clam question

[Zos4me]

i picked up this clam and im not sure what kind it is. It kind of looks like a squimosa but it has an outline of blue around the mantle.Pic isnt that great but hopefully can be identified
Also im being stupid here but what does the clam need light for. Living on the ocean all my life I have never heard this
Thanks in advance

 

[DSC reef]

Tridacna derasa, very nice clam.

 

[Richard the Reefer]

Love my derasa!

 

[Zos4me]

Thanks one of my favorite critters

 

[Zos4me]

Love my derasa!

i love how blue yours is

 

[DSC reef]

The blue one would be a maxima, the clam on the right is the derasa, I love the thin lines.

 

[Zos4me]

So im guessing my derasa will develop more of the blue lines as it grows .I like that

 

[DSC reef]

Not exactly, there are different patterns and colors between the mantles and yours seem to be broken up a bit more. In this pic you can see the distinct pattern differences between 2 of our derasa clams we had. The 2 left are the derasa.

 

[rkpetersen]

Yes, Tridacna derasa. Easiest way to tell them from other species is the very smooth shell that derasas have; no scutes sticking out. Also the mantle tissue is usually brownish/golden in color with a blue rim, as with yours.

All tridacnas need good light although the derasa needs the least of the various species. Tridacna clams need light because, like corals, they have millions of zooxanthellae algae embedded in their tissue. The algae produce excess sugars and other nutrients which the tridacnas then live on. Tridacnas are filter feeders too but studies have shown that they can almost get by on just what the algae provide, if there's enough light.

 

[Richard the Reefer]

Got mine for 60 bucks! Couldn't be happier. But I wish I could move my maxima, it's foot is down on a rock that won't allow him to open all the way

 

[Zos4me]

Thanks for the info.I learn so much everytime i post