Kingdom: Animalia
Phylum: Porifera (sponges.)
Class: Demospongiae
Order: Poecilosclerida
Family: Raspailiidae

Genus/species: Trikentrion flabelliforme

GENERAL CHARACTERISTICS: White horizontal lines cover a striking red body. Its tree-like base is covered by a white web-like symbiont with a hexacoral from the genus Parazoanthus (order Zoanthidea).

DISTRIBUTION/HABITAT: Arafura Sea, a shallow body of water sandwiched between Australia and New Guinea.

DIET IN THE WILD: T. flabelliforme is a filter feeder using its choanocytes or collar cells to filter particles and dissolved substances from seawater.

REMARKS: Parazoanthus is a suspension feeder as its polyps capture food particles from the water. The tissue of Parazoanthus is connected to the skin or pinacoderm of its host sponge, with tissue integration varying between different combinations of sponge and the coral.

Parasitism seems a likely option, where the symbiotic coral benefits at the expense of its host sponge. For example, the coral may impair the sponge’s ability to pump water through its system, which is vital to sponge nutrition, waste removal and gas exchange. Commensalism is also possible, where the coral benefiting while having a neutral effect on the sponge.

T. flabelliforme is difficult to grow in captivity but has been growing in the California Academy Steinhart Aquarium system for a year showing signs of good health.


California Academy of Sciences Steinhart Aquarium Hidden Reef
Charles Delbeek curator, 2018

Ron’s flickr