Alex Mustard / Grooved brain coral (Diploria labyrinthiformis) at night with polyps extended to feed, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea.

Alex Mustard / Boulder star coral (Montastrea annularis) photographed under blue light to excite the fluorescence, Little Cayman, Cayman Islands. British West Indies, Caribbean Sea.

Alex Mustard / Boulder star coral (Montastrea annularis) photographed under blue light to excite the green fluorescence, Little Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Alex Mustard / Brain coral (Colpophyllia natans) showing healthy coral, unmanipulated image. East End, Grand Cayman, Cayman Islands. British West Indies. Caribbean Sea.

Alex Mustard / Great star coral (Montastrea cavernosa) male releasing clouds of sperm into the water column, during its synchronised annual spawning event, several hours after sunset in late summer, East End, Grand...

Alex Mustard / Boulder star coral (Montastrea annularis) colony spawning at night in late summer, showing the start of synchronised release of bundles of eggs and sperm from the polyps of the coral, East End, Grand...

Juergen Freund / Jellyfish with symbiotic fishes (Rhizostoma pulmo) Mediterranean