Anaspidea

gastropod order

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June 18, 2026

Quick Summary

The term "Anaspidea" refers to an order of marine gastropods, commonly known as sea hares. These creatures are characterized by a reduced, flat shell, prominent ear-like tentacles, and a smooth or warty body. Sea hares primarily feed on large seaweeds and are simultaneous hermaphrodites. Research on sea hares has significantly contributed to the scientific understanding of the biochemical basis of learning. Gastropod classification has undergone extensive debate, with traditional anatomical features being challenged by cladistic and molecular studies. The Anaspidea order is part of the subclass Opisthobranchia.12

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gastropod
Classification
Order Anaspidea Shell reduced to flat plate; feed on large seaweed rather than microscopic algae; sea hares (Aplysiidae); 1 other small family. Order Notaspidea Shell and gill usually present; no parapodia (extensions of foot); sperm groove open; shell prominent, reduced, or hidden by mantle; 2 families.…
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Order Anaspidea Shell reduced to flat plate; feed on large seaweed rather than microscopic algae; sea hares (Aplysiidae); 1 other small family. Order Notaspidea Shell and gill usually present; no parapodia (extensions of foot); sperm groove open; shell prominent, reduced, or hidden by mantle; 2 families.…
Read More