Behavioral researchers using Amblypygi have noted the regularity at which species engage in agonistic interactions. Despite this, why agonistic interactions occur and how they are resolved is unknown. I conducted paired interactions of the amblypygid Phrynus longipes in Puerto Rico to understand the dynamics of agonistic interactions. Through a series of analyses, I found that agonistic interactions are territory contests common across the demographic range of the species. Further, I decoded the strategy that opponents use to negotiate contests, and used resource contests to explain the peculiar pattern of cannibalism that this species exhibits. I used these results to identify the variation in contests and other behavioral phenotypes across cave and surface populations. This research broadens theory of resource contest evolution and behavioral variation by investigating phenomena in a non-model study system.