BIOTIC

BIOTIC Species Information for Electra pilosa

Researched by

Dr Harvey Tyler-Walters

Data supplied by

MarLIN

Refereed by

Dr Peter J. Hayward

Taxonomy

Scientific name

Electra pilosa

Common name

A sea mat

MCS Code

Y178

Recent Synonyms

None

Phylum

Bryozoa

Subphylum

Superclass

Class

Gymnolaemata

Subclass

Order

Cheilostomatida

Suborder

Malacostegina

Family

Electridae

Genus

Electra

Species

pilosa

Subspecies

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,

General Biology

Growth form

Crustose hard

Feeding method

Active suspension feeder

Mobility/Movement

Permanent attachment

Environmental position

Epifaunal
Epilithic
Epiphytic
Epizoic
Epibenthic

Typical food types

Phytoplankton, algal spores.

Habit

Attached

Bioturbator

Not relevant

Flexibility

None (< 10 degrees)

Fragility

Fragile

Size

Small-medium(3-10cm)

Height

Growth Rate

Specific growth rate 0.08 / day

Adult dispersal potential

10-100m

Dependency

Independent

Sociability

Colonial

Toxic/Poisonous?

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
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:

Best & Thorpe (1986) reported that feeding rate increased with increasing food concentration;
Bayer et al. (1994) noted that variation in growth rates between colonies due to genotype was greater than that due to food ration;
Okamura (1988) reported that in epiphytic communities, feeding rate increased with increasing flow (from 0.01-0.02 m/sec to 0.1-0.12m/s) but was reduced by competing bryozoan communities (Alcyonidium sp. or Flustrellidra hispida) in slow flow but enhanced by them in fast flow conditions; and
bryozoans studied (inc. Electra pilosa) in natural currents in the Menai Strait, fed adequately and maintained growth even in very high current flows (Hermansen, et al., 2001).
Although growth rates increased with temperature, zooid size decreased, which may be due to increased metabolic costs at higher temperature (Menon, 1972; Ryland, 1976; Hunter & Hughes, 1994). In the Menai Straits larger zooids are produced in spring at times of peak phytoplankton primary productivity but mean zooid size decreased as temperatures increased in summer (Okamura, 1987 cited in Hunter & Hughes, 1994).

Growth rates of 0.1-0.12 µ /day were reported, irrespective of flow regime, and genotype, while natural population were reported to grow at ca 0.08 µ/ day (Hermansen et al., 2001).

Feeding
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.

Allergenic response
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).

Substratum preferences

Bedrock
Large to very large boulders
Small boulders
Cobbles
Algae
Other species (see additional information)
Artificial (e.g. metal/wood/concrete)
Seagrass
Under boulders
Caves
Overhangs

Physiographic preferences

Open coast
Strait / sound
Sealoch
Ria / Voe
Estuary
Enclosed coast / Embayment

Biological zone

Mid Eulittoral
Lower Eulittoral
Sublittoral Fringe
Upper Infralittoral
Lower Infralittoral

Wave exposure

Moderately Exposed
Sheltered

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,

Reproduction/Life History

Reproductive type

Budding
Permanent hermaphrodite

Developmental mechanism

Planktotrophic

Reproductive Season

August to September

Reproductive Location

Water column

Reproductive frequency

Annual episodic

Regeneration potential

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

Larvae/Juveniles
Larval/Juvenile dispersal potential	>10km	Larval settlement period
Duration of larval stage	See additional information

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).
Fecundity
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).

Reproductive season
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).
Longevity
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).

Recruitment
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,