Image Key > Annelida > Magelonidae

• Larvae can reach up to 4 mm.

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

• 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).