Juergen Freund / Syphon of Giant clam {Tridacna gigas} on seabed, Indo-pacific

Juergen Freund / Giant clam {Tridacna gigas} on seabed, Indo-pacific

Juergen Freund / Giant clam {Tridacna gigas} on seabed, Indo-pacific

Juergen Freund / Clam {Tridacna sp} encrusted with corals, Indo-pacific

Juergen Freund / Detail of syphon of Giant clam {Tridacna gigas} Indo-pacific

GEORGETTE DOUWMA / Small giant clam (Tridacna maxima) in Porites coral. Andaman Sea, Thailand

Georgette Douwma / Crocus giant clam (Tridacna crocea) Rinca, Indonesia

GEORGETTE DOUWMA / Mantle of Small giant clam (Tridacna maxima) Andaman Sea, Thailand

Georgette Douwma / Mantle of Crocus giant clam (Tridacna crocea) Rinca, Indonesia

Suzi Eszterhas / Grizzly Bear (Ursus arctos horribilis) mother and one and a half year old cub digging for clams, Katmai National Park, Alaska

Suzi Eszterhas / Grizzly Bear (Ursus arctos horribilis) cub playing with clam, Katmai National Park, Alaska

Steven David Miller / Looking down into the mantle of a Giant clam {Tridacna sp} Great Barrier Reef, Australia

GEORGETTE DOUWMA / Fluted giant clam (Tridacna squamosa) and Fire coral (Millepora sp.), Red Sea, Egypt.

Nature Production / Clam {Pisidium nipponense} with siphon extended, Wakayama, Japan

Nature Production / Pea crab {Pinnotheres sinensis} parasite of Clam {Ruditapes philippinarum} Japan

Tim Edwards / Giant Clam on coral reef (Tridacna sp) Great Barrier Reef, Australia

GEORGETTE DOUWMA / Giant clam feeding {Tridacna gigas} Australia

GEORGETTE DOUWMA / Close up of exhalent syphon of Giant clam {Tridacna gigas} Great Barrier Reef, Queensland, Australia

GEORGETTE DOUWMA / Giant clam {Tridacna gigas} Great Barrier Reef, Australia

GEORGETTE DOUWMA / Close up of inhalent syphon of Giant clam {Tridacna gigas} Great Barrier Reef, Queensland, Australia

GEORGETTE DOUWMA / Giant clam {Tridacna sp} Great Barrier Reef, Australia

GEORGETTE DOUWMA / Giant clam {Tridacna gigas} Great Barrier Reef, Australia

GEORGETTE DOUWMA / Giant clam {Tridacna sp} Great Barrier Reef, Australia

Juergen Freund / Siphon of Giant clam (Tridacna sp) Philippines

Juergen Freund / Detail of Siphon of Giant clam (Tridacna sp) Red Sea

Steven David Miller / Coquina clams (Donax variabilis) small bivalves living just under surface of sand at water line, Florida, USA

Juergen Freund / Juvenile Giant clam (Tridacna sp) held in hand on commerical clam farm, Palau, Micronesia

Juergen Freund / Giant clam (Tridacna sp) in breeding pool on commerical clam farm, Palau, Micronesia

Juergen Freund / Juvenile Giant clams (Tridacna sp) in bucket on commerical clam farm, Palau, Micronesia

Juergen Freund / Juvenile Giant clams (Tridacna sp) in breeding pens on commerical clam farm, Palau, Micronesia

Chris Newbert / Giant Clam (Tridacna gigas) mantle detail, world's largest and heaviest mollusk, 20 feet deep off of Solomon Islands

Chris Newbert / Giant Clam (Tridacna gigas) world's largest and heaviest mollusk, 10 feet deep off of Solomon Islands

Chris Newbert / Giant Clam (Tridacna gigas) mantle detail, 40 feet deep, Papua New Guinea

Willem Kolvoort / Underwater view of Greater european pea clam(Pisidium amnicum) in garden pond, Holland

Simon Colmer / European fingernail clam / Freshwater cockle {Sphaerium corneum} showing siphons, Sussex, UK

Doug Perrine / Diver with Giant clam {Tridacna gigas} Great Barrier Reef, Queensland, Australia

Doug Perrine / Diver with Giant clam {Tridacna gigas} Great Barrier Reef, Queensland, Australia

Doug Perrine / Mantle of Coral clam / scallop {Pedum spondyloideum} visible in coral, Flinders sea, Coral sea, Australia

Willem Kolvoort / Greater european pea clams / Pea mussels (Pisidium amnicum) filter feeding in garden pond, Holland

Willem Kolvoort / Greater european pea clams / Pea mussels (Pisidium amnicum) filter feeding in garden pond, Holland

GEORGETTE DOUWMA / Giant clam {Tridacna maxima} Lembeh Strait, North Sulawesi, Indonesia.

GEORGETTE DOUWMA / Giant clam {Tridacna gigas} Bunaken NP, North Sulawesi, Indonesia

GEORGETTE DOUWMA / Giant clam (Tridacna gigas) largest species of bivalve in the world. Great Barrier Reef, Australia.

Juergen Freund / Mangrove forest and shallow coral reef with Giant clam, split level, Papua New Guinea

Juergen Freund / Shallow coral reef with Giant clam {Tridacna sp} and snorkeler, Papua New Guinea

Juergen Freund / Mangrove forest and shallow reef with clam, split level, Papua New Guinea

Doug Perrine / Rough file clam / Flame scallop {Lima scabra} Caribbean

Doug Perrine / Giant clam, close up of mantle {Tridacna sp} Micronesia

Juergen Freund / Giant clam exposed at low tide {Tridacna gigas} Great Barrier Reef, Australia.

