Fig. 6. Frontal view of a representative pseudopod that formed away from an aggregation stream and was retracted. Time is in seconds (sec). See legend to Fig. 1B for color code. This pseudopod, which formed between 0 and 16 seconds (phase one), maintained the same approximate volume between 16 and 28 seconds (phase two) and retracted between 36 and 60 seconds (phase three). Note the interactions between filopodia and substratum. a, b, c, pseudopodia.