Study: Algae can form stable groupings

CAMBRIDGE, England, April 21 (UPI) -- Scientists at England's Cambridge University have discovered freshwater algae can form stable groupings in which they dance around each other.

The researchers said they studied the multicellular organism Volvox, which consists of approximately 1,000 cells arranged on the surface of a spherical matrix about half a millimeter in diameter. "Each of the surface cells has two hair-like appendages known as flagella, whose beating propels the colony through the fluid and simultaneously makes them spin about an axis," the scientists said.

The researchers led by Professor Raymond Goldstein discovered colonies swimming near a surface can form two types of "bound states"; the "waltz", in which the two colonies orbit around each other like a planet circling the sun, and the "minuet," in which the colonies oscillate back and forth as if held by an elastic band between them.

Using a mathematical analysis, the scientists discovered the dancing patterns arise from the manner in which nearby surfaces modify the fluid flow near the colonies and induce an attraction between them.

The scientists said their findings constitute the first direct visualizations of the flows, which have been predicted to produce such an attraction.

The research that included doctoral student Knut Drescher, postdoctoral researchers Idan Tuval and Kyriacos Leptos, Professor Timothy Pedley, and Professor Takuji Ishikawa of Japan's Tohoku University appears in the journal Physical Review Letters.