Image Key > Annelida > Spionidae

• Variable.

• Known as ‘palp worms’.
• Selective deposit feeders.

• Two prominent grooved palps to locate prey.
• Palps are generally grooved, ciliated and posses sensory structures.
• Nuchal organs form posterior projections.
• Specialised chaetae.
• Ciliary tufts and bands.

• Widely distributed throughout the world.
• Larvae of Spionidae are generally the most common developmental stages of polychaetes 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).