Who in town carries Clams this time of year.

[arkight]

nice looking clams you have there

[reefsavers]

Thank you sir.

Tridacna maxima are not difficult to keep if you meet their basic requirements. I would state what the requirements are, but i figure some people reading this would only come on and challenge my every word. My suggestion would be to read Fossa and Nilsen "Modern Coral Reef Aquarium" or Daniel Knop's book on giant clams.

We will be displaying many of these clams at Macna, and some of my customers(retailers) will be there selling some. Most likely i will donate some to the raffle; if one of the mods is reading this contact me so i can arrange something. Until then, here are some more!
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[sclerite]

You know, the interesting thing about this topic was brought up by Nick and Sue - the lighting "requirements." As far as I know, no one has determined lighting "requirements" for tridacnids. The haemolymph, Z-tubes, nutrient environment, flow regimes, irradiance, genetics and other information regarding contribution of various factors to growth, energy, and distribution has been studied in various species. Rarely are papers found that compare any particular aspect of all species of the genus Tridacna.

It is commonly stated in the hobby that T. crocea and T. maxima "need the most light." I have always wanted to know the source of that statement, because with the exception of T. tevoroa which is the most phylogenetically distant (along with H, porcellanus) and also adapted to lower light levels, all Tridacna and Hippopus species are found in shallow water less that 20m. T. maxima probably has the broadest distribution.

But T. gigas....it gets big and they all have zooxanthellae. So, if you look at contributions of light and particulate feeding, one finds this for T. gigas

Nutrition of the giant clam Tridacna gigas (L.). 1. Contribution of filter feeding and photosynthates to respiration and growth.
Klumpp, DW; Bayne, BL; Hawkins, AJS
Journal of Experimental Marine Biology and Ecology. Vol. 155, no. 1, pp. 105-122. 1992.

The total carbon requirements (growth + respiration) of the host tissues of the giant clam Tridacna gigas from Davies Reef on the Great Barrier Reef were measured, and compared with rates with which nutrients were acquired from the two potential sources, translocated photosynthates and filter feeding. The giant clam is an efficient utilizer of particulate organic matter available in reef waters, retaining on average 75% of particles between 2 and 50 mu m, and absorbing from them 54% of C. The proportion of carbon deposited in tissues relative to that respired is high in giant clams relative to completely heterotrophic bivalves. We conclude that autotrophy is the major source of carbon to this clam, potentially capable of satisfying all respiratory requirements of the host. However, the potential importance of heterotrophy to total energy needs of the host is also significant and changes with the size of clam. The spectacular rates of growth in this clam are such that filter feeding is able to provide 65% of the total carbon needed both for respiration and growth in small clams (100 mg dry tissue wt), whereas large clams (10 g) acquire only 34% of their carbon from this source.

and interestingly, from MEPS(137): 139-47

Relationships between size, mantle area and zooxanthellae numbers in five species of giant clam (Tridacnidae)

Griffiths CL, Klumpp DW
Relationships between body size and both projected mantle area and numbers of symbiotic zooxanthellae were calculated for 5 species of giant clam from the Great Barrier Reef. Parameters were closely correlated in all species, but the allometry of the relationships differed markedly between clam species. Mantle areas were consistently lowest in Tridacna derasa. T. crocea and Hippopus hippopus had the largest mantles at small body size (2 cm), but because of slow length-related increments were soon overtaken by T. gigas and T. squamosa, the latter developing a mantle area double that of other species at 30 cm length. Similar allometric variations were evident in zooxanthellae numbers. At small size these were much lower in T. squamosa and T. gigas than in H. hippopus,T. crocea or especially T. derasa; but by 30 cm length T. squamosa and T. gigas had the largest zooxanthellae populations. When expressed per unit body mass zooxanthellae numbers declined rapidly with size in all species. The rate of decline was most marked in T. crocea, this being a function of its rapid length-related increment in flesh mass. This is probably the main factor restricting T. crocea to small terminal body size. By contrast, rapid length-related increments in mantle area and zooxanthellae numbers in both T. gigas and T. squamosa appear to favour the large body size and rapid growth observed in these species. The reason why T. squamosa is unable to realize the rapid growth and enormous terminal size observed in T. gigas is obscure, but may be a function of the relative reproductive output of these species, which remains unquantified.

