Video: Watch an Algae Cell Turn Itself Inside Out

Algae embryos in the genus Volvox. Stephanie Hohn, Aurelia R. Honerkamp-Smith, and Raymond E. Goldstein

Sometimes algae embryos look like mushrooms, and sometimes they look spherical. The act of shifting between these shapes helps them develop into their final form.

Science have now for the first time captured this process on film, in 3-D. Watch as these little algae-to-be turn themselves inside out, a perplexing act of biological ingenuity that researchers have struggled to understand.

In a study published this week in the journal Physical Review Letters, Cambridge University scientist Stephanie Höhn and her colleagues have mathematically described how this inside-out trick works. Their analysis shows that, in order for the algae to invert themselves, one-half of the embryo's hemisphere contracts while the other stretches out.

The study helps to better understand the process of invagination, a "fundamental event" common to many organisms "in which a sheet of cells folds inside, triggering the formation of an internal cavity," according to an analysis of the paper published in the same journal. Invagination is part of cell growth and organ formation in many organisms. Seeing how algae do it could help scientists better understand the growing process in many other plants and animals.