Rose-coloured Barnacle

Description:

Rose-coloured Barnacles spotted on the rocks with Black Nerite molluscs (Nerita atramentosa). Also known as Rosy Barnacle and Rose Barnacle, this is a tall, conical barnacle, normally creamy-white in colour, but when eroded has a pink tinge. There are four main wall plates, but the opening (orifice) is five-sided (pentagonal) in shape. Inside the plates is porous, broken by radial walls. Largest specimens to about 20 mm across and 12 mm high. This species occurs from New South Wales, to north-eastern Victoria and occasionally in north-eastern Tasmania, although the Qld Museum states it is also found in Western Australia and South Africa. Barnacles are arthropods, in the same major group as insects and spiders, and are most closely related to decapod crabs, prawns, lobsters and yabbies. PS: I originally misidentified this spotting as Surf Barnacles (Catomerus polymerus.

Habitat:

Occurs on most exposed rocky ocean shores exposed to high energy waves, at mid to low-tide levels. I believe this area is called the "barnacle zone". On some rock faces it may be found in huge numbers. These were spotted on the rocks at North Avoca Beach on the NSW Central Coast.

Notes:

Heavy wave action this particular day but crystal clear water.