Vegetation on the breakwater has resulted either from natural re-colonisation or has been planted by local community groups.
Many plants, including Coast Saltbush, Rounded Noonflower, Austral Seablight, Bower Spinach and Beaded Glasswort, are established on the breakwater and are adapted to the harsh salty and exposed environment.
Extensive seagrass beds surround the structure and provide a nursery area for many types of marine fauna, including the little penguins and the rakali.
Up to one hundred little penguins make the St Kilda breakwater their home, remarkable given their proximity to the urban centre of Melbourne.
The St Kilda breakwater was constructed for the 1956 Olympic Games to provide a safe harbour for yachts and provides a rocky and isolated location for the little penguins to live. The first breeding record of a pair was recorded in 1974, making the St Kilda breakwater the only confirmed breeding site for the penguin that is directly attached to the mainland.
Little penguins spend most of their time in the waters of the bay feeding on pilchards, anchovies and other small fish. At night they return quickly to the safety and protection of their burrows within the breakwater.
Penguins are not the only animals to have colonised the breakwater. Native water rats (rakali) can sometimes be seen among the rocks or swimming in the shallows.
The breakwater is also an important roosting platform for many other sea-bird, including cormorants and gulls, that feed in the surrounding waters.