Tag Archives: christmas tree worms

Annelids and molluscs are cool, marine debris is not 

DAY 5 — Another full day of field biology! Starting with fried jack and fresh fruit for breakfast plus a leisurely coffee with Tian-Tian and Sarah. Our departure was postponed because of the windy conditions, so we listened to Damien talk about annelids and mollusks. 

Instead of heading out on the boat for an explanation of reef zonation, we suited up and walked through the “Mangroves of Death” to the back reef. We planned to assess the presence of Christmas tree worms (Spirobranchus gigantea), trying to answer the question: do Christmas tree worms show a host preference for stony coral? We hypothesized that more Christmas tree worms would be found on brain corals and that more Christmas tree worms would be found on larger corals.

Collecting data was difficult on the shallow reefs; constantly being pushed around by the waves and crashing into rocks was an inconvenience. Adolfo found a Caribbean spiny lobster shell from a recently molted lobster, which was pretty cool. 

For a sponge update: I didn’t identify any new sponges among the patch reefs today. BUT Adolfo found a big, old dead coral specimen. See below. 


I’m pretty sure it’s a yellow tube sponge (Aplysina fistularis). 

I’m hoping that when we eventually get out to the reef crest and fore reef I’ll see some more new species of sponge. I’m still hoping for a barrel sponge (like the Giant Barrel Sponge, Xestospongia muta) or the Pink Vase Sponge (Niphates digitalis). 

After a delectable lunch, Isaac gave a lecture on marine debris. A fun fact: microplastics are thought to account for 90% of marine debris. Our next activity fit with the theme. We collected trash and marine debris from various locations around Middle Caye (11 people for 30 minutes, so 330 people-minutes). There was SO MUCH TRASH, especially plastics. Kind of a bummer.

We arrived back at the wet lab with our trash bags stuffed with plastic forks, bottles, toothbrushes, sandals, combs, Styrofoam pieces and much more. Waiting for us were several freshly collected and cut coconuts. Man, I love coconut. 

After a brief stint in the hammock, we sorted, counted, and weighed all of the debris. 2,460 pieces, or 18.46 kg, of plastic. 

Before dinner we played some beach volleyball. Look out for an EBIO 319 intramural team, coming SY 2018. 

Later in the evening, Scott and Adrienne set up lights in the water at the end of the dock. It was kind of eerie being out on the dock in the darkness, looking out over the huge ocean. The water was choppy because of the strong wind, but we were able to observe a bunch of fish and a sting ray. Also, we saw the bright, reflecting eyes of a crocodile lounging behind a log. 

Until tomorrow!

Worms and Trash (Day 5)

Today we attempted to recreate the experiment that a former TFB performed on host preference in Christmas tree worms. Christmas tree worms are colorful little annelids that live on the surface of corals. In that way, this was easier than the urchin experiment because they were much easier to see.  I saw another Sailor’s eye algae today during the experiment. That was the only time we spent on the reef today, so I didn’t have time to look for other algae species much.

Two Christmas Tree Worms on top of a brain coral.


Besides algae, I also got to see the molt of a Caribbean Spiny Lobster today and a Donkey Dung sea cucumber on the back reef. These are funny because they look like a donkey’s dung (or at least what I assume the dung of a donkey might look like). Tonight when we shone a dive light into the water (it was too rough for us to do a night snorkel), we saw a crocodile and a stingray, too.

A Donkey Dung sea cucumber.

For the last part of today, we collected, sorted, and weighed marine debris. It was shocking, and depressing, to me how much debris there was on Middle Caye because we are so so remote. After 30 minutes of collecting, we didn’t even make a dent in the amount of litter there was within the mangroves, let alone the amount there is in the world, Belize, or even just the amount on Middle Caye.

A large piece of marine debris that was found during our Christmas Tree Worm experiment.

We couldn’t do the night snorkel or go out to the reef crest today, so fingers remain crossed.

Comparative study

We leveled up today on our length and difficulty of our snorkeling projects. We visited patch reefs inside and outside the protected area and did transects for comparison. We also collected sea urchins in a 25 minute period, then measured and ID’ed them. Compared to the no-take zone, the unprotected zone had drastically fewer urchins, which starts to give you an idea of the breadth of human impact on some of these reefs.

To be honest, I got a little distracted during the urchin collected period because there were so many worms around! I saw about 20 christmas tree worms, two social feather dusters and one split-crown feather duster. They’re really beautiful little things. There was one coral in particular covered by about 10 christmas tree worms in a variety of colors—from blue-grey to yellow to orangeish-brown. If you wave your hand in front of them they tuck themselves inside their tube to hide, then slowly reemerge after a moment. There will be pictures to come.

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Sophia Streeter