Figure 55.13 Interspecific Competition Can Restrict a Species’ Range Interspecific competition with acorn barnacles (Semibalanus) restricts stellate barnacles (Chthamalus) to a smaller portion of the intertidal zone than they could otherwise occupy. Larvae of both species settle throughout the intertidal, but at lower levels acorn barnacles grow much faster and eliminate the stellate barnacle larvae. In the upper reaches of the intertidal, however, the greater susceptibility of acorn barnacles to desiccation (drying out) allows stellate barnacles to outcompete them. The two species can coexist in a small portion of the intertidal zone.