A few days ago the Washington Post announced that the National Zoo in Washington, D.C. is now home to 10 giant clams of the species Tridacna crocea. You may think the National Zoo is a peculiar place for clams especially since the National Aquarium now has a branch in D.C., however the clams are suitably placed in the invertebrate exhibit and I highly recommend you spend time there if you ever make it to the National Zoo. It is one of the quieter exhibits, housed in air conditioning (what’s not to love about that?), and has an exhibit for chambered nautilus, a BCS species favorite.
With all that being said, it seems as though if you want to learn about T. crocea, smallest of all the giant clams species, you’ll have to come to D.C. (or simply read the article in the Post linked above)!
So, I am going to take this opportunity to brief you on a real giant clam. This posts features the largest and most elaborately colored of all the giant clam species, Tridacna gigas (pictured right). This being the largest of all living bivalves, T. gigas holds it own at a whooping 500 lbs, 3 ft 10 in length and 30 in wide. The average male American black bear is about that size. At 500 lbs, it’s no wonder they cannot shut their two shells together (It’s like when I to pack for a weekend vacation).
These hermaphrodites, found in the Indo-Pacific, are planktonic when young and sessile as adults. The diet of these placid creatures is algae as they are filter feeders.
There is concern among conservationists that T. gigas is being exploited as they are harvested for food (a delicacy in Japan) and is a popular acquisition in the aquarium trade.
Image (c) manandmollusc.net.