There are three main groups of seaweed: brown, red, and green. Their names give a general idea of their colour, but not all seaweeds look exactly that colour. For example, some red seaweeds can look pink or purple, and brown seaweeds may appear yellow‑brown.

Seaweed colour is also linked to where different types grow in the water. Red seaweedscan often grow deeper in the ocean because they are able to use the smaller amounts of light that reach greater depths. Green seaweeds are usually found near the surface where there is plenty of sunlight. Brown seaweeds, including kelps that form underwater forests, are commonly found in shallow coastal waters and mid‑depth zones. Giant kelps can grow from depths of up to around 30 metres all the way up to the surface, forming tall underwater forests where there is enough light for photosynthesis.

Now it’s time for students to use what they have learned in a creative way. Invite them to draw a reef inspired by the Great Southern Reef, showing the different seaweeds and the wide variety of marine life that makes the reef so colourful and full of life. Remind students to use colours, shapes, and details to bring their reef to life, combining their knowledge with their own creativity and imagination.