Today was another activity filled day of snorkel work using our quadrants to evaluate density of corals in two different areas as well as finding sea urchins as a proxy of coral density. While not directly related to each other, differing ratios of coral to algae ratio can affect urchin diversity and abundance. One cool thing to know about sea urchins is that they feed primarily on algae that compete with corals. In a way, the urchins keep the algae from taking over the coral spaces. The data obtained from this project could give us a clue as to how these reefs are doing, given their tragic demise these recent years.
During our search, I encountered 2 little jelly blobs that were virtually transparent in the water. The only way to see them was to see how the light was bent differently due to passing through a jelly medium. These guys were about the size of a golf ball and looked quite fragile. I wonder if they were the ctenophores I am looking for. Ctenophores are also known as comb jellies referencing their comb like cilia hairs that they use to swim through the waters. Comb jellies actually aren’t jellyfish in the true sense. Genetically, their more related to sponges than to true jellyfish. They also have a fundamentally different body structure than jellyfish, having a lobed appearance and no stinging tentacles.
I couldn’t see if these little jelly blobs were actually ctenophores. This makes me wonder about the frustration of professionals who study these jellies.
Other than those two jellies, I went back this evening to snap some photos of those upside down jellies from a few days ago. Based on the images, I can say with confidence that they are Cassiopea frondosa. A similar upside down jellyfish, C. xamachana, has leaf-like projections sticking from its tentacles, which picture doesn’t show.