By Catherine Drake, Invertebrate Zoology Lab

For those of you vertebrates who still have their holiday decorations up, here is an invertebrate you might enjoy learning about: the Christmas tree worm.  These polychaetes, Spirobranchus giganteus, are tube-building worms that have two “crowns” in the shape of Christmas trees, hence their name.

These appendages are an extension of their mouth and catch prey that swims by and then transport it by cilia to the worm’s mouth.  Additionally, the appendages act as part of the worm’s respiratory system, and are thus commonly referred to as gills.  Christmas tree worms are generally found in tropical waters and live within corals in calcareous tubes formed by the worms.