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Fauchald 1977


Phylum Annelida
Class Polychaeta
Subclass Palpata
Order Canalipalpata
Suborder Spionida
Family Magelonidae


  • Larvae can reach up to 4 mm.


  • Common benthic surface-feeders that live as burrowers in sand and mud (as adults).

Distinguishing characteristics

  • Long and slender body.
  • Prominent dorso-ventrally flattened spatulate prostomium.
  • Two long ventrolateral palps.
  • Palps have rows of adhesive papillae rather than a ciliated groove.
  • Each papilla only has 2 cells (unlike adult); one has a single sensory cilium.
  • Long larval chaetae.
  • Asymmetrical larval tentacles.
  • No eye.


  • Widely distributed throughout the world.
  • Larvae of Spionidae are generally the most common developmental stages of polychaete found in plankton samples.


  • Benthic sessile or semi-sessile.
  • Deposit or suspension feeders.
  • Various types of development:
    • pure broadcast spawning
    • planktotrophic and/or lecithotrophic larvae (brooding in capsules or cocoons).
  • Periods of development can be long lasting and can result in large numbers of larvae in coastal areas.
  • Locomotion: Lecithotrophic larvae are weak swimmers. Planktotrophic larvae are strong swimmers (performed by propulsion by the cilia).