Magnus Lundgren / Juvenile Ocellaris / Common clownfish (Amphiprion ocellaris) looking out from its home in an anemone, Raja Ampat, West Papua, Indonesia, Pacific Ocean.

Magnus Lundgren / School of Yellow-ribbon sweetlips (Plectorhinchus polytaenia) swimming with the current, Raja Ampat, Indonesia, Pacific Ocean.

Henley Spiers / Striped marlin (Kajikia audax) striking a shoal of baitfish during the largest known seasonal aggregation of Marlin, Magdalena Bay, Baja California Sur, Mexico, Pacific Ocean. November 2019

Henley Spiers / Striped marlin (Kajikia audax) and California sea lion (Zalophus californianus) competing for food as they hunt down baitfish, Magdalena Bay, Baja California Sur, Mexico, Pacific Ocean.

Alex Mustard / RF - Portrait of Spinecheek anemonefish (Premnas biaculeatus) in its host Bubble-tip anemone (Entacmaea quadricolor) on a coral reef. Raja Ampat, West Papua, Indonesia. Ceram Sea. (This image may be l...

Alex Mustard / Portrait of a Red Sea anemonefish (Amphiprion bicinctus) above the tentacles of a Magnificent sea anemone (Heteractis magnifica) on a coral reef. Daedelus Reef. Egypt. Red Sea.

David Fleetham / Endangered Green sea turtle (Chelonia mydas) stretches neck to be cleaned by Yellow tangs (Zebrasoma flavescens) and Goldring tangs (Ctenochaetus strigosus), North Pacific, Hawaii, USA.

Doug Perrine / Blue marlin (Makaira nigricans) Vava'u, Kingdom of Tonga, South Pacific

Franco Banfi / Loggerhead turtle (Caretta caretta) accompanied by pilotfish (Naucrates ductor) swimming near the surface. Vulnerable. Santa Maria Island, Azores, Portugal, Atlantic Ocean

Shane Gross / Dugong (Dugong dugon) male and juvenile Golden trevally (Gnathanodon speciosus) shoal swimming over Turtlegrass (Halophila stipulacea) seagrass bed. Marsa Alam, Egypt.

Shane Gross / Cunner (Tautogolabrus adspersus) pair in Eelgrass (Zostera marina) bed. Newfoundland, Canada. September.

David Fleetham / Close up at the dental plates of Three color parrotfish (Scarus tricolor) as it comes in for a bite of hard coral, Fiji.

Terry Whittaker / Brown trout (Salmo trutta) leaping up waterfall to reach spawning grounds upstream. River Endrick, Loch Lomond and The Trossachs National Park, Scotland, UK. July.

Terry Whittaker / Atlantic salmon (Salmo salar) leaping up waterfall to reach spawning grounds upstream. River Endrick, Loch Lomond and The Trossachs National Park, Scotland, UK. July.

Claudio Contreras / Bluehead Wrasse (Thalassoma bifasciatum) juvenile cleaning Smooth Trunkfish (Lactophrys triqueter), Banco Chinchorro Biosphere Reserve, Caribbean region, Mexico, May

Alex Mustard / School of Oriental sweetlips (Plectorhinchus vittatus) gather tightly together as they rest during the day, with a Clown triggerfish (Balistoides conspicillum) and Midnight snappers (Macolor macularis...

Tony Wu / Crab-eye goby (Signigobius biocellatus), mimics crab with eye-spot markings on dorsal fins and back and forth movement. Loloata Island, Papua New Guinea.

Alex Mustard / Saddleback anemonefish (Amphiprion polymnus) barks a warning as it guards a clutch of developing eggs (beneath it) laid on a small stone, below a fold in its home, a Haddon's sea anemone (Stichoda...

Alex Mustard / Giant hogfish (Bodianus macrognathos) male yawning at a cleaning station run by juvenile Spanish hogfish (Bodianus rufus). Jardines de la Reina, Gardens of the Queen National Park, Cuba. Caribbean Sea...

