BIOTIC

BIOTIC Species Information for Sagitta spp.

Researched by

Sean Lindsley-Leake

Data supplied by

MarLIN

Refereed by

This information is not refereed

Taxonomy

Scientific name

Sagitta spp.

Common name

An arrow worm

MCS Code

L11

Recent Synonyms

Phylum

Chaetognatha

Subphylum

Superclass

Class

Sagittoidea

Subclass

Order

Aphragmophora

Suborder

Ctinodontina

Family

Sagittidae

Genus

Sagitta

Species

Subspecies

Additional Information

Taxonomy References

General Biology

Growth form

Feeding method

Mobility/Movement

Permanent attachment

Environmental position

Typical food types

Habit

Free living

Bioturbator

Flexibility

High (>45 degrees)

Fragility

Fragile

Size

Small-medium(3-10cm)

Height

Growth Rate

Adult dispersal potential

Dependency

Independent

Sociability

Solitary

Toxic/Poisonous?

Yes

General Biology Additional Information

Chaetognaths 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

Migratory

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 type

Protandrous hermaphrodite

Developmental mechanism

Direct Development
Planktotrophic

Reproductive Season

See additional information

Reproductive Location

As adult

Reproductive frequency

See additional information

Regeneration potential

Life span

<1 year

Age at reproductive maturity

<1 year

Generation time

<1 year

Fecundity

Insufficient information

Egg/propagule size

0.3mm

Fertilization type

Internal

Larvae/Juveniles
Larval/Juvenile dispersal potential	100-1000m	Larval settlement period	See additional information
Duration of larval stage	11-30 days

Reproduction Preferences Additional Information

Russell,(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,