Phyllidiidae is a family of sea slugs, dorid nudibranchs, marine gastropod mollusks in the superfamily Phyllidioidea.

The mantle of these oval nudibranchs is flattened dorsoventrally and its dorsal surface is covered with hard, colored tubercles.

[1] In contrast with the other nudibranchs from the clade Doridacea, the species in this family lack buccal armature, i. e. radulae and jaws.

The gill leaflets are situated along the ventral area and to the side (= ventrolateral ) instead of consisting of a dorsomedian (= along the middle line of the upper surface) circlet .

However their colors are warning signals indicating special capabilities to deter predators, such as bioactive chemical defense.

As their small mouth lacks a radula and other buccal hard parts, they are known as predators adapted for sucking on sponges.