Females are highly territorial and protective of their feeding space, which consists of a thin layer of microalgae on the rocky substrate (Stimson 1970, Shanks 2002). When partially or fully submerged in seawater, females actively patrol their grazing territory (or ‘garden’) by ‘bulldozing off’ non-territorial males, juveniles and interspecific intruders (for example, other mobile gastropods) with the anterior portion of their shells (Stimson 1970, Shanks 2002). They also prevent the encroachment of sessile species such as mussels, anemones, macroalgae and barnacles (Stimson 1970).
Males of this species, as well as some small females, generally reside outside of the territory of a dominant female or within areas difficult for the larger females to reach (for example, cracks in the substrate or on mussel shells).
Juveniles and small males are often found grazing on the shells of the mussel, Mytilus californianus.
Oftentimes, older and larger L. gigantea individuals will have encrusting animals such as barnacles and algae growing on the backside of their shell. In addition, mobile gastropods such as other limpet species and chitons will use an L. gigantea shell as grazing space.
Besides humans, the only other known predator of L. gigantea is the Black Oystercatcher, Haematopus bachmani.