On the swimming of Dictyostelium amoebae

The conventional mode for amoeboid locomotion is crawling. Barry and Bretscher (1) recently showed that Dictyostelium amoebae are also capable of swimming to chemoattractants. They hypothesized that the mechanism for swimming is intimately related to crawling. When crawling, the cell front bifurcates, and protrusions move backward, relative to the cell. The authors (1) conjecture that floating cells executing these same motions will swim. In this letter, we show that, indeed, the shape changes of a crawling cell are sufficient for swimming.