One of the most mesmerising features of the microscopic organisms that live in wet places is the variety of ways in which they get around. Some use rhythmically beating hairs (cilia), for motive power. Others, like amoeba, simply flow over flat surfaces. Euglenoids – minute photosynthetic organisms that are ubiquitous in wet places – blur our concepts of what is an animal or plant (they are neither) and can crawl over wet surfaces and even change shape, but mostly they use a long flagellum, whipping it through the water as the driving force for their movements. One of the most extraordinary euglenoids is this one, called Phacus, which adds an extra twist to the wacky ways of moving by being twisted into a helix. So when it beats its flagellum it corkscrews through the water, as you can see in the video. It's less than a twentieth of a millimetre long.
