Arachnactidae is a family of tube-dwelling anemones in the order Ceriantharia.

It is the only family in the monotypic order Penicillaria and comprises around 38 species.

They differ from other ceriantharians in the makeup of their cnidome (the types of cnidocyte present), the relative sizes of the oral discs and the shape and structure of the mesenteries.

[1] The World Register of Marine Species includes the following genera in the family :[2]

This class Anthozoa related article is a stub.