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Animal profile

Arrow Worm

Sagitta elegans

SagittoideaOpen-water plankton of cool temperate and subarctic seas

Field profile

Sagitta elegans is a small transparent chaetognath that hangs motionless in the water column and darts at prey. Its head bears rows of grasping spines. Arrow worms are abundant zooplankton predators and are used as indicators of water-mass origin.

Scope note

This is an editorial profile, not a diagnostic field-identification guide or a substitute for current conservation assessments. Follow the cited sources on each fact for the evidence trail.

Published field notes

2025-07-02

Arrow Worm

Arrow worms are used to identify ocean water masses

Because chaetognath species tolerate narrow ranges of temperature and salinity and drift with the water they occupy, oceanographers use their presence in plankton samples as a marker of where a body of water came from.

Read with evidence →

Arrow Worm | Daily Animal Facts