So, although I cannot find any quantification of light requirements, it appears as though zooxanthellae densities (probably correlated with "light requirements") vary according to species and size and T. crocea zooxanthellae density declines most rapidly with size.

It is generally found that T. crocea and maxima are among the more sensitive species in captivity, but whether this is due to light requirements or other factors, I do not believe, has been determined. Also, the availability, and hence reporting, will be greatest for those species most common in trade, and those are generally the more colorful varieties that command higher prices...i.e. T. maxima and T. crocea. The majority of larger clams or non-colorful clams go to the food trade, so without any quantification other than articles involved in aquaculture (in situ), I think we have really very little knowledge of what each species "requires" or why one species tends to be hardier than others, if in fact there is a difference at all.

[maggiesaqsup]

lots of good info here.

aqua pod

I have two 1 1/2 to 2" left at a good price $25.00 let me know if you want one. I will be ordering more in a few weeks.We are going on vacation next week and will place an order when we get back. If they are not the color you want let me know and I will try to get the color you want.There is not many places that sell them at this price .They are cultured from Tonga.I have had better luck with them than I did with any other wholesalers clams.

[SueT]

the info I use is from Daniel Knop's Giant Clams, Reef Invertebrates by Bob Fenner and what Barry Neigut of Clamsdirect has been saying for years now.

[sclerite]

Hi Sue: Right....that's where most of our hobby information comes from on these bivalves...along with the original "Reef Aquarium, Vol. 1". James Fatheree has a new book coming out on clams, too.

I don't make it a point to exhaustively scour the literature for Tridacna articles, but do read them whenever I find them, and I did about an hour or so of literature searching before posting and I cannot find anything to support those works and the books you mention do not have pertinent references for that information either, nor do the references in Sprung and Delbeek apply to this question. So, I think it is anecdotal and probably untrue given the energy requirements of the larger species.
It even makes logical anecdotal sense based on the articles of Klumpp et al. that T. gigas, due to its size and zoox densities, is probably the most "needy" of both light and food.

T. crocea are found burrowed in rock and do not really extend their mantles very far, and thus one could make an assumption that this exposes relatively fewer zoox to light meaning they either need less energy from light or are somehow able to capture more effecively or their small terminal size limits their energy needs to existing effective light capture means. T. maxima are common to 45-60 feet, the lower limits for clams, and have broad mantle extension but are also retractile, allowing for potentially greater modulation of light reaching zoox, like corals that can expand or contract to moderate the irradiance reaching zoox, so they may be more flexible. These statements are just speculative on my part, I think, but make sense when the existing literature and their habitats and behaviors are considered.

[SueT]

another source of info that comes directly from us reef/clam enthusiasts are those that daily post to Barrys Clamsdirect forums asking why their crocea clam is not thriving and upon asking tank environments say "well, I'm keeping it under pc or vho lighting". Adding halide lighting and the problem seems to be solved. That is if the clam was even saved.

I'm only going by what we are asked daily and several times daily for that matter on Barrys forum and what Barry suggets as he has seemed to be the only one in the last few years doing so much research on these wonderful creatures.

[sclerite]

Oh, I understand. But, if you look back to 1994, you'll find that people were successfully keeping these species under even NO fluorescents though admitted that brighter light helped, of course. And, perhaps the increase in lighting was supplementing energy not otherwise available from particulate feeding and that the clams in question were of a size class for the species where light played a larger role. And, it also goes back to the number of reports and availability of species, individual tank differences, husbandry, and substituting one energy source for a deficit of another natural source, not necessarily light requirements or limitations.

[Style23]

i was at city pets yesterday and they had 4-5 blue/purple ones about 3" for $40

[aquapod]

Sorry I havent logged on to the forum in a while. Hey maggie I picked one up at city pets last week. But I want another one. I am new to the forum. Do you own a store or something? Sorry but I would love to come pick up another clam soon. Let me know!

[maggiesaqsup]