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Trees- ShrubsTwin Fan Worm ( Bispira volutacornis )
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There are 7 species within the genus of Bispira and none of them have been evaluated on the IUCN Redlist (1) (2). The Spiral fan worm is a colonial sedentary fan worm. It has two C-shaped pale-white crowns with usually less than 200 radioles. It can be identified by the composite eyes which are scattered on the outside of the tentacles. The tube of the fan worm is made up of a silt-mucoid outer layer and usually has either a green, purple or brown colouration (3).
If approached by a predator, or if the current flow exceeds 8.7cm s-1, the fan of B. volutacornis retracts into the tube (3) (4). The tube provides protection from predatory fish and crustaceans, as well as having a role in irrigation and respiration.
B. volutacornis is a dioecious polychaeta. It is possible to determine genders of the younger generation based on the colour. The dorsal aspect on the male at maturity is a cream colour, while the females are pink (5). The annual reproductive cycle of 12 months shows that oocyte and sperm maturation is extraovarian. Spawning has been noted to occur during late July and September. It is a polytelic species which survives spawning and releases gametes in a single batch (5).
B. volutacornis is found from the littoral to the sublittoral zone and is commonly found within large numbers on and under rock surfaces and crevices (5).
The geographical range of Bispira volutacornis is more limited than originally thought and is commonly found along the western coasts of Europe.
Studies have shown that the feeding apparatus of Bispira volutacornis is similar to that of other sabellids. Feeding seems to occur between current speeds of 1cm s-1 to 3cm s-1 (4).
Not evaluated under the IUCN Redlist (1).
Description written by Kathryn Woodward (2009)
(1) IUCN, 2009. IUCN. [Online] (2009.1) Available at: www.iucnredlist.org [Accessed 16 June 2009].
(2) Zip Code Zoo, 2009. Bispira volutacornis. [Online] Available at: http://zipcodezoo.com/Animals/P/Paracentrotus_gaimardi/ [Accessed 15 June 2009].
(3) Gregory, P., 2008. Twin-fan worm – Bispira volutacornis. [Online] [Accessed 11 August 2009].
(4) Nash, R. & Keegan, B.F., 2003. Aspects of the feeding biology of the fanworm Bispira volutacornis (Polychaeta: Sabellidae). Journal of the Marine Biological Association of the UK, 3(83), pp.453-56.
(5) Nash, R. & Keegen, B.F., 2003. Reproductive cycle of Bispira volutacornis (Polychaeta: Sabellidae) on the west coast of Ireland. Marine Biology, 143, pp.919-25.
