BIOTIC Species Information for Sagitta spp.
Researched bySean Lindsley-Leake Data supplied byMarLIN
Refereed byThis information is not refereed
Scientific nameSagitta spp. Common nameAn arrow worm
MCS CodeL11 Recent Synonyms

PhylumChaetognatha Subphylum
Superclass ClassSagittoidea
Subclass OrderAphragmophora
SuborderCtinodontina FamilySagittidae
GenusSagitta Species

Additional Information
Taxonomy References
General Biology
Growth form Feeding method
Mobility/MovementPermanent attachment
Environmental position
Typical food types HabitFree living
Bioturbator FlexibilityHigh (>45 degrees)
FragilityFragile SizeSmall-medium(3-10cm)
Height Growth Rate
Adult dispersal potential DependencyIndependent
General Biology Additional InformationChaetognaths are transparent or translucent and are covered by a cuticle. They have fins and a pair of hooked, chitinous, grasping spines on each side of their heads that are used in hunting. The spines are covered with a hood when swimming. They have a distinct head, trunk and tail.
Biology References Russell, 1932, Barnes et al., 2001,
Distribution and Habitat
Distribution in Britain & Ireland
Global distribution
Biogeographic range Depth range
Distribution Additional Information

Substratum preferences Physiographic preferences
Biological zone Wave exposure
Tidal stream strength/Water flow Salinity
Habitat Preferences Additional Information
Distribution References
Reproduction/Life History
Reproductive typeProtandrous hermaphrodite
Developmental mechanismDirect Development
Reproductive SeasonSee additional information Reproductive LocationAs adult
Reproductive frequencySee additional information Regeneration potential No
Life span<1 year Age at reproductive maturity<1 year
Generation time<1 year FecundityInsufficient information
Egg/propagule size0.3mm Fertilization typeInternal
Larval/Juvenile dispersal potential100-1000m Larval settlement periodSee additional information
Duration of larval stage11-30 days   
Reproduction Preferences Additional InformationRussell,(1932) notes that in the Plymouth area Sagitta elegans has 4/5 broods per year, whilst Alvarez-Cadena (1993) notes that in the Irish Sea S.elegans has two generations per year but that this is temperature dependant as Arctic species reproduce every 2 years. Falkenhaug(1993) notes that Sagitta is semelparous in the Barents Sea. Moriyuki (1975) gives the following description of larval development: The body length (from the tip of the head to the base of the tail) of larvae, newly-hatched to 2-days old, ranged from 1.23 to 1.42 mm long in 6 individuals. The larva is provided with a pair of posterior fins, but not yet furnished with the anterior fin: the existence of eye pigments cannot be confirmed for the thick collarette extending nearly all over the body; no hooks are developed yet; the median vertical septum is found already in the posterior portion of the body, though the tail septum is not yet formed. Through the rearing of larvae for 12 days, it was found that seven-day old larvae, 1.47-1.65 mm in length, were mostly provided with the tail septum, but with neither hooks nor eyes, while eight to eleven-day old larvae, 1.69-2.20 mm in length, were furnished with eight hooks on each side, but still without eyes observable on the dorsal surface of the head. Barnes et al (2001) note that chaetognath's developmental mechanism is direct, which contradicts Moriyuki (1975).
Reproduction References Alvarez-Cadena, 1993, Alvarez-Cadena, 1993(b), Falkenhaug, 1993, Russell, 1932, Moriyuki, 1975, Barnes et al., 2001,
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