Bubble Coral

Plerogyra sinuosa, commonly known as bubble coral, is a jelly-like species belonging to the phylum Cnidaria. This species is characterized by its bubbly appearance, with grape-sized bubbles that vary in size based on the amount of light available. During the day, the bubbles are larger, while they become smaller at night when the coral extends its tentacles to capture food. Bubble coral requires low light and gentle water flow to thrive.

Also known as grape coral, bladder coral, and pearl coral, Plerogyra sinuosa is found in a vast geographical range, spanning from the 🌊 Red Sea and 🇲🇬 Madagascar in the western 🌊 Indian Ocean to Okinawa (🇯🇵 Japan) and the Line Islands in the Pacific, as documented by the International Union for Conservation of Nature (IUCN).

The colonies of Plerogyra sinuosa take the shape of an inverted cone, reaching up to a meter in diameter. In smaller colonies, the corallites are monocentric and trochoid, while larger colonies exhibit a flabellomeandroiid arrangement, with valleys and separate walls. The septa, which are the internal structures of the coral, have smooth margins and irregular arrangement. Young colonies may display lobes formed by costae, which later develop spines. This unique budding method is uncommon among corals.

When alive, Plerogyra sinuosa possesses vesicles that resemble bubbles and can grow up to 2.5 cm in diameter. These vesicles expand during the day to expose the polyps and their tentacles, but retract to some extent at night.

Plerogyra sinuosa is a zooxanthellate coral species, meaning it relies on symbiotic dinoflagellates that reside within its soft tissues, including the vesicle walls. These photosynthetic organisms supply the coral with organic carbon and nitrogen, meeting up to 90% of the coral's energy requirements for metabolism and growth. The remaining nutritional needs of Plerogyra sinuosa are fulfilled by the planktonic organisms captured by its polyps.