Brandon Cole / Crescent-tail bigeyes (Priacanthus hamrur), and Grey reef sharks (Carcharhinus amblyrhynchos). French Polynesia, Pacific Ocean.

Brandon Cole / Masked butterflyfish (Chaetodon semilarvatus) Egypt, Red Sea.

Brandon Cole / Oceanic whitetip shark (Carcharhinus longimanus) and Pilotfish (Naucrates ductor) swimming under a stormy surface. Egypt, Red Sea.

Brandon Cole / Yellowfin tuna (Thunnus albacores) Baja, Mexico, Pacific Ocean.

Brandon Cole / Steel pompano (Trachinotus stilbe) fish swimming under stormy seas at Roca Redonda offshore Baja, Mexico, Pacific Ocean.

Doug Perrine / Yellowfin tuna (Thunnus albacares) and Pantropical spotted dolphins (Stenella attenuata) feeding on bait fish, Pacific Ocean off southern Costa Rica.

Sergio Hanquet / Yellowfin tuna (Thunnus albacares) hunting mackerel (Scomber colias) Tenerife, Canary Islands.

Claudio Contreras / Foureye butterflyfish (Chaetodon capistratus) couple feeding on coral, Guanahacabibes Peninsula National Park, Pinar del Rio Province, western Cuba.

Claudio Contreras / Black grouper (Mycteroperca bonaci), and Caribbean Reef Shark (Carcharhinus perezi), Jardines de la Reina / Gardens of the Queen National Park, Caribbean Sea, Ciego de Avila, Cuba.

Claudio Contreras / Black grouper (Mycteroperca bonaci), and Caribbean Reef Shark (Carcharhinus perezi), Jardines de la Reina / Gardens of the Queen National Park, Caribbean Sea, Ciego de Avila, Cuba.

David Hall / Split level of a Sockeye salmon (Oncorhynchus nerka) in shallow water; Adams River, British Columbia, Canada. October.

David Hall / Split level of Sockeye salmon (Oncorhynchus nerka) during migration; Adams River, British Columbia, Canada. October.

David Hall / Sockeye salmon (Oncorhynchus nerka) migration, Adams River, British Columbia, Canada. October.

David Hall / Sockeye salmon (Oncorhynchus nerka) migration, Adams River, British Columbia, Canada. October.

Shane Gross / Panamic Cushion Sea Star (Pentaceraster cumingi) and a school of Yellow-tailed Grunt (Anisotremus interruptus), Galapagos Island, Ecuador. December.

Franco Banfi / Blue shark (Prionace glauca) and Pilot fish (Naucrates ductor), Pico Island, Azores, Portugal, Atlantic Ocean

Franco Banfi / Blue shark (Prionace glauca) with fishing hook caught in mouth and Pilot fish (Naucrates ductor), Pico Island, Azores, Portugal, Atlantic Ocean

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 / Dugong (Dugong dugon) male, swims over seagrass meadow (Halophila stipulacea) accompanied by a young Golden trevally (Gnathanodon speciosus). Marsa Nabaa, Marsa Alam, Egypt. Red Sea

Alex Mustard / Dugong (Dugong dugon) male feeding on a seagrass meadow (Halophila stipulacea), accompanied by a young Golden trevally (Gnathanodon speciosus). Marsa Nabaa, Marsa Alam, Egypt. Red Sea

Alex Mustard / Dugong (Dugong dugon) male feeding on a seagrass meadow (Halophila stipulacea), accompanied by a young Golden trevally (Gnathanodon speciosus). Marsa Nabaa, Marsa Alam, Egypt. Red Sea

Shane Gross / Pink anemonefish (Amphiprion perideraion) living in symbiotic association with Magnificent sea anemone (Heteractis magnifica) Palau.

Shane Gross / Pink anemonefish (Amphiprion perideraion) living in symbiotic association with Magnificent sea anemone (Heteractis magnifica), Palau

Shane Gross / Dolphin fish / Mahi mahi (Coryphaena hippurus) off Cat Island, Bahamas.Non-ex