The brittlestar – Amphiura filiformis.
Photograph by Judith Oakley (http://www.marlin.ac.uk/species/detail/1400).
Amphiura filiformis is a benthic brittlestar species, discovered by O. F. Müller in 1776. It is an infaunal Echinoderm, belonging to the class Ophiuroidea, which inhabits sandy and muddy sediments in the North Sea and North Atlantic ocean. A.filiformis feeds on plankton through active and passive suspension feeding, and detritus through deposit feeding. Varying in size annually, this species tends to reach its maximum size in August when it reaches sexual maturity.
A.filiformis has an important benthic ecological role, due to its species-sediment and interspecies interactions. It has evolved many physiological, morphological and behavioural adaptations for life in the benthos, and is a sign of a healthy benthic community according to its stage three classification in the Pearson-Rosenberg model of succession.
A recent university assessment required the creation of a group video presentation on the ecological role of a benthic species.
Ecological role – Elin Thomas:
“Amphiura filiformis has an important ecological role since it provides a link between the benthic and pelagic environments, especially in the North Sea where there are large populations of the species. It also provides an insight into benthic succession. Solan et al. (2004) found that A.filiformis has a disproportionately strong impact on bioturbation in Galway Bay since it is large, highly mobile, and consistently one of the most abundant species in the area. Therefore, the effect of extinction on bioturbation largely depends on whether A.filiformis survives the event or not. Wood et al. (2009) described how A.filiformis plays a key role in sediment nutrient cycling by irrigating and mixing the sediment. They demonstrated that as A.filiformis activity increased, the sediment release of nitrate and uptake of phosphate also increased. It has also been observed that A.filiformis populations have been increasing in abundance in the North Sea. This is thought to be due to eutrophication increasing the food supply and the decline in flatfish predator populations due to overfishing. As well as A.fililformis affecting the environment, the physical arrangement of the environment also influences the species. For example, A.filiformis responds to the tidal cycle by feeding at mid-tide when the current speed makes feeding most efficient.”
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