Ismaele Tortella / Eurasian otter (Lutra lutra) hunting in a shoal of Atlantic herring (Clupea harengus), northern Norway, March

Alex Mustard / Yellowtail tang (Zebrasoma xanthurum) male and female turn belly to belly during spawning to ensure fertilization. Temple, Ras Umm Sid, Sharm El Sheikh, Sinai, Egypt. Red Sea. This action is very fast...

Chase Dekker / Humpback Whale (Megaptera novaeangliae) pod gulp feeding on Northern Anchovy (Engraulis mordax), Monterey Bay, California

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

Alex Mustard / Dugong (Dugong dugon) male and juvenile Golden trevally (Gnathanodon speciosus) swimming over Seagrass (Halophila stipulacea) meadow. Marsa Nabaa, Marsa Alam, Egypt.

Alex Mustard / Green turtle (Chelonia mydas) resting on sea floor and two juvenile Golden trevally (Gnathanodon speciosus). Marsa El Shouna, Marsa Alam, Egypt.

Shane Gross / Flying fish (Exocoetidae) in Sargasso Sea, Atlantic Ocean.

Gary Bell/ Oceanwide / Spotted Wobbegong (Orectolobus maculatus), Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Port Jackson Shark (Heterodontus portusjacksoni), Australia

Gary Bell/ Oceanwide / Grey Nurse Shark (Carcharias taurus), Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Sea Goldie (Pseudanthias squamipinnis) school in coral reef with feather stars, Great Barrier Reef, Queensland, Australia

Gary Bell/ Oceanwide / Yellow-banded Snapper (Lutjanus adetii) school, Heron Island, Great Barrier Reef, Queensland, Australia

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

Gary Bell/ Oceanwide / Black-spot Goatfish (Parupeneus signatus) and Goldlined Seabream (Rhabdosargus sarba) school, Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Blacktip Bullseye (Pempheris affinis) school, Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Stripey (Microcanthus strigatus) school, Coffs Harbor, Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Eastern Pomfred (Schuettea scalaripinnis) school, Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Common Lionfish (Pterois volitans) hunting Basslets (Pseudanthias sp), Christmas Island, Australia

Gary Bell/ Oceanwide / Blackfoot Firefish (Parapterois heterurus) at night, Anilao, Philippines

Gary Bell/ Oceanwide / Zebra Lionfish (Dendrochirus zebra), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning female Stocky Anthias (Pseudanthias hypselosoma), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Fire Goby (Nemateleotris magnifica), Great Barrier Reef, Queensland, Australia

Gary Bell/ Oceanwide / Painted Sweetlips (Diagramma pictum) in Slender Cardinalfish (Rhabdamia gracilis) school, Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Painted Sweetlips (Diagramma pictum) in Slender Cardinalfish (Rhabdamia gracilis) school near Double-headed Maori Wrasse (Cheilinus undulatus), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Whitemouth Moray (Gymnothorax meleagris) being cleaned by Cleaner Wrasse (Labroides sp) juvenile, Christmas Island, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning Yellow-edged Moray (Gymnothorax flavimarginatus), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning Honeycomb Moray Eel (Gymnothorax favagineus), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Variegated Jawfish (Opistognathus solorensis) male brooding eggs in mouth, Anilao, Philippines

Gary Bell/ Oceanwide / Variegated Jawfish (Opistognathus solorensis) male brooding eggs in mouth, Anilao, Philippines

Gary Bell/ Oceanwide / Double-headed Maori Wrasse (Cheilinus undulatus), Painted Sweetlips (Diagramma pictum), and Slender Cardinalfish (Rhabdamia gracilis) school, Great Barrier Reef, Queensland, Australia

Gary Bell/ Oceanwide / Leopard Flounder (Bothus pantherinus) camouflaged on ocean floor, Anilao, Philippines

Gary Bell/ Oceanwide / Oriental Flying Gurnard (Dactyloptena orientalis) with pectoral fins extended in defense posture, Anilao, Philippines

Gary Bell/ Oceanwide / Sole (Zebrias sp) juvenile, Anilao, Philippines

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Goldbelly Cardinalfish (Apogon apogonides), Tulamben, Bali, Indonesia

Jordi Chias / Humped rockcod (Gobionotothen gibberiformis), Antarctic Peninsula, Antarctica.

Jordi Chias / Black rockcod (Notothenia coriiceps), Antarctic Peninsula, Antarctica.

Jordi Chias / Crocodile icefish or White-blooded fish (Channichthyidae), Antarctic Peninsula, Antarctica.

Jordi Chias / Rock cod (Notothenia) Antarctic Peninsula, Antarctica.

