Bull Kelp Southern Bull Kelp (Durvillaea potatorum) thrives amidst the relentless tides and swells. Remarkably resilient, attaching to rocky reefs by a large disc-shaped holdfast, their dark brown leathery branches (thallus) can reach a lengths in excess of ten metres. Individual bull kelps can weigh up to 75kg! Giant Kelp Giant kelp (Macrocystis pyrifera) are an iconic canopy forming seaweed that can grow over 35 metres long and up to half a metre each day. Like trees in a forest, giant kelp modifies the environment and the resulting conditions favour a huge diversity of other species. Golden Kelp The golden kelp (Ecklonia radiata) forms the backbone of the Great Southern Reef. With strong holdfasts gripping tightly to the shallow, rocky surfaces, these highly productive algae dance gracefully in the high swell conditions where they flourish. Learn More Sign up with your email address to receive news and updates. Email Address Sign Up Thank you!