Pomatoceros triqueter

Researched ByLizzie TylerData Supplied ByUniversity of Sheffield
Refereed byThis information is not refereed.
Taxonomy
Scientific namePomatoceros triqueterCommon nameKeelworm
MCS CodeP1341Recent SynonymsNone
PhylumAnnelidaSubphylum
SuperclassClassPolychaeta
SubclassOrderSabellida
SuborderFamilySerpulidae
GenusPomatocerosSpeciestriqueter
Subspecies  
Additional Information
  • May be confused with Pomatoceros lamarcki, the tube of which differs from Pomatoceros triqueter as it has two vestigial ridges, one on each side, in addition to the median keel. Further differences can only be seen when the worm is removed from its tube (Hayward & Ryland, 1995). Further distinction between the two species can be obtained by using biochemical genetics, as described by Ekaratne et al. (1982).
  • Males are cream in colour whilst females are bright pink/orange in colour (Thomas, 1940).
Taxonomy References Hayward & Ryland, 1995b, Howson & Picton, 1997, Hayward et al., 1996, Fish & Fish, 1996, Thomas, 1940, Ekaratne et al., 1982
General Biology
Growth formVermiform segmented, TubicolousFeeding methodPassive suspension feeder, Active suspension feeder
Mobility/MovementPermanent attachmentEnvironmental positionEpibenthic, Epifaunal, Epilithic
Typical food typesPlankton and detritusHabitSee additional information
BioturbatorFlexibilityHigh (>45 degrees)
FragilityFragileSizeSmall(1-2cm)
HeightGrowth Rate1.5 mm/month
Adult dispersal potentialNoneDependencyIndependent
SociabilitySolitary
Toxic/Poisonous?No
Additional InformationGrowth
  • Once settled onto the substratum the worm forms a temporary delicate semi-transparent tube, which, when calcareous material is later added at the anterior end (Hayward & Ryland, 1995) dissolves over time (Dons, 1927). The tube is formed by a secretion of calcium carbonate (obtained from sea water) from the collar (Thomas, 1940).
  • Growth rate is usually measured by the increase in length of the tube over a period of time. Dons (1927) found that the youngest sessile stages of the animals in Trondheim occurred when the tubes were 800-1200µm long and the animal was approximately 500µ in length.
  • Hayward & Ryland (1995) and Dons (1927) stated that growth is rapid and sexual maturity is reached in approximately 4 months. Growth rate has been observed by Dons (1927) to be 1.5 mm per month, although this varied with external conditions. Males and females exhibit the same growth rate (Castric-Fey, 1983). Animals settling during spring show the best growth rate and the rate is greatest during the first year (Castric-Fey, 1983).
  • Castric-Fey (1983) reported that the number of segments of the worm increases with age, with a linear relationship being present within the first 6 months.
Feeding & Respiration
Thomas (1940) reviewed feeding and respiration in the polychaete. Pomatoceros triqueter never leaves its tube. Occasionally the posterior end of the tube becomes blocked by a calcareous plate with holes in. Respiration and excretion take place using cilia action to set up currents, bringing water in and down the length of the tube and flushing it back out the same way. Respiration occurs through the surface of the body and the branchial crown.

Feeding takes place by spreading apart its branchial filaments to expose a central groove. Using cilia action, it induces a current and transports food particles towards it mouth. If particles are too large or too numerous, the tip of a filament bends over and removes it. No sorting of food particles takes place.

