Norbert Wu / Flying Fish (Exocoetidae) uses large pectoral fins to glide through the air, Saba Island, Dutch Antilles

Gabriel Rojo / Southern right whale pectoral fin {Balaena glacialis australis} Patagonia, Argentina

Hiroya Minakuchi / Southern Right Whale (Eubalaena australis) pectoral fin, Valdes Peninsula, Argentina

Mark Carwardine / Humpback whale, pectoral fin slapping water {Megaptera novaengliae} Ecuador, Machalilla

Mark Carwardine / Watching Humpback whale from boat, New England, USA {Megaptera novaengliae}

Mark Carwardine / Humpback whale, pectoral fin slapping water {Megaptera novaengliae} USA Atlantic coast

Alex Mustard / 2020VISION / Pair of Reticulated dragonets (Callionymus reticulatus) spawning. The larger male is carrying the female up into the water column, balanced on his pectoral fin, the males breed only once in their life...

Alex Mustard / 2020VISION / Pair of Reticulated dragonets (Callionymus reticulatus) spawning - the larger male is carrying the female up into the water column, balanced on his pectoral fin, the males breed only once in their lif...

Alex Mustard / Peacock flounders (Bothus lunatus) pair in mating ritual at sunset, female on left is swollen with eggs while the male has errected his large pectoral fin as a display, Georgetown, Grand Cayman, Cayma...

Jeff Rotman / Pectoral fin of Male Steephead Parrotfish (Chlorurus / Scarus microrhinos). Great Barrier Reef, Coral Sea, Australia.

Doug Perrine / Reef manta ray (Manta alfredi formerly Manta birostris) with shark bite out of pectoral fin, among group feeding on plankton, Hanifaru Bay, Baa Atoll, Maldives, Indian Ocean, October

Juergen Freund / WWF Philippines Donsol Research Coordinator taking a photo of the left pectoral fin of a passing Whale shark (Rhincodon typus) for photo identification, to be submitted to www.whaleshark.org. Donsol,...

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) pectoral fin slapping, watched by Graeme Ellis and family, off of Hawaii

Alex Mustard / A lemon shark (Negaprion brevirostris) drags its pectoral fin through the sand as it swims accompanied by Remoras / Sharksuckers (Echeneis naucrates). Little Bahama Bank. Bahamas. Tropical West Atlant...

Alex Mustard / Remora / Sharksucker (Echeneis naucrates) hitches a ride beneath the pectoral fin of a Lemon shark (Negaprion brevirostris). Little Bahama Bank. Bahamas. Tropical West Atlantic Ocean.

Hiroya Minakuchi / Orca (Orcinus orca) pectoral slap, Prince William Sound, Alaska

Hiroya Minakuchi / Orca (Orcinus orca) pectoral slap, Prince William Sound, Alaska

Mark Carwardine / Humpback whale (Megaptera novaeangliae) raising flipper / pectoral fin into the air, Sea of Cortez, Baja California, Mexico

Tim Laman / Spotfin lionfish (Pterois antennata) detail of pectoral fin. Bali, Indonesia.

Jeff Rotman / Close up of Pectoral fin of Sohal surgeonfish (Acanthurus sohal) Red Sea, Egypt

Jeff Rotman / Pectoral fin of a Rusty parrotfish (Scarus ferrugineus) Red Sea, Egypt

Jeff Rotman / Close up of Pectoral fin of Sohal surgeonfish (Acanthurus sohal) Red Sea, Egypt

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) female courted by cooperating causesd bubbles by slapping surface with pectoral fin, Maui, Hawaii - notice must accompany publication; photo obtained under NMFS...

Steven David Miller / Humpback Whale (Megaptera novaeangliae) slapping its pectoral fin. Hervey Bay, Queensland, Australia

Steven David Miller / Humpback Whale (Megaptera novaeangliae) slapping its pectoral fin. Hervey Bay, Queensland, Australia

Jeff Rotman / Wild Bottlenose Dolphin (Tursiops truncatus) with Reef Octopus {Cyanea sp} attached to pectoral fin, Nuweiba, Egypt - Red Sea.

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) waving pectoral fin, Maui, Hawaii - notice must accompany publication; photo obtained under NMFS permit 0753-1599

Jeff Rotman / Pectoral fin of White tip reef shark (Triaenodon obesus) Red Sea, Egypt

Fred Bavendam / Spotted Handfish (Brachionichthys hirsutus) showing modified pectoral fins used for walking, Tasmania, Australia

Fred Bavendam / Handfish (Brachionichthys sp) guarding clutch of eggs showing modified pectoral fins used for walking, Tasman Peninsula, Australia

Fred Bavendam / Handfish (Brachionichthys sp) showing modified pectoral fins used for walking, Tasman Peninsula, Australia

Fred Bavendam / Red Handfish (Brachionichthys politus) showing modified pectoral fins used for walking, Tasman Peninsula, Australia

Fred Bavendam / Common Searobin (Prionotus carolinus) pair showing hand-line pectoral fins, Rockport, Maine

Fred Bavendam / Oriental Flying Gurnard (Dactyloptena orientalis) swimming over ocean bottom with fins outstretched to confuse predators, Milne Bay, Papua New Guinea

Chris Newbert / Scorpionfish (Scorpaenopsis sp) pectoral fin detail, Indonesia

Suzi Eszterhas / Humpback Whale (Megaptera novaeangliae) pectoral fin slapping, Sea of Cortez, Baja California, Mexico

Suzi Eszterhas / Gray Whale (Eschrichtius robustus) pectoral fin, San Ignacio Lagoon, Baja California, Mexico

Suzi Eszterhas / Gray Whale (Eschrichtius robustus) pectoral fin, San Ignacio Lagoon, Baja California, Mexico

Juergen Freund / Pectoral fin of Humpback whale (Megaptera novaeangliae) slapping, off coast of Tonga

Matthew Maran / Pectoral fin of juvenile Humpback Whale {Megaptera novaeangliae} Barkley Sound, Vancouver Island, BC, Canada

Nick Garbutt / Humpback Whale (Megaptera novaeangliae) waving pectoral fin / flipper in waters off Princes Royal Island, Great Bear Rainforest, British Columbia, Canada.

