Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

David Fleetham / Cleaner wrasse (Labroides dimidiatus) swimming alongside Golden damsel (Amblyglyphidodon aureus) looking for parasites, Fiji, Pacific Ocean.

Alex Mustard / Colourful reef scene with Coral grouper (Cephalopholis miniata), map puffer (Arothron mappa) and Panda butterflyfish (Chaetodon adiergastos). Tank Reef, Fiabacet Islands, Misool, Raja Ampat, Indonesia...

Georgette Douwma / White banded/ Scarlet cleaner shrimp (Lysmata amboinensis) on Coral hind (Cephalopholis miniata) Rinca, Komodo National Park, Indonesia, October

Georgette Douwma / Coral hind (Cephalopholis miniata) lying in ambush under table coral on reef. Andaman Sea, Thailand.

Jeff Rotman / Close-up of the eye of a Jewel Grouper / Coral hind (Cephalopholis Miniata) Red Sea, Egypt

Jeff Rotman / Jewel Grouper / Coral hind (Cephalopholis Miniata) with mouth open, Red Sea, Egypt

Georgette Douwma / Coral hind (Cephalopholis miniata) lying in ambush amongst soft corals. Andaman Sea, Thailand.

Norbert Wu / Coral Grouper (Cephalopholis miniata) changes color to match surroundings and mood, Red Sea, Egypt

Fred Bavendam / Coral Grouper (Cephalopholis miniata), Andaman Sea, Thailand

Norbert Wu / Coral Grouper (Cephalopholis miniata) a type of grouper, changes color at will, Great Barrier Reef, Australia