Can You Identify This Hybrid?

[Sicklid]

Can you ID this Hybrid? . The mantle is conspicuously like a T. squamosa... but the shell does not have the characteristic worn scutes of a T. squamosa, and instead looks worn and ribbed like a T. derasa. Someone had written in to Bob Fenner asking, and I was wondering also.

 

[K. Lee]

The shell looks like a T. gigas to me.

I think just like with corals color is a secondary characteristtic and a pretty weak tool for species identifivation in clams.

I thought "Teardrops" were only T. maxima, but, I was wrong.

 

[Peabody]

Hmmm....it's not a Gigas "proper" because they don't extend their mantles beyond the shell.

I wouldn't have guess it is a hybrid. I would have thought a rather unique maxima or squamosa. Are you sure it's a hybrid?

 

[K. Lee]

Hmmm....it's not a Gigas "proper" because they don't extend their mantles beyond the shell.

I wouldn't have guess it is a hybrid. I would have thought a rather unique maxima or squamosa. Are you sure it's a hybrid?

T. gigas sure do. Hippopus sp. don't.

But on closer looking, it appears there are tentacles on the outer incurrent siphon which are absent on T. gigas. That could be a function of the coloration on the mantle however. A close look at or into the incurrent siphon would help, a lot.

 

[Peabody]

Really? On the gigas I've seen (which admittidly isn't many!) the mantle barely extended beyong the shell. Is this not usually the case?

 

[Sicklid]

I called it a hybrid because Anthony at Wet Web Media called it a hybrid. Here is the original Q&A:



"Can you please identify this type of clam for me. It has a brownish look to it although it looks a little different in the picture. Thank You."

"I would need a better picture to be sure but you may have a very interesting clam here! Tridacnids are rather easy to identify but yours looks like it could be a hybrid of two species known to hybridize. The mantle is conspicuously like a T. squamosa... but the shell does not have the characteristic worn scutes of a T. squamosa, and instead looks worn and ribbed like a T. derasa. Still the picture is not clear enough. A close up of the shell and mantle separately would help if clear. Best regards, Anthony"

 

[AQUAN8TOR]

That clam looks like a very interesting and unique squamosa to me. Except for the color, and scutes, the pattern is identical to my squamosa. The shell doesn't seem to be creased enough for a maxima. Maybe its a derasa; if it is, it's especially colorful and patterned. Most derasas I've seen aren't nearly as 'marbled'---unlike a teardrop clam, which looks nothing like this clam. Also, I've never seen gigas clams with their mantles much beyond the shell, either; even in Knop's book, there are very few pictures of gigas clams with their mantles past the edge of the shells.

 

[K. Lee]

The clams pictured may have been startled. It is their nature to withdraw. Either shadows, or a camera flash would trigger a healthy giant clam to withdraw, or could.

Here's a pic I just took of my T. gigas.

 

[AQUAN8TOR]

nice clam. I definitely know about clam mantle contractions in all species, in response to shadow, movement, etc. I just had never seen one as open as yours apparently is, even in the MANY years I've been a hobbyist. I stand corrected. Thankyou.

 

[Gary Majchrzak]

jazzyreef- check out the "HYPER" mantle extension on my Tridacna {seen through this link on the front page of my website.}
http://home.rochester.rr.com/garysreef/
The mantle is so floppy some folks thought my clam was "gaping"!

sicklid- I think you have a T. squamosa with worn down scutes....
look at the frilly incurrent siphon. I believe T. derasa and T. squamosa have been known to interbreed...it's possible yours' might be a cross of the two.