Colourful Christmas tree worms are captivating during any dive, adding a touch of festive magic to coral reefs around the world.

What are Christmas tree worms?

They might look like colourful Christmas trees but they’re actually segmented worms. Most of their structure is hidden in tubes within the coral with only their crowns or Christmas trees protruding. These creatures can live for 40 years!

Christmas Tree Worm, Spirobranchus giganteus
Christmas Tree Worm, Spirobranchus giganteus, by Jill Studholme

Their scientific name is Spirobranchus giganteus, meaning Giant Spiral-Gills. Although the visible part is only 1.5 cm long, together with its hidden part it is in fact one of the largest worms in its family. The branching crown is important for respiration, hence the “spiral-gills” name.

Each worm has two crowns or Christmas Trees. The worms come in a myriad of colours, but an individual’s two crowns are always the same colour. As well as being used in respiration, the the feathery Christmas Tree gathers food, wafting it down to the worm’s mouth.

Christmas Tree Worm  by Tim Nicholson of SCUBA Travel
Christmas Tree Worm by Tim Nicholson

On sensing danger, the worm quickly retracts its crown into its tube in the coral and closes the entrance with a trapdoor called an operculum. It will stay down there for about a minute, before re-emerging very slowly to check that the danger has gone.

There are both male and female Christmas tree worms and they are choosy; spending their entire life on the same coral – often massive porites. They are important for the health of coral reefs and help protect corals from invasive sea stars whilst also preventing the coral being overgrown with algae.

Where do they live?

The great thing about Christmas tree worms is that you can see them around the world on most tropical reefs. They’re easy to find and very photogenic, making them great subjects for macro photography. As long as you have the patience to wait and not disturb them into shooting back into their tubes. You might see them down to depths of 30 m.

Where can I dive with Christmas tree worms?

There are many great diving destinations where you’ll find Christmas tree worms, whether you want to dive close to home or visit far-flung paradise islands. Here is our pick of the best:

Somosomo Strait, Fiji

The Somosomo Strait is one of Fiji’s best-known dive destinations. The soft coral growth is truly spectacular and the vertical walls are absolutely covered in corals and sea fans. Relax into the current and you’ll find yourself drifting along multicoloured walls and enjoying big pelagics such as dolphins, manta rays, whitetip sharks, barracudas and more. Purple Wall is not to be missed for a dense wall of purple soft coral trees and Rainbow Reef has plenty of Christmas tree worms. The real highlight is the Great White Wall; a wall so covered in white soft corals it looks like a wall of snow.

The Fiji Aggressor and Reef Endeavour offer year-round dive and cruise trips to a variety of Fiji’s top dive destinations.

The Cayman Islands

Scuba diving the USS Kittiwake is a must when you’re diving in the Cayman Islands. This US Navy submarine rescue vessel is an impressive wreck sitting in crystal clear water, and has 5 decks, 2 bridges and a huge interior to explore. There are numerous fish at the top of the wreck, thanks to a complete fishing ban in the area, plus green sea turtles, Caribbean reef sharks, stingrays and occasional hawksbill turtles in the surrounding waters. The hull of the wreck is covered in colourful corals, with plenty of Christmas tree worms to find.

Diving the Cayman Islands
Diving the Cayman Islands

Little Cayman’s Bloody Bay Wall is one of the best places for wall diving and drops to over 914 meters (3000 feet) depth, offering one of the most colourful Cayman Islands dive sites. It is another great place to spot Christmas tree worms amongst the numerous corals.

The Cayman Aggressor V offers year-round Cayman Islands safaris, including Family Weeks and Solo Traveller weeks.

Wakatobi, Indonesia

This protected UNESCO Marine Biosphere Reserve stretching across 1.39 million hectares, offers exceptionally clear water and flourishing reefs. Go Wakatobi liveaboard diving and you’ll be surrounded by hundreds of fish species as you explore the impressive range of corals. There are plenty of colourful Christmas tree worms to be found but don’t forget to look up for passing manta rays and whale sharks. Visit from November to April and you might even see short-finned pilot whales. There are a variety of Indonesia liveaboards to choose from.

Christmas Tree Worm by Tim Nicholson
Christmas Tree Worm by Tim Nicholson

Bahamas

Bahamas diving is renowned as a top destination for big animal encounters; especially at Tiger Beach, where you’ll find yourself surrounded by numerous large sharks. There are also colourful reefs and wrecks to explore, plus wall diving and swift drift dives. Eleuthera Island, with its pink beaches and ancient reefs, is well worth visiting and hosts Christmas tree worms at Tunnel Rock dive site.

The Phoenix catamaran caters for just 8 guests and offers exciting sailing and diving safaris to Exuma & Eleuthera Reefs.

Micronesia

Micronesia scuba diving really is diving in paradise. The forest-covered islands tucked away in the Western Pacific Island host everything from numerous wrecks to exciting current dives, big wall diving and cave systems. Whilst Truk Lagoon may be the main wreck diving destination, Palau also has some huge wrecks, plus channels, drop offs, caves and reefs to explore. Keep your eyes open for the colourful Christmas tree worms on the reefs as you take in the variety of life around you.

The Solitude One and Palau Siren both explore the best dive sites of Palau.

Oman & Djibouti

If you’re looking for somewhere easily-accessible from the UK, be sure to check out Oman and Djibouti. Both of these are up-and-coming liveaboard diving destinations and have plenty of coral reefs with Christmas tree worms. Visit at the right time of year and you can be enjoying warm-water diving whilst exploring uncrowded dive sites well off the beaten path.

Christmas Tree Worms in Djibouti. Photo by Tim Nicholson
Christmas Tree Worms in Djibouti. Photo by Tim Nicholson

This article was written by divers and writers at LiveAboard.com. Additional material by Jill Studholme. Top photo credit: Nick Hobgood, CC BY-SA 3.0.

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