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Clams as part of the filter system
- Thread starter dz6t
- Start date
Joel A
Started over.
i don't think unless there are mass amounts of them in a small system that they do enough to notice anything..
let's remember that their are different kinds of clams.. the ones we all know and love which are the tridacna family of clams which are photosynthetic and filter feeders... filter feeders for the most part feed off of living things in the water column like microscopic plankton.. so i'm going to assume that they don't do much at all for water quality.
The clams that are sometimes seen sold in clean up crews on the other hand are different, they move throughout the sandbed, and are not photosynthetic. They too are filter feeders as far as i know, and i don't believe they are detritivores, (could be wrong on that though).... so i would tend to say although these clams affect water quality more, they still don't do very much..
just my opinion of course..
let's remember that their are different kinds of clams.. the ones we all know and love which are the tridacna family of clams which are photosynthetic and filter feeders... filter feeders for the most part feed off of living things in the water column like microscopic plankton.. so i'm going to assume that they don't do much at all for water quality.
The clams that are sometimes seen sold in clean up crews on the other hand are different, they move throughout the sandbed, and are not photosynthetic. They too are filter feeders as far as i know, and i don't believe they are detritivores, (could be wrong on that though).... so i would tend to say although these clams affect water quality more, they still don't do very much..
just my opinion of course..
fishindude
The Fish Meister
I think I read somewhere that they have little affect on water quality as well. It might have been here...
Here's some good info...http://animal-world.com/encyclo/reef/clams/tridacna.htm
Nutrition - Feeding
Most clams fulfill their nutritional requirements by, among others, filter feeding and absorbing dissolved organic compounds from the water. Tridacnid clams have gone further than this by using zooxanthellae to manufacture food for themselves.The zooxanthellae are located within zooxanthellal tubules. The tubules extend from the stomach into the mantle tissue. This is different from corals who's zooxanthellae are located within individual cells. The zooxanthellae (through photosynthesis) provide clams with the same products corals receive. The zooxanthellae transforms carbon dioxide and dissolved nitrogen, such as ammonium, into carbohydrates and other nutrients for their hosts. Some other nutrients the clams receive from the zooxanthellae are: carbon (in the form of glucose) and amino acids like alanine. Research has shown that glucose is the primary carbohydrate released by the zooxanthellae to the clam, followed by a group of glucose-based oligosaccharides, then glutamate, aspartate, succinate, alanine, and glycerol.With sufficient light, the zooxanthellae can provide all the respiratory carbon requirements of a clam. The zooxanthellae in return use the nitrogenous wastes of the clam (mostly ammonia) as a nitrogen source. The tridacnids benefit greatly from this system because it allows them to use a very efficient internal food source. The recycling of nutrients between clam and zooxanthellae minimizes energy loss between trophic levels.Tridacnid kidneys contain large amounts of calcium phosphate. The role of this phosphate is unknown. These deposits are also found in clams without zooxanthellae.The mantle also absorbs dissolved nutrients directly from seawater. When exposed to light, the zooxanthellae in the mantle will take in ammonia, nitrate, phosphate and sulfate from the water and use them to make amino acids. This explains why tridacnid clams are able to lower these substances within closed systems, such as your home aquarium. Depending on their need to eliminate excess ammonia, the clams can also expand and contract the mantle to adjust for light intensity changes.It has been shown that additions of ammonia, nitrate and ammonium (mostly in the form of ammonium nitrate) to breeding (culture) systems has improved the growth of juvenile tridacnid clams. These breeding systems were open systems. Unlike our home aquariums, these systems received a constant supply of nutrient poor seawater. Additions of these substances are not necessary to the home aquarium where nutrients are generally many, many times (10 to 100 according to The Reef Aquarium Volume One) higher than seawater.Studies noted in The Reef Aquarium Volume One on feeding and growth of tridacnids show the following:
Filter feeding of particulate organic matter alone in T. gigas can meet 64% of the carbon requirements of 4.2 cm specimens. This percentage declines to 34% in 16.7 cm specimens.
