Treasure of the Month – Worm Wishes for the Holidays

Our treasure of the month: the “Christmas tree” worm. © LIB, J. Moore


As bright lights, colorful decorations, and holiday markets appear all around us, we at the LIB are celebrating some of the festive specimens in our Annelida collections.

The most well-known members of the marine annelid family Serpulidae are the “Christmas tree” worms of the genus Spirobranchus, whose brightly colored and spiral-shaped radiolar crowns are reminiscent of a pair of Christmas trees. You may have seen these conspicuous worms peeking out from corals on tropical reefs, using their blue, yellow, orange, or red “Christmas tree” head appendages to capture tiny food particles from the water current above them. When disturbed, the worms retract quickly into their calcareous tubes which they can seal up with a special lid made from a modified tentacle. Christmas tree worms are not just pretty decorations on coral reefs. Rather, they clean the water and make food available to other organisms by drawing nutrients from the water column into the bottom.

The LIB Annelida collection contains 652 specimens from the family Serpulidae, including the original type material for 22 species. Type material is critical to systematics and taxonomy, as these specimens represent the physical definitions of a species, and the LIB Annelida collections are home to approximately 3,500 type specimens.

As part of an expedition to Oman in late 2022, LIB Annelida curator Dr. Jenna Moore collected many Spirobranchus specimens, including the one shown above, in addition to several hundred other annelid specimens. The expedition was an international collaboration led by researchers at the Florida Museum of Natural History and the Smithsonian Institution to describe, characterize and study the marine biodiversity of Oman and the western Indian Ocean. Oman is a remarkable place, with highly variable habitats and unusual current patterns which drive an incredibly diverse and unusual marine fauna. The annelids from Oman are currently being identified and studied by Dr. Moore and other taxonomic experts around the world, to better understand the diversity of marine Annelida and their biogeographic patterns.

The Spirobranchus specimens from Oman are not the only ones getting into the holiday spirit. Others are ready for the fireworks of the New Year, like this “feather-duster” worm in the family Sabellidae. Sabellids are close relatives of Christmas tree worms, and their spectacular radiolar crowns are similarly colorful, but look more like fans (or fireworks!) than Christmas trees.

A “feather-duster” worm (Sabellidae) with a radiolar crown like fireworks.  © LIB, J. Moore


Other worms seem to have a sweet tooth. This Eunice sp., with its candy-cane patterned antennae, has a formidable set of jaws hidden in its throat. The evolution of these jaw structures is another ongoing research focus in the LIB’s Section Annelida.

The candy-cane patterned antennae and cirri of Eunice sp. © LIB, J. Moore


These specimens represent a small part of the remarkable diversity of marine Annelida uncovered in Oman, including several species new to science which will soon be described. Characterizing biodiversity through taxonomy is critical to understanding its change, and represents a major research goal at the LIB.

However you celebrate, the LIB’s Section Annelida extends “worm” wishes to all for the holiday season and new year.


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