This image shows freshwater algae called Volvox. The name comes from the Latin for ‘I roll’, referring to how these spherical organisms roll through the water, propelled by flagella. These tiny whip-like structures protrude through the glycoprotein matrix, which surrounds up to 50 000 cells in each organism.
Each Volvox is a hollow sphere with a single layer of cells at the periphery. As explained in ‘Upgrade’, this makes for a very efficient structure. The light and carbon dioxide used during photosynthesis can easily reach all of the cells, and the oxygen they produce can diffuse effectively into the surrounding water.
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