Tube Worms

Christmas tree worms

Among the many tube worms on the Great Barrier Reef is the brightly-coloured Christmas tree worm (Spirobranchus giganteus), which is a favourite with divers and snorkellers.

The 'Christmas trees' are gills that filter food from the water. These worms are very sensitive to shadows and vibrations - quickly pulling into their tube and closing a 'trap door' over the top.

Christmas tree worms spawn during the slack tide of the first lunar quarter in October. The larvae settle on coral colonies where a polyp has been damaged (by a parrot fish scraping coral, for example) and secrete a tube. The worm does not bore into the coral - rather the coral grows over the tube. The worm grows at the same rate as the coral to maintain its place on the coral's surface. It is usually found living on the massive corals of the Porites species.