BIOTIC Species Information for Electra pilosa
|Researched by||Dr Harvey Tyler-Walters||Data supplied by||MarLIN|
|Refereed by||Dr Peter J. Hayward|
|Scientific name||Electra pilosa||Common name||A sea mat|
|MCS Code||Y178||Recent Synonyms||None|
|Additional Information||Colonies of Electra pilosa growing on erect substrata (e.g. a hydroid) may continue to grow lengthways once they have used up the available substratum, forming narrow, bilaminar fronds of zooids side by side, once described as Electra verticillata. Colonies growing on small pieces of substratum (e.g. a shell) occasionally enclose the substratum forming an unattached spherical colony, 3-7cm in diameter (Hayward & Ryland, 1998).|
|Taxonomy References||Howson & Picton, 1997, Hayward & Ryland, 1995b, Hayward & Ryland, 1998, Ryland, 1967, Ryland, 1976, Ryland, 1970,|
|Growth form||Crustose hard
||Feeding method||Active suspension feeder
|Typical food types||Phytoplankton, algal spores.||Habit||Attached|
|Bioturbator||Not relevant||Flexibility||None (< 10 degrees)|
|Height||Growth Rate||Specific growth rate 0.08 / day|
|Adult dispersal potential||10-100m||Dependency||Independent|
|General Biology Additional Information||Growth form
Electra pilosa displays a variety of growth forms, such as, stellate patches on flat substrata, cylindrical growths around algae to narrow tufts, and narrow bilaminar fronds or occasionally as spherical masses around small substrata, described earlier (see Ryland, 1967, 1976; and Silén, 1987 for reviews).
The median proximal spine may become greatly elongated in response to overgrowth by colonies of other bryozoans (Stebbing, 1973; Ryland, 1976) or in response to wave related abrasion by algae (Bayer et al., 1997). The extended spine may protect the feeding polypide from physical or mechanical disturbance (Bayer et al., 1997).
Growth rates in bryozoans have been shown to be vary with environmental conditions, especially water flow, food supply, temperature, competition for food and space, and genotype. For example:
The structure and function of the bryozoan lophophore was reviewed by Ryland (1976), Winston, (1977) and Hayward & Ryland (1998). Best & Thorpe (1994) suggested that intertidal Bryozoa would probably be able to feed on small flagellates, bacteria, algal spores and small pieces of abraded macroalgae.
Electra pilosa and other bryozoans have been reported to cause dermatitis and occupational eczema in fishermen (Ryland, 1967; Jeanmougin et al., 1987 summary only).
|Biology References||Hayward & Ryland, 1995b, Hayward & Ryland, 1998, Ryland, 1967, Jeanmougin et al, 1987, Stebbing, 1973, Ryland, 1976, Bayer et al., 1997, Best & Thorpe, 1986, Bayer et al., 1994, Silén, 1987, Hermansen et al., 2001, Okamura, 1988, Ryland, 1977, Menon, 1972, Hunter & Hughes, 1994, Ryland, 1970, Best & Thorpe, 1994, Winston, 1977,|
|Distribution and Habitat|
|Distribution in Britain & Ireland||Common on all coasts of the British Isles, although under recorded on parts of the east coast.|
|Global distribution||Common in all temperate seas.|
|Biogeographic range||Not researched||Depth range||Intertidal to at least 50m|
|Migratory||Non-migratory / Resident|
|Distribution Additional Information||Electra pilosa may be found on most substrata, and is part of the epiphytic fauna of macroalgae such as %Fucus serratus% in the intertidal and the stipes or holdfasts of laminarians in the subtidal. Electra pilosa may also be found encrusting the shells of shellfish such as mussels. It is also a common member of the fouling community (Ryland, 1967). The abundance of bryozoans is positively correlated with supply of hard substrata and hence with current strength (Eggleston, 1972b; Ryland, 1976). Similarly, the abundance of Electra pilosa increased with increasing fucoid density and surface area (O'Connor et al., 1979).|
Large to very large boulders
Other species (see additional information)
Artificial (e.g. metal/wood/concrete)
|Physiographic preferences||Open coast
Strait / sound
Ria / Voe
Enclosed coast / Embayment
|Biological zone||Mid Eulittoral
|Wave exposure||Moderately Exposed
|Tidal stream strength/Water flow||Strong (3-6 kn)
Moderately Strong (1-3 kn)
Weak (<1 kn)
|Salinity||Full (30-40 psu)
|Habitat Preferences Additional Information|
