The Amazing Undersea Christmas Tree Worms

Christmas Tree worms, Turks and CaicosPhoto: Alain Feulvarch

Who says that other species don’t celebrate Christmas? What about these amazing creatures. Called Christmas Tree Worms (Spirobranchus giganteus) they live on and in coral.

Yellow and blue Christmas tree worms (Spirobranchus giganteus) from East TimorPhoto: Nick Hobgood

Their incredible twin spirals are actually their respiratory and feeding apparatus, the body of the worm being a tube (it belongs to the tube family of worms) that bores down into the hard coral and lives there. Once they have bored their home, they then secrete a calceous or bony type structure to provide additional protection.

Christmas Tree wormsPhoto: aquaimages

In fact the plumes and appendages on them can retract right into the coral (as the video shows), which they do at the smallest shadow or disturbance.

Christmas tree WormsPhoto: Ian Armstrong

The colorful spirals are two branches, and they are made up of feather-like tentacles called radioles. Tiny hairs on them allow the worm to feed by the filter method, eating tiny plankton and other marine microorganisms as the current pushes them into their vicinity. The radioles are commonly called gills because even though feeding is their main function, they are also used for respiration.

Christmas Tree Worm (Spirobranchus giganteus) in Porites coral. Admiralty, Osprey Reef, Coral SeaPhoto: Richard Ling

The tiny little “feet” you can see in the pictures, that make some look like two Christmas trees dancing, are not appendages for them to go and take long walks, but simply to move and stretch around their perimeter, perhaps for a particularly tasty bit of plankton otherwise just out of reach.

Corals and The Christmas tree worms, Spirobranchus giganteus. The picture was taken in Papua New Guinea.Photo: Mila Zinkova

They come in many colors, reds, pinks, blues, oranges, whites, yellows and purples, to name a few, and average 3.5 cm. Found in tropical seas across the world they are easy to spot if you are lucky enough to be a diver and are available for aquariums as well, if not.

Spirobranchus giganteus (assorted Christmas tree worms)Photo: Nick Hobgood

This image looks like a misshapen large Christmas tree, decorated with tiny Christmas trees and ready for presents to sit under it. Mother Nature surely is full of miracles and these little fellows are particularly cheerful and beautiful examples of her work.

Sources: 1, 2