Elminius modestus

Taxobox
name = "Elminius modestus"

---

image_caption = "Elminius modestus" and "Semibalanus balanoides"
image_width = 240px
status =
regnum = Animalia
phylum = Arthropoda
subphylum = Crustacea
classis = Maxillopoda
ordo = Sessilia
familia = Balanidae
genus = "Elminius"
species = "E. modestus"
binomial = "Elminius modestus"
binomial_authority = Darwin, 1854

"Elminius modestus" is a barnacle of the family Balanidae, native to Australia and especially New Zealand. It is found intertidally on solid surfaces around southern Australia and New Zealand, often forming dense mats, except where there is intense wave activity.

"Elminius modestus" is a small barnacle, protected by four calcified shell plates, attached to a wide range of substrates - rocks, metal, wharf pilings, and mollusc shells. Its general shape is low and conical with a diamond-shaped opercular aperture. In young barnacles the shell plates have a star-shaped base - older specimens have marked vertical ridges that give the barnacle an irregular, roughly circular margin.

"Elminius modestus" has become an invasive species in Britain and Europe. It was first described at Chichester Harbour in 1946, and is thought to have been transported in the ballast water of ships during World War II. It rapidly spread throughout Britain and northern Europe, being found on almost all shores of Britain by the 1970s. "Elminius modestus" not only competes with native British species, particularly "Semibalanus balanoides", but has colonized some sheltered and estuarine habitats not previously inhabited by them. However, "E. modestus" is not able to colonise high wave action areas and these remain relatively safe for endemic barnacle species.

Coloration is opalescent greyish-white in juveniles and spat (newly settled and metamorphosised larvae) while adults are a drab grey colour.

Maximum size is about 10 mm in diameter.

References

* [http://www.marlin.ac.uk/species/Elminiusmodestus.htm Marine Life Information Network for Britain & Ireland]
* Miller M & Batt G, "Reef and Beach Life of New Zealand", William Collins (New Zealand) Ltd, Auckland, New Zealand 1973