|Distribution References||Hayward & Ryland, 1995b, Hayward & Ryland, 1998, Bruce et al., 1963, Ryland, 1967, Ryland, 1976, Ryland, 1977, Moore, 1973c, Ryland, 1970, O'Connor et al., 1979, Gontar & Denisenko, 1989,|
|Reproductive Season||August to September||Reproductive Location||Water column|
|Reproductive frequency||Annual episodic||Regeneration potential||No|
|Life span||Insufficient information||Age at reproductive maturity||Insufficient information|
|Generation time||<1 year||Fecundity||Up to ca 30 oocytes|
|Egg/propagule size||121-145 µm||Fertilization type||Internal|
|Reproduction Preferences Additional Information||Reproduction
Bryozoan colonies are hermaphrodite, however, zooids may be monoecious, dioecious, protandrous or protogynous, depending on species (Hayward & Ryland, 1998). Sperm are shed from pores in the polypide tentacles of male zooids (Hayward & Ryland, 1998). In Electra pilosa maternal lophophores may actively collect sperm (Temkin, 1996). The ovaries produce up to 31 oocytes of 121-145 µm in diameter, which are released into the coelomic cavity. Temkin (1996) has shown recently that fertilization is internal, rather than external as thought previously (see Reed, 1991). Eggs come into contact with sperm (either as aggregates or singly) in the coelomic cavity, fertilization occurring at or near ovulation (Temkin, 1996). Embryos are shed into the water column and develop into planktonic cyphonautes larvae (Ryland, 1976; Reed, 1991; Hayward & Ryland, 1998). Entrainment of released sperm by the tentacles of feeding polypides in bryozoans, may reduce dispersal, resulting in self-fertilization (Temkin, 1996).
Individual zooids may produce up to 31 eggs and potentially the same number of embryos (with a fertilization efficiency of 83-100%) (Temkin, 1994), although Hyman (1959) reported a maximum of 17 eggs being released. However, while each individual zooid is not prolific, the fecundity of the colony is probably directly proportional to the number of functional zooids (Bayer et al., 1994).
Colonies containing eggs and sperm are present in August and September and cyphonautes larvae are present in the plankton throughout the year (Hayward & Ryland, 1998). Electra pilosa was reported to settle between April and the end of November, with peaks in May/June and July to August (Ryland, 1967).
Bayer et al. (1994) reported that colonies of Electra pilosa maintained in the laboratory died from the inside out, i.e. after several months the central part of the colony generally began to die. They noted that longevity data for Electra pilosa colonies was not available. However, although Electra pilosa colonies could probably survive for several years, it is probably adapted to ephemeral habitats, capable of rapid growth and reproduction of numerous offspring (r-selected).
Bryozoan larvae are probably sensitive to surface contour, chemistry and the proximity of conspecific colonies. However, Hayward & Ryland (1998) suggested that larval behaviour at settlement is only of prime importance to species occupying ephemeral habitats. For example, Electra pilosa larvae tend to orientate themselves with water flow along Fucus serratus fronds (the trend increasing with wave action) (Ryland, 1977), prefer to settle at the distal ends of the fronds and on the concave surfaces of the seaweed (Seed, 1985). (Eggleston, 1972b) demonstrated that the number and abundance of species of bryozoan increased with increased current strength, primarily due to a resultant increase in the availability of stable, hard substrata (Eggleston, 1972b; Ryland, 1976). Ryland (1976) reported that significant settlement in bryozoans was only found near a reservoir of breeding colonies. Ryland (1977) suggested that marine bryozoan larvae tend to settle on the underside of submerged structures or in shaded habitats, possibly due to avoidance of accumulated sediment or competition from algae. However, Electra pilosa larvae have an extended planktonic life and this species is a common member of fouling communities, and occurs on buoys where many other species of bryozoa are unable to colonize (Ryland, 1967). Therefore, Electra pilosa probably exhibits good dispersal and potentially very rapid recruitment.
|Reproduction References||Hayward & Ryland, 1998, Ryland, 1967, Ryland, 1976, Bayer et al., 1994, Ryland, 1977, Nielsen, 1990, Reed, 1991, Seed, 1985, Ryland, 1970,|