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UTAS Home > IMAS Home > Image Key > Mollusca >  Pteropod


Blainville 1824


Phylum Mollusca
Class Gastropoda
Subclass Orthogastropoda
Superorder Heterobranchia
Order Opisthobranchia
Suborder Thecosomata


  • Range in size from a few mm to 1 or 2 cm.

Distinguishing characteristics

  • Planktonic opisthobranch molluscs belonging to two Orders:
    • Thecosomata (shelled bodies):
      • Thecosome pteropds have a very thin transparent calcareous shell that can be coiled or triangular.
      • The foot has two very large parapodia or wings, hence the name pteropod or wing-foot. Note that pteropod is not a formal taxonomic term.
      • The wings are used for swimming as well as suspension feeding on microplankton using cilia.
      • Both the shells and body are very delicate and easily damaged, and are rarely caught completely intact.
    • Gymnosomata (naked bodies):
      • Gymnosomes are more robust, lack a shell and the wings are much smaller, appearing as lateral lobes.
      • Gymnosome pteropods are carnivorous.


  • Very common in the open ocean.