5 facts about the whimsical Christmas tree worms

Also known as Spirobranchus giganteus, Christmas tree worms are marine worms that live on tropical coral reefs around the world. One look at them and it’s easy to know how they got their name.

christmas tree worms

Here are 5 facts about these marine worms that look straight out of a fairytale.

They live inside corals

Christmas tree worms are commonly found embedded in living corals, such as brain corals. They create a burrow by boring a hole into the coral before secreting a calcareous tube around its body for extra protection.

Gills that catch dinner

Each worm has two brightly colored Christmas tree-like crowns that protrude from its tube-like body.

These Seussian crowns are composed of feathery tentacles known as radioles that are part of their highly adapted respiratory system. Apart from breathing, these external gills are also used for catching food such as phytoplankton floating in the water, before passing them down to their mouth.

Short and skittish

These worms only grow to about 1.5 inches. They are also known to quickly retract into their tubes when they sense movement in the water. Once the coast is clear, they slowly re-emerge with fully extended plumes.

They reproduce sexually

Male and female Christmas tree worms reproduce sexually by releasing their sperm and eggs into the water. The eggs are fertilised as they drift with the currents before developing into larvae that settle on coral heads and burrow inside.

Population may be affected by ocean acidification

While Christmas tree worms are not classified as an endangered species, ocean acidification and warming could soon change that. Ocean acidification may endanger the worms by reducing calcium carbonate minerals in seawater – a key ingredient in the calcareous tubes of Christmas tree worms.

Christmas tree worms can be found at S.E.A. Aquarium. Just make your way to the Focus Globes directly opposite the Mangrove Habitat.

From all of us at S.E.A. Aquarium, have a very Merry Christmas!

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