Response: habitat compartmentation and envitonmental correlates of food chain length.

25, 27, and 40), three of which appear incomplete, followed by relatively complete aquatic habitats with longer chains. For the two-dimensional webs, seven out of eight webs are incomplete (terrestrial habitats, marshes, and the rocky intertidal). We suggest that the three-dimensional food web descriptions, particularly those of webs in open seas, more completely reflect real food webs, while the two-dimensional and terrestrial three-dimensional webs are descriptions of habitat compartments of real food webs. This is consistent with the resource compartmentation hypothesis and niche theory (6, 8) and the notion of mobile predators linking habitat compartments (9). This analysis also illustrates that relations between environment and chain length cannot be established until the parameters that are