Bornellidae is a family of nudibranchs, shell-less marine gastropod molluscs or sea slugs, in the superfamily Dendronotoidea.
Nudibranch species within the Bornellidae family have elongated bodies, with pairs of cerata-like dorsal and lateral appendages, with finger-like branches, running along the length of the body. Each of these appendages has an attached cluster of gills. Their rounded head has a tentacle on either side of the mouth, with tiny finger-like papillae. The rhinophores on the head resemble the dorsal appendages.
Nudibranchs within this family are believed to feed exclusively on hydroids.
The following genus is recognised in the family Bornellidae:
Once placed inside this family, molecular phylogenetic analyses now recover the genus Pseudobornella as a member of Dendronotidae.