Figure 4. Model of gliding, walking and swimming.

All cells extend pseudopods at a frequency of ∼4 per minute. In gliding cells, pseudopods are large and all contribute to forward moving; side bumps are rare. In walking cells, pseudopods are smaller and only ∼75% of pseudopods contribute to forward movement; these pseudopods convert to side-bumps that are stationary relative to the substrate. In swimming cells, pseudopods are small and convert to side-bumps that move to the rear of the cell. On average walking and swimming cells have ∼3 side-bumps (see table S1)