Rich inshore food resources were vital to the coastal Calusa, who were primarily a fishing people. The mangrove forests, seagrass meadows, and mud flats near the coast provided the energy base for a complex food web as well as nutrition and safe havens for small fishes.

Some scholars have argued that the Calusa became socially complex and politically powerful without recourse to plant and animal husbandry due mainly to their exceptionally bountiful coastal environment. However, more recent research shows that resources were spatially and temporally variable. Based on our accumulated information, we think that changes in settlement, subsistence, technology, and cultural practices were associated significantly with environmental fluctuations. The responses to them reveal a process of learning about and adjusting to an environment that was bountiful during long stretches of time, paltry and unforgiving during others, and possessed of a capacity to devastate with little warning. Calusa adaptations included a belief system that valued the knowledge of the elders and even the deceased; engineering skills that improved living conditions and enhanced cultural connections, and buffering mechanisms that allowed the resilient Calusa to survive, and even to prosper, during periodic episodes of resource deprivation.