicals in some British ascidians. Journal of Experimental Marine Biology and Ecology, 188, 49-62.

Citation

This review can be cited as:

Hiscock, K. 2006. Morchellium argus A colonial sea squirt. 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/1373

Last Updated: 09/11/2006