Florian Graner / Haddock (Melanogrammus aeglefinus) showing characteristic thumbprint marking above pectoral fin, Norway

Constantinos Petrinos / Giant frogfish {Antennarius commerson} Sulawesi Note - Pectoral fin adapted for 'walking'.

Jeff Rotman / Whitetip Reef Shark (Triaenodon obesus) close-up of pectoral fin with whhite tip. Egypt, Red Sea.

Hiroya Minakuchi / Blue Whale (Balaenoptera musculus) showing pectoral fin, endangered, Sea of Cortez, Mexico

Constantinos Petrinos / Giant Frogfish pectoral fin and gill opening (Antennarius commerson) Sulawesi, Indonesia

Sue Flood / Pectoral fin of Humpback whale (Megaptera novaeangliae), Kingdom of Tonga, South Pacific. 2005

Sue Flood / Pectoral fin of Humpback whale raised above surface {Megaptera novaeangliae} Antarctic Penin.

Todd Pusser / Wounded pectoral fin of Grey whale calf after attack by killer whale. California, USA.

Todd Pusser / Humpback whale pectoral fin {Megaptera novaeangliae} Stellwageb Bank, MA, USA

Constantinos Petrinos / Giant frogfish - pectoral fin adapted for 'walking'. Sulawesi {Antennarius commerson}

Chris Newbert / Humpback Whale (Megaptera novaeangliae) swimming underwater with pectoral fin raised, Kona, Hawaii

Chris Newbert / Half-spotted Grouper (Cephalopholis hemistiktos) pectoral fin detail, Red Sea, Egypt

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

Chris Newbert / Candeloma Parrotfish (Hipposcarus harid) detail of pectoral fin of sleeping fish, Red Sea, Egypt

Fred Bavendam / Blue-barred Parrotfish (Scarus ghobban) pectoral fin of a male as it sleeps on the reef at night, Andaman Sea, Thailand

Fred Bavendam / Swarthy Parrotfish (Scarus niger) pectoral fin, Andaman Sea, Thailand

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) missing the left pectoral fin, underwater, Hawaii

Norbert Wu / Flying Gurnard (Dactylopterus volitans) unfolds large wings to confuse and threaten predators, Saba Island, Netherlands Antilles, Caribbean

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) pectoral slap

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) missing left pectoral, Hawaii

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) pectoral slaps, Maui, Hawaii - notice must accompany publication; photo obtained under NMFS permit 987

Juergen Freund / Pectoral fin of Humpback whale. Gorgona Island, Columbia

TOM WALMSLEY / Southern right whale pectoral fin, off coast of South Africa {Balaena glacialis australis}

Jeff Rotman / Spotted scorpionfish, pectoral fin {Scorpaena guttata} Pacific off California, USA

Jeff Rotman / Garibaldi fish, pectoral fin, {Hypsypops rubicunda} Pacific USA

Jeff Rotman / Garibaldi fish, close up of pectoral fin {Hypsypops rubicunda} California, Pacific Ocean, USA

Jeff Rotman / Queen angelfish close-up of gills and pectoral fin {Holacanthus ciliaris} Bahamas, Caribbean

Jeff Rotman / Queen angelfish close-up of pectoral fin {Holacanthus ciliaris} Bahamas, Caribbean

Jeff Rotman / Lunar tailed black cod (Variola louti) pectoral fin detail, Australia Great barrier reef

Jeff Rotman / Pecotral fin of Eyestripe surgeonfish (Acanthurus dussumieri) close-up detail, Great barrier reef

Hiroya Minakuchi / Southern Right Whale (Eubalaena australis) pectoral fin, Valdes Peninsula, Argentina

Richard Herrmann / Blue Whale (Balaenoptera musculus) pectoral fin during surface feeding, San Diego, California

Ian Coleman / Illustration of pectoral fin of Blue shark (Prionace glauca). Endangered / threatened species.

Ian Coleman / Illustration of pectoral fin of Silky shark (Carcharhinus falciformis). Endangered / threatened species.

Ian Coleman / Illustration of pectoral fin of Great hammerhead shark (Sphyrna mokarran). Endangered / threatened species.

Ian Coleman / Illustration of pectoral fin of Gray reef shark (Carcharhinus amblyrhynchos). Endangered / threatened species.

Ian Coleman / Illustration of pectoral fin of Caribbean reef shark, (Carcharhinus perezi). Endangered / threatened species.

Ian Coleman / Illustration of pectoral fin of Galapagos shark (Carcharhinus galapagensis). Endangered / threatened species.

Ian Coleman / Illustration of pectoral fin of Great white shark (Carcharodon carcharias). Endangered / threatened species.

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) singing, missing one pectoral fin, Hawaii

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) pectoral slap, Southeast Alaska

Gabriel Rojo / Southern right whale pectoral fin {Balaena glacialis australis} Patagonia Argentina