Range: Tropical waters worldwide Habitat: Coral and other burrowing areas Size: Up to 0.5 feet (15.24cm) long Diet: Phytoplankton and detritus Threats: Sea urchins, lobsters, and sea stars Life span: Thirty years or more

Transcript:

Today on Animal Fact Files, we’re talking about Christmas tree worms. You can give us the gift of Christmas by subscribing! Thank you to Panda Party 22 for today’s suggestion. Though they have a seasonal name, they can be found any time of the year, and they look just as colorful as any Christmas tree. Technically, each worm has two little Christmas tree structures to show, notice how they all appear in pairs? The “branches” of these coniferous look-a-likes are called radioles, and these are used for breathing as well as catching food which comes in the form of phytoplankton and detritus. Beneath this festive shrubbery, Christmas tree worms also have a “trunk”, though this part is rarely seen. I guess the whole tree metaphor sort of timbers at this point…

Christmas tree worms are found worldwide in warm tropical waters, and they’re almost always found living in a mutually beneficial relationship with coral. The coral they cohabit benefits from increased water flow created by the Christmas tree worms. The worms in exchange get a relatively safe place to live. It was originally thought that Christmas tree worms required coral in their lives, but recent research would suggest otherwise. Heck, they’ve even been found living with giant clams! The adult worms live inside a calcareous tube that can extend deep into the coral’s skeleton. That might sound like a bad deal for the coral, but if you’ll recall from our coral episode, the coral polyps living on the coral’s skeleton are only found in the outer section of the coral skeleton itself, meaning there’s some prime real estate beneath the surface layer.

A Christmas tree worm’s tube may extend more than half a foot (15.24 centimeters) into the coral’s skeleton, though the worm itself may never reach that length. Think about it this way, it helps to leave extra room in order to hide from predators like sea urchins, lobsters, and sea stars because they don’t really have any other means of escape. Christmas tree worm adults are sessile, and thus stay in one place their entire lives; because of this, it’s not uncommon to see a bunch of Christmas tree worms all hanging out in close proximity. This isn’t necessarily because they like chatting up the neighbors, but it does ensure their broadcast spawning is more likely to be successful.

Christmas tree worms tend to spawn during evenings of slack tides, which is the time when the water is least disturbed by tidal currents. This can help ensure eggs become fertilized. Fertilized eggs take about a day to develop into swimming larvae. As larvae, Christmas tree worms can eat plankton in order to survive until they’re ready to settle and become adults. It can be days to weeks before a larva decides on the perfect spot, which can be determined through the hardness of the substrate as well as the availability of neighbors who would later on help to create future generations. And I thought choosing a major in college was tough. If everything works out, these invertebrates can live to be more than thirty years old.

For more facts on Christmas tree worms, check out the links in the description. Give a thumbs up for weird animals, and thank you for watching Animal Fact Files.