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

David Hall / A Giant rock scallop (Crassadoma gigantea) encrusted with and surrounded by several other invertebrates, including White anemones (Metridium sp.), White mushroom ascidians (Distaplia sp.), Red soft co...

Alex Mustard / A shiver of Caribbean reef sharks (Carcharhinus perezi) swim over a coral reef with Common sea fans (Gorgonia ventalina) and sea plumes (Pseudopterogorgia sp). Jardines de la Reina, Gardens of the Que...

Alex Mustard / A vibrant Caribbean coral reef with two Reef sharks (Carcharhinus perezi) and Common sea fans (Gorgonia ventalina) and sea plumes (Pseudopterogorgia sp). Jardines de la Reina, Gardens of the Queen Nat...

Shane Gross / A Giant clam (Tridacna gigas) surrounded by Lettuce coral (Turbinaria reniformis), Kosrae, Micronesia.

Georgette Douwma / Crinoid (Crinoidea) on Soft coral (Alcyonacea). Derawan Islands, East Kalimantan, Indonesia.

Franco Banfi / Cuckoo wrasse (Labrus mixtus) male in front of Red sea fan, (Paramuricea clavata), Stupiste In dive site, Vis Island, Croatia, Adriatic Sea, Mediterranean

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

Alex Mustard / Split level image of Leather corals (Sarcophyton sp.) flourishing in shallow water close to uninhabited coral islands. Misool, Raja Ampat, West Papua, Indonesia. Ceram Sea. Tropical West Pacific Ocean...

Alex Mustard / Midnight snapper (Macolor macularis) shelters in a cavern on a coral reef with white soft corals (Scleronephthya sp.) and solderfish. Vavuu Atoll, Maldives. Indian Ocean

Jordi Chias / Primnoella soft coral, Antarctic Peninsula, Antarctica.

SCOTLAND: The Big Picture / Orange jewel anemones (Corynactis viridis) Sula Sgeir, Scotland, UK, February.

SCOTLAND: The Big Picture / Dead man's fingers (Alcyonium digitatum) on a rocky reef with view of the sky, Shetland, Scotland, UK, August.

SCOTLAND: The Big Picture / Close up of a colony of Jewel anemones (Corynactis viridis) Scotland, UK, October.

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

Shane Gross / Caribbean reef shark (Carcharhinus perezi) patrolling coral reef with Schoolmaster snapper (Lutjanus apodus) and other fish. Caribbean Sea off Gardens of the Queen National Park, Cuba.

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

David Fleetham / Green sea turtles (Chelonia mydas) on corals, Hawaii.

Alex Mustard / RF - High magnification photo of Secretary blenny (Acanthemblemaria maria) in boulder brain coral (Colpophyllia natans). East End, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea. (Th...

Alex Mustard / Hawksbill turtle (Eretmochelys imbricata) male chomps on soft coral. Jackson Reef, Sinai, Egypt. Strait of Tiran, Red Sea.

Alex Mustard / A stand of Pillar coral (Dendrogyra cylindrus) growing on a coral reef, East End, Grand Cayman, Cayman Islands

Jordi Chias / Spotted catshark (Scyliorhinus canicula) just hatched from egg case that is on Seafan (Paramuricea clavata), Ullastres seamount, Costa Brava, Llafranch, Catalunya, Spain

Alex Mustard / Boulder brain coral (Colpophyllia natans) photographed with a long exposure with camera rotation. Taken with circular fisheye lens. Grand Cayman, Cayman Islands. Caribbean Sea.

Alex Mustard / Colourful reef scene with Leather corals (Sarcophyton sp.), Soft corals (Dendronephthya sp.) Seafans (Melithea sp.) and fish, including Magenta slender anthias (Luzonichthys waitei) and Scalefin anthi...

Franco Banfi / Hard and soft corals and encrusting sponge on the structure of bio-rock, Karang Lestari Pemuteran project, Desa Pemuteran, Bali Island, Indonesia, Pacific Ocean

Franco Banfi / Corals attached to structure of bio-rock, a method of enhancing the growth of corals and aquatic organisms, Karang Lestari Pemuteran project, Desa Pemuteran, Bali Island, Indonesia, Pacific Ocean.

Franco Banfi / Corals attached to structure of bio-rock, a method of enhancing the growth of corals and aquatic organisms, Karang Lestari Pemuteran project, Desa Pemuteran, Bali Island, Indonesia, Pacific Ocean.

Juergen Freund / Gorgonian fan coral (Gorgonaceae) in the shallow mangroves, split level. North Raja Ampat, West Papua, Indonesia. Second Place in the Portfolio Award of the Terre Sauvage Nature Images Awards Competit...

Juergen Freund / Split level view of coral reef, Komodo National Park, Flores, Lesser Sunda Islands, Indonesia. Second Place in the Portfolio Award of the Terre Sauvage Nature Images Awards Competition 2015.

Alex Mustard / Diver exploring the wreck of HMS Scylla, which is colonized by Dead man's fingers (Alcyonium digitatum). Whitsands Bay, Cornwall, England. UK, July.

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.

Alex Mustard / Group of predators hunting together, in an example of 'Nuclear foraging'. The Moray eel (Gymnothorax javanicus) flushes out prey, and is followed by a Napolean wrasse (Cheilinus undulatus) and a Bluef...

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

Juergen Freund / Chambered nautilus (Nautilus pompilius) with red whip coral. Osprey Reef, Great Barrier Reef, Queensland, Australia.

Constantinos Petrinos / Purple short tentacle mushroom coral (Fungia sp.) close up of polyps. Lembeh Strait, North Sulawesi, Indonesia.

Alex Mustard / Close up of tiny (10mm) Pygmy seahorse (Hippocampus bargibanti) living disguised in Muricella sp. sea fan. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Alex Mustard / Busy coral reef community feeding on plankton, with Scalefin anthias (Pseudanthias squamipinnis), Soft corals (Dendronephthya sp.) and Fire corals (Millepora dichotoma), making up classic Red Sea scen...

Alex Mustard / RF- School of Scalefin anthias (Pseudanthias squamipinnis) on reef in the current feeding on plankton, with soft corals (Dendronephthya spp.) and fire coral (Millepora dichotoma) Jackson Reef, Strait...

Alex Mustard / Busy coral reef community feeding on plankton, with Scalefin anthias (Pseudanthias squamipinnis), Soft corals (Dendronephthya sp.) and Fire corals (Millepora dichotoma) Ras Mohammed Marine Park, Sinai...

Alex Mustard / Vibrant Red Sea reef scene, with orange female Scalefin anthias (Pseudanthias squamipinnis) swarming in front of Fire coral (Millepora dichotoma) feeding on plankton brought to the reef by currents. R...

Alex Mustard / Shallow coral reef flat with corals (Pocillopora damicornis, Acropora humilis and Pocillopora verrucosa) in evening light. Gordon Reef, Strait of Tiran, Sinai, Egypt. Gulf of Aqaba, Red Sea.