Shane Gross / Elkhorn corals (Acropora palmata) at night silhouetted by a scientist's light during the annual coral spawn. Abaco, Bahamas.

Juergen Freund / Bleached Staghorn corals (Acropora cervicornis), Great Barrier Reef, Australia, 2017.

Jordi Chias / Wave breaking over the reef, Table coral (Acropora) Safaga, Egypt, Red Sea.

Alex Mustard / Scissortail sergeants (Abudefduf sexfasciatus) swimming over hard corals (Acropora sp.) on shallow reef at sunset, split level view. Gubal Island, Egypt. Red Sea.

Georgette Douwma / Coral line nursery with Acropora corals grown to reintroduce to the Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Floris van Breugel / Staghorn corals (Acropora) on the coast of tropical island Ofu, one of the Manu'a islands, American Samoa. 2012.

Chris Newbert / Stony Coral (Acropora sp) and baitfish, Solomon Islands

Fred Bavendam / Stony Coral (Acropora sp) colony releasing egg-sperm bundles during the mass coral spawning each March at Ningaloo Reef, Western Australia

Fred Bavendam / Staghorn Coral (Acropora cervicornis) colony releasing egg-sperm bundles during the mass coral spawning each March at Ningaloo Reef, Western Australia

Fred Bavendam / Stony Coral (Acropora sp) colony releasing egg-sperm bundles during the annual mass coral spawning on the Great Barrier Reef, Queensland, Australia

Fred Bavendam / Staghorn Coral (Acropora cervicornis) colony with an extensive bleached area at its center, Kimbe Bay, Papua New Guinea

Alex Mustard / Hard corals (including Acropora sp., Platygyra sp. and Pocillopora spp.) growing in shallow water and reflected in the surface. Ras Umm Sid, Sharm El Sheikh, Sinai, Egypt. Red Sea