Reticulopodia, the diagnostic cytoplasmic appendage of the foraminifera, are complex networks of branched and anastomosed pseudopodia. The instantaneous patterns of these networks are highly variable and are remodeled almost continuously. Real-time light microscopic observations demonstrate that these morphogenetic processes occur autonomously throughout the entire networks, even at their farthest reaches which may be located at great distances from the cell body. Portions of reticulopodia severed from the cell body undergo autonomous and stereotyped morphological rearrangements to form satellites, which are a relatively large cytoplasmic mass located centrally within a radiating pseudopodial network. Pseudopodial movements and structural rearrangements are active energy-requiring processes that depend on intracellular factors such as the formation and reorganization of microtubule cytoskeletal elements. Here we show that that reticulopodia consistently assume a spiral shape when placed on a cationic substrate, indicating that the pseudopodial pattern is also influenced by environmental factors such as interactions with the substratum. Our studies suggest that reticulopodia are self-organizing, and that their instantaneous reticular form is an emergent property continuously recalculated from real-time processing of myriad physiological and environmental imputs. Reticulopodial form at any point or region appears to be the summed behavioral response to these parameters. Our studies indicate that reticulopodial morphology and behavior can be modified by environmental stimuli, like substratum adhesivity, and suggest that processes, such as shell patterning, that depend on pseudopodia could also be modified by environmental factors.

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