Tony Wu / Humphead parrotfish (Bolbometopon muricatum) shoal spawning in early morning, part of mass aggregation of thousands of fish. Caroline Islands, Palau.

Alex Mustard / Male Bullethead parrotfish (Chlorurus sordidus) displaying in late afternoon. Ras Katy, Sinai, Egypt. Gulf of Aqaba, Red Sea.

Jeff Rotman / Close up of mouth of a Stoplight parrotfish (Sparisoma viride) Bahamas, Caribbean

Jeff Rotman / Bullethead parrotfish (Chlororus sordidus) tail. Red Sea, Egypt

Shane Gross / Stoplight parrotfish (Sparisoma viride) eating algae on coral reef. Eleuthera, Bahamas.

David Fleetham / Bumphead parrotfish (Bolbometopon muricatum), Yap, Micronesia.

Linda Pitkin / Stoplight parrotfish (Sparisoma viride), male, biting coral rock (feeding on encrusting algae) Bonaire, Leeward Antilles, Caribbean.

Alex Mustard / Bullethead parrotfish (Chlorurus sordidus) male, close up of eye, whilst sleeping at night. The Alternatives, Sinai, Egypt. Red Sea

Georgette Douwma / Greenthroat or Singapore parrotfish (Scarus prasiognathos), terminal male grazing on algae covered coral boulder, Andaman Sea, Thailand. December.

Alex Mustard / Bumphead parrotfish (Bolbometopon muricatum) gather at dawn on a shallow coral reef. Sipadan Island, Sabah, Borneo, Malaysia. Celebes Sea. Vulnerable species.

Pete Oxford / Stoplight parrotfish (Sparisoma viride) on coral reef, Hol Chan Marine Reserve, Belize.

Georgette Douwma / Greenthroat or Singapore parrotfish (Scarus prasiognathus), large school of terminal males grazing on algae covered coral boulders. Andaman Sea, Thailand.

Georgette Douwma / Greenthroat or Singapore parrotfish (Scarus prasiognathus), grazing on a granite boulder, with a small Remora (Echeneis naucrates) attached. Andaman Sea, Thailand.

Alex Mustard / Portrait of a female Stoplight parrotfish (Sparisoma viride) hovering above a coral reef. Bucaneer Reef, Cayman Brac, Cayman Islands. Caribbean Sea.

Georgette Douwma / Stoplight parrotfish (Sparisoma viride), super male (will always remain male), terminal phase. Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stoplight parrotfish (Sparisoma viride) terminal phase. Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stoplight parrotfish (Sparisoma viride) initial phase. Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stoplight parrotfish (Sparisoma viride) initial phase. Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stoplight parrotfish (Sparisoma viride) initial phase turning into terminal phase. Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stoplight parrotfish (Sparisoma viride), terminal phase, super male. Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stoplight parrotfish (Sparisoma viride), terminal phase, grazing on coral rock, shadowed by a Trumpetfish (Aulostomus maculatus) next to a Rocky beauty (Holacanthus tricolor) Bonaire, Netherlands Ant...

Georgette Douwma / Stoplight parrotfish (Sparisoma viride) terminal phase. Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stoplight parrotfish (Sparisoma viride) initial phase. Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stoplight parrotfish (Sparisoma viride) terminal phase. Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Juergen Freund / Bumphead parrotfish (Bolbometopon muricatum) shoal. Sipadan Island, Sabah, Borneo.

Pete Oxford / Parrotfish (Scaridae) for sale, Suva Seafood Market, Viti Levu, Fiji, South Pacific, April 2014.

Pascal Kobeh / Group of Humphead parrotfish (Bolbometopon muricatum) swimming above coral reef, Sudan. Red Sea.

Pascal Kobeh / Two Humphead parrotfish (Bolbometopon muricatum) swimming on above coral reef, Sudan. Red Sea.

Pascal Kobeh / Humphead parrotfish (Bolbometopon muricatum) above coral reef, cleaned by two Blue streaked cleaner wrasses (Labroides dimidiatus) among Jewel fairy basslets / anthias (Pseudanthias squamipinnis) Suda...

Pascal Kobeh / Humphead parrotfish (Bolbometopon muricatum) swimming in open water, Sudan. Red Sea.

Pascal Kobeh / Group of Humphead parrotfish (Bolbometopon muricatum) swimming by coral drop off with divers in the background, Sudan. Red Sea. June 2013.

Pascal Kobeh / Rusty parrotfish (Scarus ferrugineus) close up of tail, coast of Dhofar and Hallaniyat islands, Oman. Arabian Sea.

Pascal Kobeh / Close-up of the head of Bullethead parrotfish (Chlorurus sordidus) sleeping at night in its mucus cocoon, Great Barrier Reef, Australia. Coral sea.

Pascal Kobeh / Close-up of the head of a Bullethead parrotfish (Chlorurus sordidus) sleeping at night, Great Barrier Reef, Australia. Coral sea.

Alex Mustard / The detail of an eye of Bullethead parotfish (Chlorurus sordidus) taken at night. Gubal Barge Wreck, Gubal Island, Egypt. Strait Of Gubal, Egypt.