Biology References Hayward & Ryland, 1995b, Dons, 1927, Thomas, 1940, Castric-Fey, 1983
Distribution and Habitat
Distribution in Britain & IrelandCommon and widespread on all coasts.
Global distributionOccurs from the coasts of north west Europe to the Mediterranean.
Biogeographic rangeNot researchedDepth range
MigratoryNon-migratory / Resident
Distribution Additional Information
  • Segrove (1941) studied Pomatoceros triqueter in south England and found that there are usually ten times as many males as females present.
  • The species has been noted to occur in very exposed to extremely sheltered wave action, very sheltered to exposed water flow rate, and in areas where there is little or no silt present (Price et al., 1980).
  • Pomatoceros triqueter is considered to be a primary fouling organism (Crisp, 1965), colonizing artificial commercially important structures such as buoys, ships hulls, docks and offshore oil rigs (OECD, 1967).
  • Pomatoceros triqueter is an opportunistic species, making use of available space quickly. In Bantry Bay, south-west Ireland, fouling by the tube worm caused a 65% mortality of scallops and prevented scallops from recolonizing the area after spat collection (Burnell et al., 1991). They also reported that mussel farmers considered that most inner areas of the bay would be subject to this type of fouling.
  • Rubin (1985) reported that Pomatoceros triqueter overgrew colonies of encrusting Bryozoa to become the dominant species on experimental panels. However, Bryozoa then grew on the tubes of the species, thereby avoiding exclusion.
  • Dominance of %Pomatoceros lamarckii% over Pomatoceros triqueter is dependent on climatic conditions (Castric-Fey, 1983).
    • Substratum preferencesBedrock, Large to very large boulders, Small bouldersPhysiographic preferencesOpen coast, Enclosed coast / Embayment
    Biological zoneSublittoral Fringe, Upper Infralittoral, Lower Infralittoral, Upper CircalittoralWave exposureVery Exposed, Exposed, Moderately Exposed, Sheltered, Very Sheltered, Extremely Sheltered
    Tidal stream strength/Water flowStrong (3-6 kn), Moderately Strong (1-3 kn), Weak (<1 kn), Very Weak (negligible)SalinityFull (30-40 psu)
    Habitat Additional Information
    AMBI Group (Borja et al., 2000)II 
    Distribution References Hayward & Ryland, 1995b, Hayward et al., 1996, Fish & Fish, 1996, Castric-Fey, 1983, Segrove, 1941, Bacescu, 1972, Price et al., 1980, Crisp, 1965, OECD, 1967, Burnell et al., 1991, Rubin, 1985, Hayward & Ryland, 1995b
    Reproduction/Life History
    Reproductive typeProtandrous hermaphrodite Developmental mechanismPlanktotrophic
    Reproductive SeasonSee additional informationReproductive LocationInsufficient information
    Reproductive frequencyAnnual episodic Regeneration potentialNo
    Life span2-3 yearsAge at reproductive maturity<1 year
    Generation timeInsufficient informationFecundity
    Egg/propagule sizeFertilization typeInsufficient information
    Larvae/Juveniles
    Larval/Juvenile dispersal potential>10kmLarval settlement periodSee additional information
    Duration of larval stage11-30 days  
    Additional Information
    • Male Pomatoceros triqueter release spermatogonia or primary spermatocytes and females release primary oocytes through a pair of gonoducts, consisting of a ciliated funnel and tube (Thomas, 1940).
    • Hayward & Ryland (1995) and Segrove (1941) suggested that breeding of Pomatoceros triqueter probably takes place throughout the year. However, Hayward & Ryland (1995) noted a breeding peak in spring and summer and records from Port Erin by Moore (1937) indicated that breeding only took place in April in this location.
    • Castric-Fey (1983) studied variations in settlement rate and concluded that, although the species settled all year round, very rare settlement was observed during winter and maximum settlement occurred in April, June, August and Sept-Oct. Studies in Bantry Bay (Cotter et al., 2003) revealed a single peak in recruitment during summer (especially July and August) with very little recruitment at other times of the year. More individuals settled on panels at 7 m than at 4 m.
    • Larvae are pelagic for about 2-3 weeks in the summer. However, in the winter this amount of time increases to about 2 months (Hayward & Ryland, 1995).
    Longevity
    Longevity has been recorded to be between 1.5 to 4 years. Hayward & Ryland (1995) noted that individuals lived approximately 1.5 years, with most individuals dying after breeding (Hayward & Ryland, 1995). Castric-Fey (1983) found that under laboratory conditions, individuals were still alive after 2.5 years. However, Castric-Fey (1983) also stated that under natural conditions it is probable that they do not live any longer than this. Whilst Dons (1927) found that, according to measured growth rate, some of the individuals he studied would have been at least 4 years old.
    Reproduction References Hayward & Ryland, 1995b, Dons, 1927, Thomas, 1940, Castric-Fey, 1983, Segrove, 1941, Moore, 1937, Cotter et al., 2003