Golden petals of the sea

A polychaete of the genus Spirobranchus.


24 May 2010
Polychaetes, or segmented worms, are amongst the most common and widespread invertebrates in the oceans.
There are species that live in the coldest darkest abyss, such as the three-metre-long cold seep tube worm Lamellibrachia luymesi; species such as the Pompeii worm, Alvinella pompejan, that tolerate extreme high temperatures near hydrothermal vents on the floor of the Pacific Ocean; even one as-yet-unclassified species found by robot probes at 10,902 metres underwater, one of the deepest areas of the oceans explored by humans.
On coral reefs, different polychaetes species can be found burrowing into dead corals, moving freely around coral rubble and algal holdfasts, in tubes anchored to rubble or algae, or swimming amongst the plankton near the surface of deeper waters out from coral reefs.
Several polychaete families are named after nymphs and goddesses, such as Nereis, commonly known as the clam worm, and Aphrodite, known as the sea mouse. Others are less nobly titled, such as a species of Osedax dubbed the "bone-eating snot flower".
But of all of the approximately 80 families of known polychaetes, polychaete expert Charlotte Watson of the Museum and Art Gallery of the Northern Territory has picked her favourite: the Chrysopetalidae.
"The Chrysopetalidae are pretty small, from two to 10 millimetres in length. Their hairs are expanded structures, like little leaves, that cover their backs and fit together like tiles on a roof. They are coloured gold and silver and bronze. Chrysopetalidae means golden petals in Latin," she explains.
This is Charlotte's fourth CReefs expedition. She estimates there have been 30 new chrysopetalid species found on CReefs expeditions, as well as a new species of Syllidae found from Lizard and Heron Islands.
"It's about five millimetres long, with brightly-coloured yellow and orange lobes on the back, with little white tips on the end of the lobes. The only other species of this genus was collected in New Zealand in the 1950s, so this is a new species and record for the tropics."
Charlotte has named the species Clavisyllis yongei, after Yonge Reef, Great Barrier Reef, were it was first discovered.