Tag Archives: sea urchins

Passenger Fish

May 26, 2019

Today we started and completed a whole new experiment. To look at sea urchin community structure (and the indications it may have for herbivory and reef health), we went out and collected sea urchins in a bucket and recorded the species and diameter of each urchin.

During the search, I noticed several new hydroids! I saw what I believe to be a lot of Box Fire Coral (Millipore squarrosa), which is the third and last species of fire coral that I found to be common in the Caribbean.

I also spotted some Kirchenpaueria halecioides, a small hydroid that gets up to about one inch tall (see photo below) in addition to a possible Feather Bush Hydroid (Dentitheca dendritica).

Much later in the day, we got back in the water for a night snorkel. It was fun, but my dive light went out, and we were all way too close to each other – I think we were all paranoid about losing the group. When I got back, I found a tiny little fish inside my swimsuit. It must have somehow made its way into my skintight dive skin and swimsuit, but nothing can surprise me at this point.

ANGUS crab

Day 3 of Beach Days

Today’s activity definitely took a toll on us — but our Dermit Rab made it all better.

Me and Aungus prior to the start of the race, 3rd and 4th from the right.

We woke up, ate, and swam to the edge of the thousand-feet-drop in the benthos (sea floor). On the way, the supposedly calm waters rocked us to differing degrees of sea sickness. In the water we went in all different directions with regards to the waves, on which we bobbed up and down while we looked in the deeper ocean for interesting life forms. One of the forereefs we explored was geographically filled with canyons of corals. Centuries of wave engergy shaped the current-day grooves filled with hard and soft corals, among other life forms. We observed an especially problematic species of fish, called the lion fish, camouflouging in the corals today. Their presence in this region, which is far from their native rainge, has caused up to 70% decline in native fish populations. Obviously, we speared them and brought them back to dissect, fry, and eat. Which is a prospect even the “vegetarians” are supporting.

In the afternoon, we quanitified the degree of biodiversity of Echinoderms (particularly sea urchins) in a protected and an unprotected marine area. Which means we spent an hour spotting and picking off the spiny sea urchins from dead corals and algae on which they are grazing. While searching for sea urchins, I saw two types of brown algae, specifically, they were two types of white-scrolled algae. One has a darker base and the other a lighter color, but both have a characteristic curly shape that resembles a scroll. In addition, we came into contact with Sargassm seadweed again, which is more or less impossible not to come into contact with due to their prevalence and distribution on the ocean surface. In addition we observed many blister saucer algae, both attached to corals and floating on the surface. Interesting, they too, like the Sargassum, are able to keep some air within their chambered body so that when squished air bubbles are released. Although they do not have a characteristic air bladder like the sea weed, these saucer algae had triangular bulbous organs to hold air.

In the evening, we had one of the best meals we’ve had yet — consisting of flan, spiced chicken, banana bread, lemon cookies, homemade bread, and mashed potato. After our lectures, we collected blue crabs and hermit crabs to race in the sand. Among 5+ competitors, one travelled in the opposite direction, 1 paused, and 2 finished close to each other. It seems like the large hermit crabs are the best for Dermit Rab. Also obvious that blue land crabs are not the best as they walk side ways and are prone to going to dark places to hide. Angus, me and Claire’s contestant, although big, did just that. :/

The communal nap I have been predicting and advocating for — also happened today! Our tiredness has come to an all time high, but with proper rest, i.e. communal naps, we seem to be a very resilient group.


Hi friends,

Today was similar to the previous day in terms of the diving activities, as we redid the patch reef data collection and sea urchin collection on an area outside of the marine protection zone. We then compared the two data sets, analyzed them based on our project hypothesis and came up with a final poster to showcase our results.

My first takeaway of the day was how adorable sea urchins are. After seeing how they move about using their spines, my perception of them changed completely. And having to handle and measure them also made me like them so much more. Just see the picture below to see how close we’ve gotten.

Black sea urchin (Diadema antillarum) on my back!

It was also fun surveying another patch reef area, and after the experience from the previous day, I was much more confident with collecting data and also identifying organisms in general. Below are some of the creatures I managed to capture (with my camera)!

It’s a Christmas Tree Worm (Spirobranchus giganteus)!

There were Christmas tree worms everywhere!!! And I saw a new mollusk species which I have never seen personally, the Cyphoma gibbosum (flamingo tongue shell):

Flamingo tongue (Cyphoma gibbosum) right in the middle

Exciting times. I’m looking forward to the next few days because we will get to check out other reef types such as the backreefs and forereefs, and I’m eager to see how different they will be from path reefs.

