Tridacna derasa
Picture taken July 1999, Sony Mavica FD91 digital camera, no flash.

This was purchased on June 27th, 1999.

This clam is about 5 inches long front to back and about 3 inches tall.

T. derasa can reach up to 20 inches in size. They tend not to be as pretty as T. maximas or T. croceas but they can still have very bright patterns. Typically Derasa have a very smooth shell. In nature they can often be found on the outer edge of the reef.

Tridacna derasa 2 months later
Picture taken September 1999, Sony Mavica FD91 digital camera, no flash.

This is the same clam picture to the left showing 2 months of growth. That is a growth ring close to 1/2 inch thick. This clam was also moved to the center of the tank where the light is stronger.

Clam growth this rapid takes a strong toll on calcium level in the tank and keeping up with calcium demand is getting harder.

Tridacna derasa 11 months later
Picture taken August 2000, Nikon Coolpix 950 digital camera, no flash.

The clam has not gained much height since the last picture but is has increased its mass significantly. You can see how the growth of the shell has changed and the last growth spurt has been completely covered in coralline algae.

Tridacna derasa - mantel close-up. Picture taken October 2000.
Nikon Coolpix 950 digital camera with Tiffen 10x and 7x Close-up lens, no flash.

This is an extreme close-up of the mantle. You can just about see individual cells that make up the colorful mantels. The black dots surrounded with blue are eye spots which are used to detect shadows passing over the clam.

Tridacna derasa - 14 months later.
Picture taken October 2001, Nikon Coolpix 950 digital camera,no flash.

On October 21st, 2001 I removed the clam from the tank to measure it. It was just over 8 inches long and 4 inches wide when closed! It stands just under 5 inches tall and 6 inches wide when fully expanded.

The clam insists on being oriented this way which makes it difficult to get a good picture of. The actinincs are off. One thing worth noting is that this clam has switched from being mainly blue in color to mainly yellow in color when viewed from above.

Tridacna derasa - 4 months later.
Picture taken February 2002, Nikon Coolpix 950 digital camera,no flash.

I'm just amazed how golden this clam has gotten. Being close to this montipora even makes it seem more yellow. Adds some nice color to the tank. (The montipora that was overgrowing it was traded back to the LFS shortly after this picture was taken).

Tridacna derasa - Top View.
Picture taken March 2002, Nikon Coolpix 950 digital camera,no flash.

As most of you knwo the color of the clam changes when viewed from the top. Just to show that the yellow isn't something from a crazy light angle here is a picture from the top. As you can see no hints of any blue at all. The rim does show some signs of green however.