Animal cells move. Even in a complex multicellular organism such as a human, many cells are on the move all the time. During development, for example, cells produced in one region of the embryo crawl to other locations before settling down and specializing.

How do celled organisms move?

Unicellular organisms achieve locomotion using cilia and flagella. By creating currents in the surrounding environment, cilia and flagella can move the cell in one direction or another. Unicellular organisms generally live in watery fluids, so they depend on cilia, flagella, and pseudopods for survival.

Why do multicellular organisms transport systems?

Multicellular organisms need efficient transportation systems because simple diffusion would be too slow to transport nutrients and remove waste.