Animal Species:Acorn Barnacle

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 Barnacle

Dr Isobel Bennett © Australian Museum

Standard Common Name

Acorn Barnacle

Identification

Acorn barnacles like Chthamalus antennatus look like miniature volcanoes.

Size range

1.2 cm

Distribution

Acorn barnacles are found in New South Wales, Victoria and Tasmania.

Habitat

Acorn barnacles live on intertidal rocky shores.

Other behaviours and adaptations

Acorn barnacles are extremely abundant and gather in large groups towards the high-tide mark on rock platforms.

Mating and reproduction

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.

Classification

Species:
antennatus
Genus:
Chthamalus
Family:
Chthamalidae
Suborder:
Balanomorpha
Order:
Thoracica
Subclass:
Cirripedia
Class:
Maxillopoda
Subphylum:
Crustacea
Phylum:
Arthropoda
Kingdom:
Animalia

What does this mean?


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Tags barnacle, crustaceans, invertebrates, arthropods, wildlife of sydney, identification,

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