Later, animals - multicellular organisms - evolved ... perkinsii, an ancestral species of protist. This unicellular organism separated from the animal evolutionary line more than a billion ...

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.

- in most modern classifications, replacement for the Protista; includes: Protozoa; Euglenophyta; Chlorophyta; Cryptophyta; Heterokontophyta; Rhodophyta; unicellular protists and their descendant ...