Jordi Chias / Black rockcod (Notothenia coriiceps), Antarctic Peninsula, Antarctica.

Alex Mustard / Three Pink anemonefish (Amphiprion perideraion) living in a purple skirted magnificent sea anemone (Heteractis magnifica) on a coral reef, below a small island. Misool, Raja Ampat, West Papua, Indones...

Alex Mustard / Whale shark (Rhincodon typus) close to the camera with a golden trevally fish (Gnathanodon speciosus) and outline of another whale shark behind , in the plankton-rich green waters of La Paz bay, Baja...

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

Alex Mustard / School of White collar butterflyfish (Chaetodon collare) pack together above a coral reef. North Male Atoll, Maldives. Indian Ocean

Alex Mustard / Orange painted frogfish (Antennarius pictus) fishing. Here the frogfish is illuminated by a snooted strobe and the background sand lit with a red LED torch. Bitung, North Sulawesi, Indonesia. Lembeh S...

Alex Mustard / Thorny seahorse (Hippocampus histrix) gripping onto a sponge. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Alex Mustard / Pair of Western clown anemonefish (Amphiprion ocellaris) spawning orange eggs on the rock beneath their Magnificent sea anemone (Heteractis magnifica) home on a coral reef. This photo shows the larger...

Alex Mustard / Two female Common seahorses (Hippocampus kuda) fighting over territory on the seabed. The brief fight was preceeded by a ritualised, synchronised parade. Bitung, North Sulawesi, Indonesia. Lembeh Stra...

Alex Mustard / Common seahorse (Hippocampus kuda) female wrapping her prehensile tail around piece of wood on the seabed. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Alex Mustard / Whitemargin stargazer (Uranoscopus sulphureus) sets an ambush in the sand at night. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Alex Mustard / Reef lizardifsh (Synodus variegatus) at a cleaning station, being cleaned by Holthuis anemone shrimps (Ancylomenes holthuisi). Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Tony Wu / Fringed blenny (Chirolophis japonicus) guarding its eggs. Miyagi Prefecture, Japan.

Tony Wu / View down the throat of a male Zoarchias major eelpout (Zoarchias major) that has opened its mouth during a confrontation with another male. Yamaguchi Prefecture, Japan. Pacific Ocean.

Tony Wu / Two male Zoarchias major eelpouts (Zoarchias major) engaged in a mouth-to-mouth confrontation. Yamaguchi Prefecture, Japan, Pacific Ocean.

Tony Wu / Zoarchias major eelpouts. (Zoarchias major) The orange individual is female, the one in the hole is male. The female has approached the male, curled around him, attempting to dislodge the male from th...

Tony Wu / Zoarchias major eelpout (Zoarchias major) with her mouth wide open. Yamaguchi Prefecture, Japan, Pacific Ocean.

Tony Wu / Sardines (Clupeidae) fleeing from predators in the early morning. They were being herded and chased by Trevallies and Blacktip reef sharks in the water, and picked off by brown boobies and terns from...

Alex Mustard / RF - Denise's pygmy seahorse (Hippocampus denise) looks out from its home in a sea fan (Annella sp.). Misool, Raja Ampat, West Papua, Indonesia. Ceram Sea. Tropical West Pacific Ocean. (This image...

Alex Mustard / Portrait of a tarpon (Megalops atlanticus) on a coral reef. East End, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea.

Alex Mustard / Portrait of a male short snouted seahorse (Hippocampus hippocampus) in sea oak seaweed (Halidrys siliquosa). Devon, England, United Kingdom. British Isles. English Channel. North East Atlantic Ocean.

Alex Mustard / Forster's hawkfish (Paracirrhites forsteri) on a coral reef. Jackson Reef, Tiran, Sinai, Egypt. Strait of Tiran, Gulf of Aqaba, Egypt.

Ralph Pace / Shortfin Mako (Isurus oxyrhynchus) male caught on fishing line, California

Shane Gross / Larval flounder (possibly Laeops Kitahara) in the open ocean at night off Anilao, Philippines.

Shane Gross / Portrait of a Thorny seahorse (Hippocampus histrix) near Malapascua, Philippines.

Shane Gross / Pygmy seahorse (Hippocampus bargibanti) holding on to a branch of a sea fan coral. Malapascua, Philippines.

Shane Gross / Pelagic thresher shark (Alopias pelagicus) cleaned by a Bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.

Shane Gross / Pelagic thresher shark (Alopias pelagicus) being cleaned by a bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.

Shane Gross / Thorny or spiny seahorse (Hippocampus histrix) portrait made off Anilao, Philippines.

