Summary:
- Plant-like protists are called algae (singular, alga).
- They are a large and diverse group.
- Some algae, the diatoms, are single-celled.
- Others, such as seaweed, are multicellular.
- Algae, like plants, obtain their energy through photosynthesis.
- They are the main component of phytoplankton and contribute to the food base of most marine ecosystems.
- Although not plants themselves, algae were probably the ancestors of plants.