Big barrel sponge

A massive barrel sponge sits among corals suffering from coral bleaching near buoy #2, West Flower Garden Bank. Coral bleaching was the worst on record in 2016: the white corals here are stressed, having suffered from prolonged, elevated water temperatures, and have expelled their symbiotic algae. The algae provides the color to the coral tissues, and it also provides the coral polyps with food by way of photosynthesis. Once the algae has left the coral tissue, the stark white calcium carbonate skeleton is visible through the transparent coral tissue, giving it a "bleached" appearance. If the water temperatures stay too high for too long, and the corals do not re-recruit their algae, the corals may starve and die. Fortunately this was not the case here. The water temperature has decreased, and the corals have been able to re-recruit their symbiotic algae and recover. Another interesting feature visible in this area is the large amount of algae in the sand flat, which could also be a result of 2016's warm water conditions.