On any visit to the rocky shore in Sydney, you are almost guaranteed to see barnacles. You may even see several species on the one occasion.
Acorn barnacles like Chthamalus antennatus look like miniature volcanoes.
Acorn barnacles live on intertidal rocky shores.
Acorn barnacles are found in New South Wales, Victoria and Tasmania.
Other behaviours and adaptations
Acorn barnacles are extremely abundant and gather in large groups towards the high-tide mark on rock platforms.
Barnacles have an infamous reputation for their large penis size. Their reproductive organ may be up to 10 times their body size, a useful adaptation for fertilising adjacent females. Most barnacles are hermaphrodites, having both male and female reproductive organs. Barnacles clustered together may exchange sperm. Barnacles separated by long distances are either not fertilised or fertilise themselves to produce clones.