T. derasa and T. tevoroa could easily gain their carbon requirements from zooxanthellae alone.
T. gigas' growth rate and large size may be reached because of its ability to use both autotrophic and heterotrophic feeding. Using both feeding methods means more carbon is produced which means more carbon can be used for growth because the clam's respiration needs are also being met.The role of phytoplankton in tridacnid nutrition is not understood. Although it is believed that phytoplankton provides the clam with some protein, it may be just a carbohydrate source. It is unlikely that there is enough phytoplankton on the reef to meet the clam's needs.It is believed by some that clams must be fed. Especially since clams have feeding appendages like gills, palps, and a digestive system. The gills are required for respiration, ammonia expulsion, and possibly the intake of nitrate. The palps are greatly reduced and the digestive system is used to expel excess zooxanthellae.Zooxanthellae can produce more oxygen than is required by the clam. High levels of oxygen can be lethal and must be eliminated, either through the mantle or, maybe, the gills.There is speculation that tridacnids digest the older zooxanthellae as a source of protein but studies have shown that much of the zooxanthellae found in the stomach, rectum, and feces of tridacnids is still alive and fully functional. Zooxanthellae is usually resistant to digestion so this is not surprising. Clams obtain their zooxanthellae when they are juveniles. The zooxanthellae is introduced through the feeding organs and move from the stomach to the mantle through the tubule system. If the zooxanthellae weren't resistant to digestion, it would never make it to the mantle. Clams have been known, especially after being stressed, to release thin, brown strands from the exhalent siphon. Microscopic examination of the strands reveals viable zooxanthellae. According to The Reef Aquarium Volume One, it is possible to cultivate this expelled zooxanthellae which would prove useful to those considering breeding tridacnids. No other information was provided on how you would cultivate the zooxanthellae
Nutrition - Feeding
Most clams fulfill their nutritional requirements by, among others, filter feeding and absorbing dissolved organic compounds from the water. Tridacnid clams have gone further than this by using zooxanthellae to manufacture food for themselves.The zooxanthellae are located within zooxanthellal tubules. The tubules extend from the stomach into the mantle tissue. This is different from corals who's zooxanthellae are located within individual cells. The zooxanthellae (through photosynthesis) provide clams with the same products corals receive. The zooxanthellae transforms carbon dioxide and dissolved nitrogen, such as ammonium, into carbohydrates and other nutrients for their hosts. Some other nutrients the clams receive from the zooxanthellae are: carbon (in the form of glucose) and amino acids like alanine. Research has shown that glucose is the primary carbohydrate released by the zooxanthellae to the clam, followed by a group of glucose-based oligosaccharides, then glutamate, aspartate, succinate, alanine, and glycerol.With sufficient light, the zooxanthellae can provide all the respiratory carbon requirements of a clam. The zooxanthellae in return use the nitrogenous wastes of the clam (mostly ammonia) as a nitrogen source. The tridacnids benefit greatly from this system because it allows them to use a very efficient internal food source. The recycling of nutrients between clam and zooxanthellae minimizes energy loss between trophic levels.Tridacnid kidneys contain large amounts of calcium phosphate. The role of this phosphate is unknown. These deposits are also found in clams without zooxanthellae.The mantle also absorbs dissolved nutrients directly from seawater. When exposed to light, the zooxanthellae in the mantle will take in ammonia, nitrate, phosphate and sulfate from the water and use them to make amino acids. This explains why tridacnid clams are able to lower these substances within closed systems, such as your home aquarium. Depending on their need to eliminate excess ammonia, the clams can also expand and contract the mantle to adjust for light intensity changes.It has been shown that additions of ammonia, nitrate and ammonium (mostly in the form of ammonium nitrate) to breeding (culture) systems has improved the growth of juvenile tridacnid clams. These breeding systems were open systems. Unlike our home aquariums, these systems received a constant supply of nutrient poor seawater. Additions of these substances are not necessary to the home aquarium where nutrients are generally many, many times (10 to 100 according to The Reef Aquarium Volume One) higher than seawater.Studies noted in The Reef Aquarium Volume One on feeding and growth of tridacnids show the following:
Filter feeding of particulate organic matter alone in T. gigas can meet 64% of the carbon requirements of 4.2 cm specimens. This percentage declines to 34% in 16.7 cm specimens.
T. derasa and T. tevoroa could easily gain their carbon requirements from zooxanthellae alone.
T. gigas' growth rate and large size may be reached because of its ability to use both autotrophic and heterotrophic feeding. Using both feeding methods means more carbon is produced which means more carbon can be used for growth because the clam's respiration needs are also being met.The role of phytoplankton in tridacnid nutrition is not understood. Although it is believed that phytoplankton provides the clam with some protein, it may be just a carbohydrate source. It is unlikely that there is enough phytoplankton on the reef to meet the clam's needs.It is believed by some that clams must be fed. Especially since clams have feeding appendages like gills, palps, and a digestive system. The gills are required for respiration, ammonia expulsion, and possibly the intake of nitrate. The palps are greatly reduced and the digestive system is used to expel excess zooxanthellae.Zooxanthellae can produce more oxygen than is required by the clam. High levels of oxygen can be lethal and must be eliminated, either through the mantle or, maybe, the gills.There is speculation that tridacnids digest the older zooxanthellae as a source of protein but studies have shown that much of the zooxanthellae found in the stomach, rectum, and feces of tridacnids is still alive and fully functional. Zooxanthellae is usually resistant to digestion so this is not surprising. Clams obtain their zooxanthellae when they are juveniles. The zooxanthellae is introduced through the feeding organs and move from the stomach to the mantle through the tubule system. If the zooxanthellae weren't resistant to digestion, it would never make it to the mantle. Clams have been known, especially after being stressed, to release thin, brown strands from the exhalent siphon. Microscopic examination of the strands reveals viable zooxanthellae. According to The Reef Aquarium Volume One, it is possible to cultivate this expelled zooxanthellae which would prove useful to those considering breeding tridacnids. No other information was provided on how you would cultivate the zooxanthellae
OP
OP
that is interesting, does it move around or dig into the sand bed?
I have 8 clams in my 400g system, and my perception is that they do help lower nutrients in the water. I also like the pretty greens, blues, purples and golds. 
I'll also say that I had no success in keeping them until after my system was over 1 year old, but YMMV....
I'll also say that I had no success in keeping them until after my system was over 1 year old, but YMMV....
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