May 25, 2019
Today was a big day for Scyphozoa and Ctenophores, otherwise known as true jellyfish and comb jellies respectively. When we unloaded at one of our experiment locations, we had to quickly get back into the boat when we realized Moon Jellies (Aurelia aurita) were everywhere (they can deliver a painful sting), but that doesn’t mean I didn’t take a picture first.
There were also a lot of comb jellies (unknown species). These jellies look similar to jellyfish but are actually from a completely different phylum and use sticky cells called colloblasts to catch prey rather than stinging cells like jellyfish. This is why Amanda was able to safely hold one in her hand.
Eventually, our marine safety officer Herbie found a reef that wasn’t infested with jellyfish. While he was checking the area, he said he saw lots of squid and lionfish. I didn’t end up finding any squid myself, but I did get to watch Herbie spear one of the lionfish – they’re invasive to the Caribbean and eat a lot of important herbivorous fish populations.
Later, we went to the forereef, which was much deeper than the patch reefs inside the atoll. I got to see some living elkhorn coral (Acropora palmata), a nurse shark, several southern sting rays, and a very linear group of small squid.
I lie on my back on the hammock, swaying gently side-to-side in the breeze. My eyelids float down after a busy morning and afternoon. I witness deep oranges and rusty reds shifting, bursting, and intertwining on the backs of my eyelids, luminescent projections of the intense tropical sunlight. Needless to say, these entrancing visions were enough to lull me to sleep.
This morning I felt quite different – energized and adventurous. Soon after breakfast, my classmates and I measured the sizes of the urchins we caught yesterday at the Marine Protected Area (MPA). We then snorkeled at a non-MPA and carefully collected urchins there. Interestingly, the urchins tended to be larger and more numerous at the MPA. However, the non-MPA was home to the largest urchin we found, a long spine sea urchin (Diadema antillarum) that measured 5.8 cm in diameter.
With its mounds of different corals, the reef visited today was teeming with a plethora of diverse colorful creatures. Some notable sightings included a green sea urchin (Lytechinus variegatus), spiny brittle stars (Ophiocoma paucigranulata), and numerous ctenophores. The green sea urchin was about 4 inches in diameter and found on the seafloor. The spiny brittle stars, found under rubble, had central disks of about an inch in diameter and arms about 3 inches long. The brittle stars would try to move back under the rubble when exposed. None of the echinoderms were visibly interacting with other organisms. Today’s most spectacular sighting was a spotted trunkfish (Lactophyrus bicaudalis); its dynamic black and white speckles contrasted with the mellow blue backdrop of the ocean.
After spending the afternoon discussing my class’ data collected and observations noted, I was exhausted. We had an hour until dinner, so I lied on my back on the hammock.