Shane Gross / Almaco jack (Seriola rivoliana) uses a discarded fishing net, drifting in the open ocean as shelter. The Bahamas.

Shane Gross / Graysby fish (Cephalopholis cruentata) a type of grouper, hiding in a sponge off Eleuthera, Bahamas.

Shane Gross / Moorish idol (Zanclus cornutus) juvenile with transparent skin in the open ocean at night off Anilao, Philippines.

Shane Gross / A juvenile soldierfish, possibly a Crescent-tail bigeye (Priacanthus hamrur) in the open ocean at night off Anilao, Philippines.

Espen Bergersen / Herring (Clupea harengus) caught in fishing net. Gulls in the net are taking of and flying around, shot with long shutter speed. Norway. December. November

Georgette Douwma / Shortfin lionfish (Dendrochirus brachypterus). Lembeh Strait, North Sulawesi, Indonesia.

Georgette Douwma / Ribbon eel ( Rhinomuraena quaesita) Lembeh Strait, North Sulawesi, Indonesia.

Georgette Douwma / Banggai cardinalfish (Pterapogon kauderni) with a Corkscrew or Long tentacle anemone (Macrodactyla doreensis). Lembeh Strait, North Sulawesi, Indonesia.

Georgette Douwma / Thornback cowfish (Lactoria fornasini). Lembeh Strait, North Sulawesi, Indonesia.

Georgette Douwma / Taylor's pygmy leatherjacket (Brachaluteres taylori). Lembeh Strait, North Sulawesi, Indonesia.

Nick Hawkins / Juvenile Pollock (Pollachius virens) school within the protective fronds of kelp near Port Joli, Nova Scotia, Canada. August

Nick Hawkins / Atlantic salmon (Salmon salar) under river ice. Quebec, Canada. October.

Nick Hawkins / Chum salmon (Oncorhynchus keta) migrate up a small river near Bella Bella, British Columbia, Canada. September

Nick Hawkins / Ocean sunfish (Mola mola) off Halifax, Nova Scotia, Canada. July.

Nick Hawkins / Blue shark (Prionace glauca) with a pair of pilot fish (Naucrates ductor) off Halifax, Nova Scotia, Canada. July.

Nick Hawkins / Atlantic bluefin tuna (Thunnus thynnus) off Antigonish, Nova Scotia, Canada. October .

John Chan / California sea lion (Zalophus californianus) feeding on a Striped bass (Morone saxatilis), Southern California, USA.

SCOTLAND: The Big Picture / Cuckoo wrasse (Labrus bergylta) and Ballan wrasse (Labrus bergylta) on the wreck of Jayne, Shetland

Espen Bergersen / Aerial shot of a fishing boat catching Atlantic herring (Clupea harenguis), with Killer whales (Orcinus orca) and Humpback whales (Megaptera novaeangliae) swimming around the boat and large numbers of...

Espen Bergersen / Aerial shot of a fishing boat catching Atlantic herring (Clupea harenguis), with Killer whales (Orcinus orca) and Humpback whales (Megaptera novaeangliae) swimming around the boats and large numbers o...

Espen Bergersen / Aerial shot of fishing boats catching Atlantic herring (Clupea harenguis), with Killer whales (Orcinus orca) swimming around the boats, Troms, Norway, January.

Espen Bergersen / Aerial shot of two Killer whales (Orcinus orca) swimming inside a shoal of Atlantic herring (Clupea harenguis), hunting, with one Killer whale tail slapping to stun the Herring, Sommaroy, Troms, Norwa...

Espen Bergersen / Aerial shot of two Killer whales (Orcinus orca) swimming into a huge shoal of Atlantic herring (Clupea harenguis), hunting, Sommaroy, Troms, Norway, January.

Espen Bergersen / Aerial shot of two Killer whales (Orcinus orca) swimming near to a huge shoal of Atlantic herring (Clupea harenguis), hunting, Sommaroy, Troms, Norway, January.

Espen Bergersen / Aerial shot of two Killer whales (Orcinus orca) swimming inside a shoal of Atlantic herring (Clupea harenguis), hunting, Sommaroy, Troms, Norway, January.

Espen Bergersen / Aerial shot of two Killer whales (Orcinus orca) swimming inside a large shoal of Atlantic herring (Clupea harenguis), hunting, Sommaroy, Troms, Norway, January.

Espen Bergersen / Aerial shot of a huge shoal of Atlantic herring (Clupea harenguis), with a Humpback whale (Megaptera novaeangliae) nearby, Sommaroy, Troms. Norway, January.

Espen Bergersen / Aerial shot of Killer whale (Orcinus orca) hunting Atlantic herring (Clupea harengus), Troms, Norway, October.