Endangered Stag Horn Coral Colony Aroa Lagoonarium Marine Reserve "Raui" directly in front of The Rarotongan Beach Resort & Spa and Sanctuary Rarotonga. There are 368 known Acropora species currently known and come in all kinds of shapes, sizes and colours. Corals have a symbiotic relationship with algae called zooxanthellae that live inside the tissue of the coral and provide the coral with food while the coral provides shelter and access to sunlight. Staghorn coral reproduces either asexually through a piece breaks off and establishes a new colony or sexually by releasing eggs and sperm into the water once a year in August / September. Staghorn corals are listed on Appendix II of the Convention on International Trade in Endangered Species (CITES).