BIOTIC Species Information for Nemertesia ramosa
Researched byAngus Jackson Data supplied byMarLIN
Refereed byDr Rob Hughes
Reproduction/Life History
Reproductive typeVegetative
Developmental mechanismLecithotrophic
Reproductive SeasonFebruary - September Reproductive LocationAs adult
Reproductive frequencySemelparous Regeneration potential No
Life span<1 year Age at reproductive maturityInsufficient information
Generation time<1 year FecundityInsufficient information
Egg/propagule sizeInsufficient information Fertilization typeInternal
Larval/Juvenile dispersal potential10-100m Larval settlement periodInsufficient information
Duration of larval stage<1 day   
Reproduction Preferences Additional InformationVery little information is directly available on Nemertesia ramosa. Completion of most of the fields has been done through extrapolation from the very similar species Nemertesia antennina from Hughes (1977).
  • Males and females are separate but similar, differentiation being possible through the colour of the reproductive tissues, females being orange (yolk) and males white.
  • Allocation of reproductive frequency is difficult. An individual colony will only reproduce once during its 4-5 month lifespan but this reproductive effort is probably spread over an extended period rather than a short episode. In Nemertesia ramosa, gonothecae have been observed in all months of the year with the exception of January, October, November and December (Ansín Agíl et al., 2001).
  • Information on fecundity is sparse and has only been recorded for Nemertesia antennina as mean length of reproductive areas in relation to total length. Recorded values are only an estimate.
  • The planula larvae are released from the gonothecae and drop off the end of the hydrocladium. They settle and metamorphose at between 12-24 hours. This is the only mobile stage in the life cycle of Nemertesia antennina and therefore very important for dispersal.
  • Dispersal distance is dependent on current speed, turbulence and the height at which the larvae are released but in Torbay, the distance is thought to be between 5 and 50m.
  • The dense larva reduces sinking rates by producing a mucous thread (without the thread the larvae sink at 5mm per second in still water).
  • Once the larva lands on the seabed, further dispersal is limited to crawling although this probably last for no more than 1-2 hours. Crawling speeds may reach up to 5mm per minute on smooth surfaces so the planula larvae will probably not move further than 1-2 m before settlement.
  • Some regeneration may occur from broken stems but this is generally found in few individuals.
Reproduction References Hughes, 1977, Gili & Hughes, 1995, Gili & Hughes, 1995, Ansín Agís et al., 2001,
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