Purple haze over Rotto discovery
A NEW species of barnacle has been named and described after being discovered living on reefs off Rottnest Island.
The striking purplecoloured barnacle membranobalanus porphyrophilus was first identified in WA and was later found in the South Australian Museum collection, having been collected in waters around Kangaroo Island.
WA Museum curator of aquatic zoology Andrew Hosie said the barnacle was discovered during fieldwork by the museum’s aquatic zoology department.
“Unlike a typical barnacle that attaches to rocks, membranobalanus porphyrophilus lives solely in marine sponges,” he said.
“This means it is completely embedded within the sponge body, with only a small hole allowing the barnacle to extend its feathery limbs, called cirri, into the surrounding water to trap food such as plankton.”
Membranobalanus porphyrophilus is known to inhabit only one species of sponge, the vibrantly purple Spheciospongia purpurea, which is endemic to southern Australia and found from Geraldton to southern NSW.
“The fascinating thing about this barnacle is that the shell plates should be white and the body mostly transparent, but they are deeply stained by the pigments of the host,” Mr Hosie said.
“The sponge even retains the colours when dried or preserved in ethanol.”
The barnacle’s species name, porphyrophilus, translates as purpleloving in reference to the colouration of the only known host.