Crypsis
To aid survival, the Christmas tree worm is able to quickly retract into its calcareous tube with the slightest physical (i.e. light sensitivity, direct touch) or chemical cue. This sometimes makes them difficult to spot within the environment. When the worm feels like the conditions are suitable, it slowly extend out of it tube over the course of a minute or two until it has fully branched out to ensure it is safe from any disturbance.
Even without this mechanism, Christmas tree worms only expose their prostomium and hide their tube within the coral host. This can make identifying them difficult for many people and organisms with the naked eye.
It could also be speculated that the vibrant colouration of the worms may help reduce their visibility to other predators. However, without spectral testing of the many potential predator species, this would be difficult to determine. |