BIOTIC

BIOTIC Species Information for Amphiura filiformis
All Taxonomy Biology Distribution Reproduction

Researched by	Lizzie Tyler	Data supplied by	University of Sheffield
Refereed by	This information is not refereed.
General Biology
Growth form	Radial Stellate	Feeding method	Passive suspension feeder Active suspension feeder Surface deposit feeder Sub-surface deposit feeder
Mobility/Movement	Crawler Burrower	Environmental position	Infaunal
Typical food types	Plankton and detritus.	Habit	Free living
Bioturbator		Flexibility	High (>45 degrees)
Fragility	Fragile	Size	Medium(11-20 cm)
Height	Insufficient information	Growth Rate	0.20-1.67% body weight per day
Adult dispersal potential	1km-10km	Dependency	Independent
Sociability	Gregarious
Toxic/Poisonous?	No
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,