The Bubble Coral (Plerogyra sinuosa) is a marine (saltwater) zooxanthellate coral in the Caryophylliidae family of stony corals, although this is not definitive according to some zoologists – they refer to its classification as Incertae sedis or Problematica (which means ‘uncertain placement’ or ‘problematic’). It is in the Cnidaria phylum. It is also known as Grape Coral, Pearl Coral, and Bladder Coral.
The Bubble Coral ‘bubble’ is grape-sized and roundish. It is cream to yellowish to light beige. Bunched together, like grapes, they form a colony that looks like an inverted cone.
The individual ‘bubble’ – called a polyp or vesicle – is larger during the day, and fluctuates in size according to the amount of light available, but on average it is up to 2.5 centimetres (one inch) in diameter. The colony can be 100 centimetres (39 inches) across.
It is common in the Red Sea and south to Madagascar in the Indian Ocean. It prefers areas of gently flowing water with low light.
It is nocturnal, because it feeds at night. Tentacles reach out to catch food floating in the ocean waters.
Location of photographs: Tbilisi Zoo, Georgia
Photographer: Martina Nicolls
Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM