Polychaetes



Image: Chris Glasby

As only 30 per cent of polychatea species are known, Chris Glasby and Charlotte Watson, representing the Museum and Art Gallery of the Northern Territory, are very excited at the prospect of what they may find on this field trip.
Polychaetes are a class of annelid worms. Polychaeta means "many-bristled" and the animals are sometimes referred to as ‘bristle worms'.

Chris and Charlotte, specialists in polychatea, have already found many polychaetes and they're expecting half to two-thirds of those found on the island to be new species.
"At the moment we have two ‘morpho' species [not formally described] within the genus Nematonereis, family Eunicidae," Chris said.
"This is a genus that is not well known in Australia. We are distinguishing the new forms morphologically – one has a long antenna and one has a short antenna," he said.
"At the moment we're not sure that they're new but we think they are, so that's exciting. And that's not the only thing we're going to find. There are going to be new species here."


Image: Chris Glasby

Polychaetes are related to leeches and earth worms as they all come under the Annelida classification which has three classes of segmented worm – Polychaeta (bristle worms), Oligochaeta (earth worms) and Hirudinea (leeches).
There are 82 families of polychaetes, and Chris estimates there are around 12,000 known species.

The polychaetes often have eyes, antennae and mandible jaws. They grow to different sizes but the Nematonereis that Chris and Charlotte are researching tends to be a small worm, growing to approximately 15 millimetres. They usually feed on alagae and tiny crustaceans such as tanaids.
The polychaete's main predator is fish.
"Fish nose-down and suck up polychaetes from the coral rubble," Charlotte said.
The worms are collected by hand using scuba on dives around the island. The scientists collect the loose rubble and seaweed to discover what lies within.
"You can have hundreds of polychaetes in one micro habitat, and we sort it in the lab to find these interesting things," Charlotte said.
Charlotte's favourite polychaete is the family Chrysopetalidae – and seeing a photo of it, you can see why. The beautiful jewel-like appearance and myriad metallic colours is quite glamorous for something called a ‘segmented worm'.
For more information on Chris and Charlotte's work at the museum visit the museum's website at: http://www.nt.gov.au/nreta/museums/index.html