BIOTIC Species Information for Palmaria palmata
Researched byJacqueline Hill Data supplied byMarLIN
Refereed byDr Thomas Wiedemann
Scientific namePalmaria palmata Common nameDulse
MCS CodeZM170 Recent SynonymsNone/85

PhylumRhodophycota Subphylum
Superclass ClassRhodophyceae
SubclassFlorideophycidae OrderPalmariales
Suborder FamilyPalmariaceae
GenusPalmaria Speciespalmata

Additional InformationSometimes the blade divisions are wedge-shaped and finely dissected above or the blade has numerous linear divisions throughout. This phenomenon seems to occur under fairly sheltered, silty conditions. Such plants are difficult to identify without examining the anatomical structure and the cortical cells in surface view, and have been confused with Callophyllis cristata (L. ex Turn.) Kütz. and Gracilaria foliifera (Forsk.) Børk (Irvine, 1983). Palmaria palmata has a multiaxial, pseudoparenchymatous construction and, in section, can be seen to consist of a large-celled medulla bounded on each side by a small-celled cortex.
Taxonomy References Irvine, 1983, Hayward et al., 1996,
General Biology
Growth formCrustose soft
Feeding methodPhotoautotroph
Mobility/Movement Environmental positionEpilithic
Typical food typesNot relevant HabitAttached
BioturbatorNot relevant FlexibilityHigh (>45 degrees)
FragilityIntermediate SizeLarge(>50cm)
HeightUp to 1m Growth Rate100 % body wt/week
Adult dispersal potentialNone DependencyIndependent
General Biology Additional Information
  • The life-cycle of Palmaria palmata is diplohaplontic and strongly heteromorphic, with a reduced crustose female gametophyte and a macroscopic foliose male gametophyte.
  • Where competition for space and light restricts the occurance of Palmaria palmata on rock the species often has an epiphytic habit on other algae, especially kelps.
Biology References Irvine, 1983, Guiry & Blunden, 1991, Hoek van den et al., 1995, Morgan & Simpson, 1981, Meer van der & Todd, 1980,
Distribution and Habitat
Distribution in Britain & IrelandGenerally distributed throughout Britain and Ireland, but apparently absent from significant stretches of coast in eastern England.
Global distributionArctic Russia to Portugal; Baltic. Artic Canada to USA (New Jersey); USA (Alaska to California); Japan, Korea.
Biogeographic rangeNot researched Depth rangeTo a depth of 20m
MigratoryNon-migratory / Resident   
Distribution Additional InformationNo text entered

Substratum preferencesBedrock
Large to very large boulders
Physiographic preferencesOpen coast
Strait / sound
Enclosed coast / Embayment
Biological zoneSublittoral Fringe
Lower Eulittoral
Upper Infralittoral
Wave exposureModerately Exposed
Tidal stream strength/Water flowStrong (3-6 kn)
Moderately Strong (1-3 kn)
Weak (<1 kn)
SalinityFull (30-40 psu)
Habitat Preferences Additional Information
Distribution References Irvine, 1983, Hardy & Guiry, 2003,
Reproduction/Life History
Reproductive typeGonochoristic
Developmental mechanismSpores (sexual / asexual)
Reproductive SeasonInsufficient information Reproductive LocationAs adult
Reproductive frequencyAnnual episodic Regeneration potential No
Life spanInsufficient information Age at reproductive maturity<1 year
Generation timeInsufficient information FecundityInsufficient information
Egg/propagule sizeInsufficient information Fertilization typeExternal
Larval/Juvenile dispersal potential<10m Larval settlement periodNot relevant
Duration of larval stageNot relevant   
Reproduction Preferences Additional Information
  • Life span: Palmaria palmata is a perennial species with new growth every year. Therefore, the holdfast could remain for several years..
The unusual life cycle of Palmaria palmata is diplohaplontic and strongly heteromorphic, with a reduced female gametophyte, a macroscopic male gametophyte and a foliose tetrasporophyte. The foliose plants seen on the shore and in the shallow subtidal are generally tetrasporophytes and scarcer male gametophytes.
  • The female is a small crust-like plant, in which the carpogonia are borne directly by the vegetative cells.
  • The male gametophyte, on the other hand, is blade-like and produces spermatia that can fertilize the carpogonia of the female crusts.
  • After fertilization the carpogonium does not produce carpospores but instead develops into a blade-like tetrasporophyte.
  • When young, the tetrasporophyte grows attached to the female gametophyte, later its own basal system develops and completely overgrows the tiny female thallus.
  • The adult foliose tetrasporophyte, which is diploid, produces tetraspores meiotically and these in turn develop into crust-like female gametophytes and foliose male gametophytes.
  • Male plants became fertile within 9-12 months. Females need only a few days to become sexually mature.
  • Dispersal distances are short. Females do not release carpospores so male gametophytes release spermatia that then sink rapidly so that male and female gametes can come into contact for fertilization.
Reproduction References Hoek van den et al., 1995,
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