How does multicellularity evolve? Scientists who study a family of green algae that includes unicellular Chlamydomonas and multicellular Volvox are beginning to find answers to this question.

“Although C. perkinsii is a unicellular species, this behavior shows that multicellular coordination and differentiation processes are already present in the species, well before the first anima ...

zooxanthellæ are abundantly present within the cells of the digestive glands. Here then is another animal digesting intracellularly and harbouring a unicellular green alga within its tissues.