After snorkeling, we spent the afternoon analyzing our data and creating our poster to present to Adrienne and Scott. And then right before dinner we had a friendly pickup game with some of the island staff. Got to sweat it all out! I have to say, Alessi is pretty tenacious when it comes to fighting for the ball, and Therese and Isaac are great technical players. Meanwhile, Deepu is definitely the star striker like Cristiano Ronaldo, scoring 2 of the goals for us. This is my brief analysis of EBIO 319’s soccer team.

All in all, today went by really quickly and I thoroughly enjoyed both the snorkeling experience and the free time to mingle with the other people in Middle Caye. Looking forward to more tomorrow!

Till then,


Day 11: Counting corals and urchins

The projects of the day consisted of comparing live stony coral cover and numbers of urchins between the Marine Protected Area (MPA) and a zone outside of the MPA at Glovers Reef. To measure coral cover, we laid down 7 transects that were each 100 ft long. Every 25 ft along the transect we measured two quadrats that were 2 ft by 2 ft. Each quadrat is fitted with twine to make 81 squares, or 64 intersection points. We looked at what was underneath each intersection and classified it as live stony coral, recently dead stony coral, macroalgae, other living organisms, or other dead/abiotic objects. Tomorrow we will analyze the data that we gathered, but we predicted that there would be a higher percent of live coral cover inside the MPA.

To count urchins, we timed how many urchins 18 people could collect in 25 minutes. Tomorrow we will compile all of the data and determine which urchin species were most common and quantify the difference between the MPA and the area outside the MPA.

Collected urchins (Photo credit: Scott)
Collected urchins (Photo credit: Scott)

We didn’t have very much time to explore the reef, but during data collection I was able to observe several species of parrotfish, including what I believe was a stoplight parrotfish. I also noted a large number of flamingo tongue snails, which are an interesting species of mollusk that is mostly an off-white shade with yellow spots that have a black outline. The snails are mostly found on sea fans.

As for green algae, I saw pinecone algae in the MPA. The pinecone algae are concentrated in sandy areas where they are able to attach their holdfast to the sand. The pinecone algae were smaller than I was expecting and were narrower, so they could be a slightly different species than I researched. There was also calcareous green algae that was growing on dead coral both in the MPA and outside of it. While the algae consisted of multiple species, I believe that most of them were species of Halimeda. Most of the green algae that I saw today was covered in sediment so it was difficult to identify the exact species.

Urchin Day + Snorkel Fun

Hi everyone! I saw so many urchins today!! Before I get into those, I’ll give a quick rundown of the day’s activities. Today consisted mainly of two projects: determining the percent coverage of live coral on the reef and collecting sea urchins. This morning we took a boat out to a patch reef in the lagoon and used transects and quadrats to count the number of live coral, recently dead coral, and macroalgae among other things to determine the health of the coral reef. Since sea urchins both help the coral by consuming the algae that live on them and harm the coral by boring into them, we also did a timed sea urchin collection to see how many urchins we could all catch and returned to the island to identify and measure them. In the afternoon, we repeated the morning’s activities outside of the lagoon.

Slate pencil urchins (Eucidaris tribuloides)
Slate pencil urchins (Eucidaris tribuloides)

Now on to the sea urchins!! In the lagoon alone, we collected over a hundred Echinometra viridis (a small brown/red urchin with spines that have a pale ring close to the body). We also found quite a few Eucidaris tribuloides (commonly known as slate pencil urchins, reddish brown body with blunt spines) and some Tripneustes ventricosus (an urchin with a black/dark purple body and short white spines) hiding in the coral crevices in the lagoon.

A long-spined sea urchin (Diadema antillarum)
A long-spined sea urchin (Diadema antillarum)

In the afternnon, we also collected some Diadema antillarum (a long-spined sea urchin whose spines easily penetrate skin) among the coral and a few Meoma ventricosa, both the live and dead versions (a flattened globe urchin with a reddish body and a five petal design on its back) buried in the sand along with the other species. It was interesting to me that we found the long-spined urchins and red heart urchins mainly outside of the lagoon, while inside we mainly were able to find the viridis species.

Several reef urchins (Echinometra viridis)
Several reef urchins (Echinometra viridis)

In other words, it was a very exciting day for me! I absolutely loved getting to find, hold, and work with the urchins more today. 🙂 I can’t wait to see what tomorrow brings and what echinoderms I’ll spot tomorrow. Thanks for reading everybody!