Juergen Freund / Coral reef exposed at low tide & giant clam, Low Isles, Great Barrier Reef, Australia

Tom Vezo / Surf Scoter (Melanitta perspicillata) male in water feeding on clam, California

Birgitte Wilms / Giant Clam (Tridacna sp) mantle detail, 20 feet deep, Solomon Islands

Norbert Wu / Giant Clam (Tridacna sp) has symbiotic algae within mantle for photosynthesis, Sangalakki Island, Borneo

Chris Newbert / Small Giant Clam (Tridacna maxima) siphon detail, showing colorful symbiotic photosynthetic algae growing in Giant Clam's flesh, algae produces oxygen while consuming waste ammonia, Solomon Islands

Chris Newbert / Octopus (Octopus sp) eating Giant Clam (Tridacna sp), Solomon Islands

Chris Newbert / Small Giant Clam (Tridacna maxima) detail of mantle, Coral Sea

Chris Newbert / Giant Clam (Tridacna gigas) detail of mantle, Palau

Jan Vermeer / Selection of bivalve shells

Fred Bavendam / Small Giant Clam (Tridacna maxima) sitting in front of a small colony of Soft Coral (Dendronephthya sp), Great Barrier Reef, Queensland, Australia

Fred Bavendam / Giant Clam (Tridacna gigas) on ocean floor, Milne Bay, Papua New Guinea

Norbert Wu / Giant Clam (Tridacna sp) that has algae within mantle for photosynthesis and diver, Sangalakki Island, Borneo

Fred Bavendam / Small Giant Clam (Tridacna maxima) mantle, Lembeh Strait, Indonesia

Fred Bavendam / Small Giant Clam (Tridacna maxima) mantle, Lembeh Strait, Indonesia

Fred Bavendam / Fire Clam (Ctenoides ales) produces a bioluminescence that streaks along the edge of its mantle, Manado, North Sulawesi, Indonesia

GEORGETTE DOUWMA / Crocus giant clam {Tridacna crocea} Banda Is, Moluccas, Indonesia

Juergen Freund / Diver and Giant clam {Tridacna gigas} Great Barrier Reef, Australia

Juergen Freund / Diver + Giant clam in coral reef {Tridacna gigas} Great Barrier Reef, Australia

Juergen Freund / Close up of Giant clam mantle {Tridacna deresa} Great Barrier Reef, Australia

Michael Pitts / Giant clam {Tridacna gigas} exposed at low tide, Montgomery reef, Kimberley, W Australia

GEORGETTE DOUWMA / Giant clam mantle {Tridacna gigas} Great Barrier Reef, Queensland, Australia

Doug Perrine / Commensal goby {Luposicya lupus} on mantle of Giant clam, Sipadan Island, Borneo, Malaysia (Non-ex).

Juergen Freund / Exhale opening of Tridacna clam (Giant clam) Indo-pacific,

Steven David Miller / Tridachna giant clam, on coral reef in shallow lagoon, Great Barrier Reef, Australia

Juergen Freund / Giant clam {Tridacna sp} with tube corals. Philippines.

Juergen Freund / Close up of siphon of giant clam {Tridacna sp} Red Sea, Egypt

Juergen Freund / Close up of siphon of Giant clam {Tridacna sp} Red Sea, Egypt

GEORGETTE DOUWMA / Crocus giant clam {Tridacna crocea} Red Sea, Egypt

Juergen Freund / Giant clam and diver {Tridacna gigas} Indo-Pacific

Juergen Freund / Starfish feeding on clam at low tide, Vancouver Island, Canada

David Hall / Pile of discarded Giant Clam shells {Tridacna gigas} delicacy, Papua New Guinea

GEORGETTE DOUWMA / Giant clam close up of exhalent siphon {Tridacna gigas} Great Barrier Reef, Australia

GEORGETTE DOUWMA / Giant clam showing siphon {Tridacna gigas} Great Barrier Reef, Australia

GEORGETTE DOUWMA / Giant clam close-up of inhalent siphon {Tridacna gigas} Great Barrier Reef, Australia

David Hall / Close up of Giant clam mantle (Tridacna sp) Fiji

David Hall / Giant clam siphon - Colours come from symbiotic algae in tissues. Red Sea

Juergen Freund / Exhalation hole of Giant clam {Tridacna sp} Indo Pacific

Juergen Freund / Exhalation hole of Giant clam {Tridacna sp} Indo Pacific

Juergen Freund / Exhalation hole of Giant clam {Tridacna sp} Indo-Pacific

Juergen Freund / Coral Clam in the Pacific off Phillippines

Juergen Freund / Giant clam on sea bed, Indo-Pacific

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) mother and cub digging for clams on tidal flats, Lake Clark National Park, Alaska

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) mother and cub digging for clams on tidal flats, Lake Clark National Park, Alaska

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) mother and cub digging for clams on tidal flats, Lake Clark National Park, Alaska

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) mother and cub digging for clams on tidal flats, Lake Clark National Park, Alaska

Roberto Rinaldi / Close-up up of lips of giant clam (Tridacna gigas), Palau, Micronesia.

Roberto Rinaldi / Diver watching a Giant clam (Tridacna gigas), Flinders Reef, Australia