algae

Everyday

1. Simple plant-like living things, usually green, brown or red, that grow in water or damp places and make their own food from sunlight. tree →
2. The green slime or scum seen on ponds, rocks, fish tanks and swimming pools. tree →
3. Seaweeds are large algae. tree →

In the lessons

In science, algae are producers at the bottom of water food chains: tiny fish and other creatures eat them, and they give off much of the oxygen we breathe. In everyday life they make ponds green and paths slippery. In safety: rocks covered in algae are very slippery; some algae (blue-green algae) in lakes can be poisonous to people and dogs — obey warning signs. Phrases: algae bloom, green algae, pond algae.

Examples

• Algae turned the pond water bright green. tree →
• Be careful — the rocks are slippery with algae. tree →
• Seaweed is a kind of algae that grows in the sea. tree →
• Algae make food from sunlight, like plants do. tree →
• Tiny animals in the sea eat algae. tree →
• We cleaned the algae off the inside of the fish tank. tree →
• The sign warned that toxic algae made the lake unsafe for swimming. tree →

Note

«Algae» is plural; the singular «alga» is rare, so people say «some algae» or «a type of algae». Pronounced AL-jee (UK also AL-ghee). Algae are not true plants in modern science, but they make food by photosynthesis like plants.