Arctica planata was a comparatively large, robust clam living buried in the London Clay seabed. It is interpreted as an infaunal suspension feeder, drawing seawater down to its gills and removing plankton and other suspended organic particles while most of the animal remained protected within the sediment.

Its thick shell would have given useful protection from predators and from movement of the seabed. The species is especially characteristic of parts of the early Eocene succession and could form a conspicuous part of the larger bivalve community alongside smaller clams, pinnids and predatory gastropods.