Ryan Photographic - Cardiidae - Clams and cockles

Family Cardiidae

The family Cardiidae contains around 260 species in 39 genera. Exclusively marine, they are often eaten. They are typically referred to as the clams or cockles, but this term is also used for many other bivalve species. The family includes the largest of the bivalves, Tridacna gigas. A huge example of this is in several of the photos below. According to Wikipedia the largest T. gigas ever recorded measured 137 cm (4' 6"). The specimen below, based on my arm span measured around 150 cm (5') which would make it the largest giant clam on the planet. Divers in this area are very familiar with this animal. Someone please take a tape measure down with you and verify the size.

Giant clams in general are threatened by Southeast Asian clam boats. Workers go onto reefs at low tide and cut out the clam adductor muscles, leaving the dead clam on the reef. As all the giant clams are relatively slow-growing and the big ones produce the most eggs and sperm, this is pushing these amazing creatures towards extinction in several areas. Giant clams are farmed in some places.

The Tridacna clams obtain much of their food from symbiotic algae and, as a result, are restricted to shallow, clear, water. The clam makes small "glass" lenses which transmits the light into the mantle tissues.

Tridacna crocea Burrowing clam

Tridacna crocea Burrowing clam, Kri Eco, Raja Ampat, West Papua IMG_4248

Tridacna derasa Smooth giant clam

Tridacna derasa Giant clam blue siphon

Tridacna derasa Smooth giant clam siphon

Tridacna gigas, Giant clam

Tridacna gigas, Giant clam, Raja Ampat, West Papua IMG_9417

Tridacna gigas, Giant clam, Raja Ampat, West Papua IMG_9408

Tridacna gigas, IMG_3530, Giant giant clam, Matamanoa, Fiji

Tridacna gigas, Giant giant clam, Matamanoa, Fiji. There is some doubt as to whether T. gigas was ever in Fiji but it has been introduced. IMG_3530

Tridacna maxima Small giant clam

Tridacna maxima Maxima giant clam, Ledge-end, GBR IMG_8223

Tridacna maxima, Raja Ampat, West Papua IMG_1184

Tridacna maxima, Fiji.

Tridacna squamosa Fluted giant clam

Tridacna squamosa, Fluted giant clam, Kadavu, Fiji, 2007

Ryan Photographic - Cardiidae - Clams and cockles

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Family Cardiidae

The Tridacna clams obtain much of their food from symbiotic algae and, as a result, are restricted to shallow, clear, water. The clam makes small "glass" lenses which transmits the light into the mantle tissues.

Tridacna crocea Burrowing clam

Tridacna crocea Burrowing clam, Kri Eco, Raja Ampat, West Papua IMG_4248

Tridacna derasa Smooth giant clam

Tridacna derasa Smooth giant clam siphon

Tridacna gigas, Giant clam

Tridacna gigas, Giant clam, Raja Ampat, West Papua IMG_9417

Tridacna gigas, Giant clam, Raja Ampat, West Papua IMG_9408

Tridacna gigas, Giant clam, Raja Ampat, West Papua IMG_9408

Tridacna gigas, Giant giant clam, Matamanoa, Fiji. There is some doubt as to whether T. gigas was ever in Fiji but it has been introduced. IMG_3530

Tridacna maxima Small giant clam

Tridacna maxima Maxima giant clam, Ledge-end, GBR IMG_8223

Tridacna maxima, Raja Ampat, West Papua IMG_1184

Tridacna maxima, Fiji.

Tridacna squamosa Fluted giant clam

Tridacna squamosa, Fluted giant clam, Kadavu, Fiji.

Tridacna squamosa mantle detail, Fiji.

Tridacna squamosa inhalant siphon vertical

Tridacna squamosa fluted giant clam, Taveuni, Fiji-4749

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