BIOTIC Species Information for Amphiura filiformis
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Researched byLizzie Tyler Data supplied byUniversity of Sheffield
Refereed byThis information is not refereed.
Scientific nameAmphiura filiformis Common nameA brittlestar
MCS CodeZB154 Recent SynonymsNone

PhylumEchinodermata SubphylumAsterozoa
Superclass ClassOphiuroidea
Subclass OrderOphiurida
Suborder FamilyAmphiuridae
GenusAmphiura Speciesfiliformis

Additional InformationNo text entered
Taxonomy References Howson & Picton, 1997, Hayward & Ryland, 1995b, Hayward et al., 1996, Mortensen, 1927,
General Biology
Growth formRadial
Feeding methodPassive suspension feeder
Active suspension feeder
Surface deposit feeder
Sub-surface deposit feeder
Environmental positionInfaunal
Typical food typesPlankton and detritus. HabitFree living
Bioturbator FlexibilityHigh (>45 degrees)
FragilityFragile SizeMedium(11-20 cm)
HeightInsufficient information Growth Rate0.20-1.67% body weight per day
Adult dispersal potential1km-10km DependencyIndependent
General Biology Additional Information
  • Typical abundance: High density populations (i.e. higher than an arbitrary figure of 150/m²) of Amphiura filiformis are common in the north east Atlantic Ocean and occur in sediments having silt/clay levels of about 10 to 20%. For example, in Galway Bay, Ireland, populations studied over an 8 year period had a maximum of 904 individuals per m² (O'Connor et al., 1983). Low density populations also occur along the north west European coastline.
  • Size: Sizes at maturity given are from a population of Amphiura filiformis studied in Galway Bay, Ireland (O'Connor et al., 1983). Sköld et al. (2001) reported similar sizes. The disc diameter of Amphiura filiformis shows annual increases and decreases associated with sexual maturity. Maximum size is attained in August, just prior to gamete release and is followed by a decrease in mean size (O'Connor et al., 1983).
  • Growth rate: Muus (1981) reported that newly settled recruits have a disc diameter of 0.3 mm and that they take 2 years to reach a size of 1.3 mm. However, Sköld et al. (2001) suggested that after 2 years, a disk size of ca 4 mm (concomitant with adult size and hence sexual maturity) could be attained. Josefson (1995) estimates the main part of disc growth occurs within the first 5 to 7 years of life. Sköld et al. (2001) studied post-larval recruits in the Gullmarsfjord and reported an asymptotic sigmoidal growth pattern for Amphiura filiformis (when growth data for adults and juveniles were combined). Specific growth rates of the post-larval settlers was 0.42% per day (disk diameter) and 1.76% per day (mean arm length) Sköld et al. (2001). Somatic and germinal growth rates may be enhanced by, for example, nutrient enrichment (Sköld & Gunnarsson, 1996) or temperature (see sensitivity section).
  • Feeding method: Amphiura filiformis feed on suspended material in flowing water, but will change to deposit feeding in stagnant water or areas of very low water flow (Ockelmann & Muus, 1978). Suspension feeding capability is attained after about one year, at which point juveniles experienced exponential growth rates ( Sköld et al., 2001).
Biology References Loo et al., 1996, Muus, 1981, O'Connor et al., 1983, Ockelmann & Muus, 1978, Josefson, 1995, Sköld et al., 2001, Hayward & Ryland, 1990, Julie Bremner, unpub data,
Distribution and Habitat
Distribution in Britain & IrelandMost British and Irish coasts although records have not been found for the south east of England.
Global distributionWestern Norway to the Mediterranean.
Biogeographic rangeNot researched Depth range5 - 1200 m
MigratoryNon-migratory / Resident   
Distribution Additional InformationPossible density dependent migration where migration occurs on or in the sediment. Burrowing through the sediment takes longer but the risk of predation is decreased.

