What Species Is This Clam? (Photo)

[Reinhold]

I was told that this clam is a T.derasa. However, I thought derasa clams had a smoother shell. Is this a derasa, crocea or maxima?

[golfish]

I have never seen a Derasa that color.......It looks like a Crocea to me

[reefhead]

Its a Crocea!


And a very pretty one 2!!!

Enjoy,
Joe

[scubadude]

I would say that its a crocea too probably. But I have seen pics from your tank Reinhold and they have a nice pinkish tint and Im wandering what this clam looks like under say 6500k pure bulbs I am assuming that you have a good supplemnt of Actinic to see the clam with a pure white light and from above would tell exactly what it is IMO.

Shes a beauty whatever species she is though

[Reinhold]

Here is a shot without the actinics, (03 actinic, 2 X 55W PC's from lampsnow.com.)

I could not get the stupid Killer Hawkfish to move, as almost everytime he sees the camera, he comes and sits down in front of it.

[scubadude]

Now I hink it looks like a Maxima Im not sure though Love the hawkfish 2

[reefhead]

its all in the ridges, not the color

[Ninong]

I am inclined to believe that it could be a T. derasa. You could erase all doubt very quickly by looking at the byssal orifice. Derasa would have a narrow byssal orifice, whereas crocea would have a wide byssal orifice. In fact, crocea has the largest byssal orifice relative to the size of the shell. A derasa shell usually has six vertical folds and is symmetrical. A crocea shell usually does not exhibit vertical folds and instead the lower half is relatively smooth and free of folds. A maxima would have an asymmetrical elongated shell.

Ninong

[golfish]

Now it looks a little more natural. It still looks like a Crocea

[Reinhold]

Thanks everyone.

I count 6 vertical grooves, and the shell halves are very symmetrical, allowing the clam to close completely.

The byssal orifice on this 2 1/2 inch clam measured about 1/4 inch across. It is now stuck down to the rock by the gland or whatever it is at the orifice.

Based on what Ninong said, it probably is a derasa. Good for me, since I have PC lights and not metal halides.

[smokinreefer]

Nope, it's most likely a crocea. deresa's have a distinct look to them. just do a search and look at a few pics, you'll see what i mean. and the maxima's have more pronounced scutes.

well i'll tell you this forsure, if you paid derasa prices for it, you got a deal!!

i'm not gonna bash you and say you need halides for it, just keep it in the upper half of the tank.

BTW, it is a very nice clam! enjoy.

[petpoor]

Looks like a Crocea to me also, most Deresa's I have seen including mine have smooth shells with no scutes showing.
Tom

[Reinhold]

[golfish]

Yeah, I kept a Crocea under 4x55 watt PC's in my old 55 for a long time. It was way up high. I some how introduced something to my old tank that killed all my clams......here's a picture of it.

Like Tom said "most Deresa's I have seen including mine have smooth shells with no scutes showing"

[golfish]

Here's an old pic of my Derasa.....

[Reinhold]

Golfish:

The clam I have sure looks alot like your crocea. The shell doesn't look anything like the derasa pic you posted.

I will eventually add a metal halide hood to my tank, but in the meantime, it's about halfway up in my 60 stuck on a rock shelf. I hope it's okay there. The actinics are 2 X 55W and the whites are 2 X 65W 8800 K.

[Ninong]

If your clam is a T. crocea, this is what the byssal orifice would look like:



T. crocea has the largest byssal orifice relative to the size of the shell of all the Tridacnids. T. derasa has a narrow gap for a byssal orifice.

Ninong

[Reinhold]

Ninong

The byssal orifice was only about 1/4 inch across and was actually a little off center instead of centered, like the photo. It is pretty well stuck down on the rock now, so I can't take a photo of it.

It seems happy where it is, but I sure am confused.

[Ninong]

The shell of your clam seems to me to be similar to these derasa shells.



Ninong

[piege]

It's a crocea. I don't think there's really that much doubt.
You say the bysall opening is only 1/4 inch, but you are measuring it while occupied. That pic that was shown was of a dead clam with no tissue to help cover up the actual opening.

Your clam isn a crocea.

JP