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You are here:   animal list > Spirobranchus giganteus




Spirobranchus sp.

Christmas Tree Worm

Christopher De Martini (2011)


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Physical Description


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Local Distribution and Habitats

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Morphology and Physiology

External Morphology

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Conservation and Importance


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Local Distribution and Habitats

On Heron Island, there was a large population of Christmas tree worms present within waters surrounding the sand island. They are obligate with coral, in particular, Acropora spp. Therefore, the fundamental limitation of the distribution of Christmas tree worms was the availability of an appropriate host. Most other coral genera present did not accommodate them, suggesting that either there is a cue given by the Acropora spp. which encourages or supports this relationship or there is selective pressures acting against Christmas tree worms settling on other sclereterian coral types.

Whilst they were able to reside in any area of the reef zones that possessed Acropora spp coral, the highest populations were observed on the reef crest of the island. The reef crest, otherwise known as the algal ridge, of any coral island is a high energy area subject to changes in the hydrology of the area due to its shallow waters. A reason that the worm may prefer these areas is because it may eliminate the chance of predation by reducing the capacity for predators to access the area. Another possible explanation could be that the high energy of the area brings along with it an abundance of nutrients (i.e. phytoplankton), sediment and oxygen which is likely to increase the chances of the worms survival.

Once the worms are ready to settle after having dispersed, they tend to aggregate near one another. When out in the field, it is rare to find a lone worm within a meter radius of it. This is not random, but intentionally done done to maximize the potential for reproduction in future generations. It is common for many worms to settle and metamorphose onto the same piece coral.