Chris Newbert / Parrotfish (Scarus sp) fin detail, Red Sea, Egypt

Chris Newbert / Parrotfish (Scarus sp) close-up of eye, Red Sea, Egypt

Chris Newbert / Dark-capped Parrotfish (Scarus oviceps) pectoral fin detail, Solomon Islands

Joel Sartore / Photo Ark / Quoy's parrotfish (Scarus quoyi) head portrait, Omaha's Henry Doorly Zoo & Aquarium. Captive, occurs in western Pacific Ocean.

Joel Sartore / Photo Ark / Quoy's parrotfish (Scarus quoyi) portrait, Omaha's Henry Doorly Zoo & Aquarium. Captive, occurs in western Pacific Ocean.

Joel Sartore / Photo Ark / Quoy's parrotfish (Scarus quoyi) portrait, Omaha's Henry Doorly Zoo & Aquarium. Captive, occurs in western Pacific Ocean.

Joel Sartore / Photo Ark / Quoy's parrotfish (Scarus quoyi) dorsal fin detail, Omaha's Henry Doorly Zoo & Aquarium. Captive, occurs in western Pacific Ocean.

Joel Sartore / Photo Ark / Gulf parrotfish (Scarus persicus) portrait, Sharjah Aquarium UAE. Captive.

Joel Sartore / Photo Ark / Gulf parrotfish (Scarus persicus) portrait, Sharjah Aquarium UAE. Captive.

Alex Mustard / Green-face parrotfish (Scarus prasiognathos) shoal working together to invade the feeding ground of Lined surgeonfish (Acanthurus lineatus) on a coral reef, Raja Ampat, West Papua, Ceram Sea, Pacific...

David Fleetham / Stareye parrotfish (Calotomus carolinus) terminal phase male, swimming over reef, Hawaii, Pacific Ocean.

Doug Perrine / Green sea turtle (Chelonia mydas) being cleaned of algae by Yellow tangs (Zebrasoma flavescens), Chevron tangs (Ctenochaetus hawaiiensis), Black durgon triggerfish (Melichthys niger) and Parrotfish (S...

Russell Laman / Reef manta (Mobula alfredi) getting cleaned of parasites, dead skin, bacteria, and mucus by Blacklip butterflyfish (Chaetodon kleinii) and Moon wrasse (Thalassoma lunare) at a cleaning station in Raja...

Lucas Bustamante / Bumphead parrotfish (Bolbometopon muricatum) and King angelfish (Holacanthus passer) swimming over reef, Gordon Rocks, Galapagos National Park, Pacific Ocean.

Alex Mustard / Roundhead parrotfish (Chlorurus strongycephalus) portrait, South Ari Atoll, Maldives, Indian Ocean.

Alex Mustard / Red Sea steephead parrotfish (Chlorurus gibbus) male, portrait, Ras Mohammed National Park, Sinai, Egypt, Red Sea.

David Fleetham / Bumphead parrotfish (Bolbometopon muricatum) grinding coral / feeding off Sipadan Island, Malaysia, Celebes Sea, Pacific Ocean.

Alex Mustard / Male Bullethead parrotfish (Chlorurus sordidus) fin detail, Sharm El Sheikh, Egypt, Red Sea.

Alex Mustard / Male Bullethead parrotfish (Chlorurus sordidus) eye detail, Sharm El Sheikh, Egypt, Red Sea.

Alex Mustard / Two male Bullethead parrotfish (Chlorurus sordidus), one with a Cave cleaner shrimp (Urocaridella sp) on its nose, sleeping in crevices in a coral reef at night. Sharm El Sheikh, Egypt, Red Sea.

Alex Mustard / Male Bullethead parrotfish (Chlorurus sordidus) with a Cave cleaner shrimp (Urocaridella sp.) on its head, sleeping in a crevice in a coral reef, at night, Sharm El Sheikh, Egypt, Red Sea.

Georgette Douwma / Tropical reef fish composite image on black background, Kasmira snapper (Lutjanus kasmira), Greenthroat parrotfish (Scarus prasiognathos), Two spot wrasse (Oxycheilinus bimaculatus), Rusty parrotfish...

Georgette Douwma / Blue tropical reef fish composite image on black background, Blue triggerfish (Pseudobalistes fuscus), Bicolour angelfish (Centropyge bicolor), Elongate surgeonfish (Acanthurus mata), Yellowtail tang...

Georgette Douwma / Two Stoplight parrotfish (Sparisoma viride), showing terminal phase and initial phase variations, composite image on black background, Bonaire, Netherlands Antilles, Caribbean.

Georgette Douwma / Greenthroat / Singapore parrotfish (Scarus prasiognathos), male and two females, composite image on black background, Andaman Sea, Thailand,

Henley Spiers / Humphead parrotfish (Bolbometopon muricatum) showing breeding colouration, spawning in the early morning, Palau, Micronesia, Pacific Ocean.

Pascal Kobeh / Bullethead parrotfish (Chlorurus sordidus) sleeping at night in its mucus cocoon, Red Sea, Egypt.

Pascal Kobeh / Stoplight parrotfish (Sparisoma viride) sleeping at night, The Gardens of the Queen, Cuba, Caribbean Sea.

Solvin Zankl / Stoplight parrotfish (Sparisoma viride) swimming towards reef and feeding on coral, Bonaire, Leeward Antilles, Caribbean.

Alex Mustard / Colourful coral reef wall, with orange scalefin anthias (Pseudanthias squamipinnis) swarming over red, orange and pink soft corals (Dendronephthya sp.) in a current, with a lone bullethead parrotfish...