Substratum preferencesMuddy sand
Sandy mud
Physiographic preferencesOffshore seabed
Enclosed coast / Embayment
Biological zoneSublittoral Fringe
Upper Infralittoral
Lower Infralittoral
Upper Circalittoral
Lower Circalittoral
Wave exposureSheltered
Very Sheltered
Extremely Sheltered
Tidal stream strength/Water flowModerately Strong (1-3 kn)
Weak (<1 kn)
Very Weak (negligible)
SalinityFull (30-40 psu)
Habitat Preferences Additional Information
Distribution References Hayward & Ryland, 1995b, Hayward et al., 1996, Hayward & Ryland, 1990, Julie Bremner, unpub data, Gerdes, 1977, Mortensen, 1927,
Reproduction/Life History
Reproductive typeGonochoristic
Developmental mechanismPlanktotrophic
Reproductive SeasonSummer Reproductive LocationAs adult
Reproductive frequencyAnnual protracted Regeneration potential No
Life span11-20 years Age at reproductive maturity3-5 years
Generation timeInsufficient information Fecundity50000
Egg/propagule size Fertilization typeExternal
Larval/Juvenile dispersal potential>10km Larval settlement periodSee additional information
Duration of larval stage1-6 months   
Reproduction Preferences Additional Information
  • Life span
    Muus (1981) estimates the life span of the species to be 25 years based on oral width (which does not change with gonadial growth) to determine the stability of population structure, with recruitment taking place at the 0.3mm size levels. In very long term studies of Amphiura filiformis populations in Galway Bay O'Connor et al. (1983) indicate a life span of some 20 years is possible. Sköld et al. (1994) also estimated a similar life span for the species in the Skagerrak, west Sweden. However, early suggestions for the life span of Amphiura filiformis had been estimated at between 2 and 6 years (Buchanan, 1964; O'Conner & McGrath, 1980; Ocklemann & Muus, 1978). These early estimates of the life span of ophiuroids were based on several factors which have been found to give a possible margin for error (Muus, 1981). Firstly, disc diameter had traditionally been used as the basis for population structure determination. However, this introduces a margin of error because gonadial growth causes disc diameter to increase during the breeding season and decrease after spawning. Secondly, most estimates were based on recruitment of individuals at a disc size of around 1mm so that sieving on a 1mm mesh did not retain the earliest settlers which were smaller.
  • Fecundity
    A total of 50,000 oocytes per ripe female is reported by O'Connor (pers. comm. in Duineveld et al., 1987).
  • Gametes
    Time of first and last gametes recorded is from Galway Bay, Ireland (Bowmer, 1982). A discrete, relatively short annual breeding period (Jun-Sep) was observed with peak activity in August. In the same area O'Conner & McGrath (1980) observed that all large animals spawned during August/September in two consecutive years. Buchanan (1964) reported that Amphiura filiformis breeds in July in Britain. In the Ligurian Sea in the Mediterranean the spawning period is much longer, lasting from March to November (Pedrotti, 1993).
  • Recruitment
    Descriptions of the life history of Amphiura filiformis vary greatly in the literature. In most of these studies, the basis for determining the size of recruits, and therefore periods of recruitment, growth rates and lifespan, has been the mesh size used during sampling operations. The most commonly used mesh size, 1mm, has therefore not sampled the earliest settlers. For example, in a study of Amphiura filiformis populations in Galway Bay over a period of 2 years O'Conner & McGrath (1980) were not able to identify discrete periods of recruitment. However, other studies suggest autumn recruitment (Buchanan, 1964) and spring and autumn (Glémarec, 1979). Using a 265µm mesh size Muus (1981) identified a peak settlement period in the autumn with a maximum of 6800 recruits per m². Sköld et al. (2001) reported settling densities of 7,100 - 7,400 per m² in October in the Gullmarsfjord. Muus (1981) shows the mortality of these settlers to be extremely high with less than 5% contributing to the adult population in any given year. In Galway Bay populations, small individuals make up ca. 5% of the population in any given month, which also suggests the actual level of input into the adult population is extremely low (O'Connor et al., 1983).
  • Dispersal potential
    After cold winter related mass mortality of Amphiura filiformis in the German Bight, Gerdes (1977) calculated that dispersal to a location 10km away was within the reach of the larvae. However, dispersal is largely determined by water movements and currents. The species is thought to have a long pelagic life. Sköld et al. (1994) estimated the time lag between full gonads and settlement to be 88 days. This duration is comparable to the time period when pelagic larvae have been recorded in the plankton from July to November in one study and August to December in another (Sköld et al., 1994).
Reproduction References O'Connor & McGrath, 1980, Bowmer, 1982, Pedrotti, 1993, Muus, 1981, Gerdes, 1977, Glémarec, 1979, O'Connor et al., 1983, Ockelmann & Muus, 1978, Buchanan, 1964, Sköld, 1994, Duineveld et al., 1987, Sköld et al., 2001, Eckert, 2003, Julie Bremner, unpub data,
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