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FAQs about Giant Clams, family Tridacnidae 3

Related Articles: Got Tridacna? A beginner's guide to keeping Tridacnid clams by Laurie Smith, Example Chapter from NMA Reef Invertebrates book, on Giant Clams, Tridacnids, A Brief Guide to the Selection and Placement of Tridacnid Clams by Barry Neigut, Tridacnid Health: Pinched Mantle Syndrome in Giant Clams by Dr. David Basti, Deborah Bouchard & Barry Neigut, Bivalves, Mollusks, Lighting Marine Invertebrates

Related FAQs: Tridacnids 1, Tridacnids 2, Tridacnids 4, Tridacnid Clam BusinessTridacnid Identification, Tridacnid Behavior, Tridacnid Selection, Tridacnid Compatibility, Tridacnid Systems, Tridacnid Lighting, Tridacnid Placement, Tridacnid Feeding, Tridacnid Disease, Tridacnid Reproduction, Bivalves, Bivalves 2, Lighting Marine Invertebrates,

Predatory Polyclad...

Zo's "kitty in clam" photo... :-) I was looking through the sample chapter, and my husband spotted a kitty resting in a clam in one of Zo's photos. I thought I'd pass along an annotated/explanation version...hope ya don't mind. --Ananda
<Neat! Bob F.>

Shrimp in Clam gills WWM crew, I hope your New Years is going well!  Please do be careful if you are on the roads this New Years Eve!   <thanks kindly... Happy New Years!> I have a quick couple of questions! I have a 5" fat, round T. squamosa. First question - I looked inside his exhalant siphon and lo and behold, there is a shrimp living in there!  It is small, clear with lots of black spots all over it.  I don't know what to think, or do for that matter.   <I have been e-mailing Daniel Knop (author of Giant Clams) about this recently as it has come up several times. The shrimp does appear to be at least mildly parasitic- feeding on gill tissue in part. Large clams seem to live with this fascinating arthropod with seemingly little or no ill effects. Your call on removal. May I ask you to take some hi-res photos is you have a good digital camera? You can e-mail them here or to me personally at readingtrees@yahoo.com> Second question - the inhalant siphon is large, and I'm wondering if it is gaping.  I researched clams before purchasing and know that it is very hard to diagnose gaping, as all clams are different.   <hmmm... still... gaping clams are unmistakable. They are slow to respond and just don't look well. I say if it was gaping, you'd know it!> The siphon is about 2" long and is normally open to about 1/2" to 5/8" wide.  When it wants to the clam can almost completely close it.   <a good sign> Overall the color is great, the clam reacts very quickly and very strongly to literally all stimuli, even if I just turn to peer closer at him he'll often cringe up for a second.   <excellent> It is my first clam, so I'm a bit apprehensive.  Much like a new mother I am sure!   <is this the first time you've been called a mother? <G>> Thank you for your time yet again! RVM <Heehee... our great pleasure. Anthony>

Tridacnid shrimp in gills Hmm, what is slide film?   <film that is developed to produce slides for a slide projector rather than paper prints> I'm no professional photographer by any means, <no worries... neither am I <G>> and unfortunately I am very ignorant of much terminology/methodology involved with photography.  I've not the time for another hobby. <understood and agreed> There are a few pics of the shrimp on reefs.org.  Someone else had a teardrop T. maxima die and found a pair of them in there.  Let me give you the thread.  I will still send you pics or if possible the slide film you are referring to. I feel sorry for the clam in the thread.  It was an absolutely gorgeous and >stunning specimen.   http://reefs.org/phpBB2/viewtopic.php?t=23428&highlight= <thanks for the tip, my friend. Best regards, Anthony>

Tridacnid Gill shrimp Anthony, I got the pictures taken.  Unfortunately I don't have a zoom attachment for my 35mm so I couldn't get close at all.  I'll have the pictures developed and scanned tomorrow so we'll see how they turn out.  My digital camera is dead.  I'm going to see if I can afford to purchase another one and get some close-ups. <great thanks for your efforts> For now I will describe these shrimp as well as I can.  I am not very familiar with their anatomy so I apologize for my rather elementary descriptions.  Also this will be in a "stream of consciousness" format, so it may not be quite so organized as it should. Oh, I should add that there are two shrimp in there.  I saw them both at the same time tonight.   <very cool> Both shrimp resemble flattened out cleaner type shrimp.  One is about 30mm long, the other 20mm.  They are clear with red dots.  I thought they were black at first but upon closer inspection they are red.  The dots cover the entire body, claws, legs, tail, everything except antennae, which are clear.  It is also very uniform coverage.  Each dot seems very evenly spaced relative to the dots around it.  There don't appear to be any other markings on them at all.  The smaller one has noticeably darker and more "substantial" internal organs than the other as well.  I believe it likely that this one is the female, and the larger organs are either sex organs or eggs or both.   <agreed... ovaries as we see so conspicuously in other shrimp> Both have right claws that are slightly larger than their left ones, though this difference is less pronounced in the smaller one.  Both claws are easily 4x the size of any cleaner shrimps claws I have seen.  They appear to be designed for cutting more than ripping, as they have a very scissor-like shape.  The claws are on arms that seem to be about 80% of the length of the body.  If form truly does follow function they would be a cause for concern except that they haven't caused any problems in the 6 weeks the clam has been in an aquarium.  The eyes are black and since the body is very clear they stand out.  The eyes on the smaller one are less noticeable.  That is, they are smaller than you would expect given the eye size relative to body size on the larger shrimp.  The eyes are not on any kind of stalks, rather they are much like the eyes on the typical Lysmata spp.  The tails also fan out precisely the same as my common cleaner.  The shrimps do not come out at night.  At least they haven't as of yet.  I will stay up again tonight to note their behaviour.  Speaking of behaviour, the shrimp seem to stay close to each other.  Other than that they just confine all of their movements to inside the shell of the clam.   I will continue to observe them and note anything interesting that might pop up as they grow accustomed to the tank, especially in regards to how they treat their clam host.   <again...much thanks here :) > I hope I do not assume too much in trying to give my opinion on the relationship between shrimp and clam.  I know I am by no means qualified. Do you think it is possible that they are not parasites at all, but a symbiotic bond between shrimp and clam?   <I believe it is possible that they are not parasitic, but I would not say they are likely symbiotic. Commensal would be more likely with the shrimp benefiting (secure housing and the clam pumping food laden water across its face <G>> The shrimp could keep the gills picked clean, and in return the clam protects them inside its shell, which could also allow them a safe place to breed.  A very basic and from what I have read common type of relationship.   <OK> I am by no means a biologist (in fact an historian and musician), but this seems like a probable hypothesis, no?   <perhaps> I just think that if the shrimp were parasitic and chose to, they could easily devour bits of flesh much faster than the clam could hope to regenerate them.   <Hmmm... not exactly... another example in contrast is the Pearlfish that lives within the anus  of sea cucumbers and grazes the innards without killing its host> Especially considering their claw size.   <actually... that would be an argument against symbiosis... form follows function, so if the claws are large but not needed to prey on the clam, they must be used for something- really more likely as originally postulated (Knop and others) that this shrimp at least supplements its diet with other food beyond grooming gills> Unless they are conscientious parasites...  maybe they took ethics courses in Le universite de shrimp?  <G> <heehee... indeed, like the Pearlfishes <G>> Well, I hope that helps.  Pictures will be forthcoming as soon as I can get them to you! RVM <very helpful and thought-provoking! Thank you.. we'll look forward to pics. Very fascinating stuff here. Anthony>



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