Sea Slugs and Allies
Whilst this group also includes most land snails, the majority of Euthyneuran gastropods found in the marine environment are sea slugs, with a greatly reduced, internal, or absent shell. However, they also include the false limpets and air-breathing (pulmonate) marine snails.
Headshield (Cephalaspid) Slugs
Nudibranchs
Side-gilled (Pleurobranch) Slugs
Runcinidan Slugs
Sacoglossan Slugs
False Limpets (Order Siphonariida)
Umbrella Slugs (Order Umbraculida)