Ecology
Marianina rosea is a member of the cryptic community of invertebrates inhabiting low intertidal coral reefs of Heron Island (Marshall & Willan, 1999). Growing to a maximum of only 14mm in length, and brightly camouflaged to match the array of colours represented by colonial communities of ascidians, sponges and soft corals, this species of nudibranch is extremely difficult to identify on coral boulders. They are commonly found residing under dead coral slabs and boulders of the reef crest up to depths of 20 metres, and when abundant found in mating pairs (Marshall & Willan, 1999). The ephemeral lifestyle of this species means that populations are heavily reliant on the abundance of food. In most cases, individuals will never find a mate to reproduce with in their lifetime, making it difficult to research the ecology of this species.
Intertidal reef crest at Fourth Point, Heron Island, September 2013.
The specimen of M. rosea located during September of 2013 was found foraging underneath a small coral boulder collected from the reef crest at Fourth Point. This individual, measuring 5mm in length, was found to be solitary with no other partner or mate in sight. Upon further investigation of the reef crest, only the one individual of M. rosea was located during the course of the week at Heron Island. The art of camouflage seems to be an essential component to the survival of this elusive species of nudibranch, with its strikingly bright magenta colouration allowing the animal to match the colourful invertebrate communities that it forages upon (Marshall & Willan, 1999).
Original underside of the coral boulder that Marianina rosea was located on at Heron Island, September 2013. |