David Fleetham / Hawksbill Turtle (Eretmochelys imbricata) and a shoal of fish near sea surface. Tubbataha Reef, Philippines.

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

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

Alex Mustard / Spinner dolphin (Stenella longirostris) pod socialising close to surface. Fury Shoal, Sataya Reef, Marsa Alam, Egypt.

Alex Mustard / Shoal of three Bigfin reef squid (Sepioteuthis lessoniana) in open water at night. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

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.

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.