Bootstrap Caulerpa (Caulerpa filiformis) and Common Kelp (Ecklonia radiata). Fairy Bower, Manly, NSW
Bootstrap Caulerpa is easy to recognise because of its brilliant green colour. It is the dominant macroalgae on many rock platforms in the Sydney area. There is some evidence that it is much more common now than in past decades, and that it is rapidly displacing other species. This suggests it is a recent introduction, probably brought accidentally from southern Africa where it occurs extensively. (Its cousin C. taxifolia is a particularly aggressive introduced pest in NSW).
Few animals eat Bootstrap Caulerpa in NSW. Some herbivorous fish will eat it only if no other algae is available. The small green sacoglossan Oxynoe viridis is one of the few animals known to prefer it.