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Squamosa Clam - Tridacna squamosa

Scaled Clam, Fluted Clam, Scaly Clam, Fluted Giant Clam

Family: CardiidaeTridacna squamosaPhoto © Animal-World

   Though not as flashy as some of the Tridacna Clams, the Squamosa Clam has a very distinctive and subtle beauty of its own!

   The Squamosa Clam Tridacna squamosa is most commonly found with a brown mantle patterned with many golden brown or yellow wavy lines. One of its most most striking attributes is the contrast on the mantle, created with the dark background accenting the lighter colored spots and wavy lines. The mantle can be high in color with green and blue spotted varieties. They have also occurred with rose and purple coloring.

   The clam shell of the Squamosa Clam is also quite intriguing, with distinctions unique to this Tridacna clam species. The symmetrical shell has large leaf-like fluted scales, call scutes, on its shell. In the wild these scutes provide shelter for other small animals such as little crabs and clams, and other invertebrates.

   Because of its leaf-like scutes, the Squamosa Clam is described by a number of names reflecting its appearance. In fact, the name 'squamosa' is latin meaning 'scale'. Common names include the Scaled Clam, Fluted Clam, Fluted Giant Clam, and Scaly Clam. Aquacultured Squamosa Clams will also be referenced to as the Squamosa Clam Cultured.

Scientific name    Tridacna squamosa

Distribution / Background

   The Squamosa Clam is found in the Indo-Pacific. Its distribution in the wild ranges from East Africa through Polynesia. Tridacna squamosa was first described by Lamarck in 1819.
   The Squamosa Clam's are found in sheltered areas like back-reef lagoons and reef walls. They can be found as deep at 49 - 59 feet (15 - 18 m). Though always attached by their byssus threads, they are usually found lying on the substrate and often amongst Acropora corals. T. squamosa's are sought after by the shell trade and are frequently imported from the Philippines.

Status

   The Tridacna squamosa is listed on the IUCN Red List as LR/cd - Lower Risk/conservation dependent.. It is listed as 'Endangered' on the Red List of threatened animals of Singapore, where it is called the Fluted Giant Clam

Photo © Harbor Aquatics

Description    The Squamosa Clams, also known as Scaly Clam or Fluted Clam, reach a maximum length of 16 inches (40 cm). They are most commonly found with a brown mantle with many golden brown or yellow wavy lines. However, the mantle can also be very variable in coloration and quite beautiful. Accented on a dark background with green and blue spotted varieties, and sometimes rose or purple.

   Characteristics of T. squamosa:

• symmetrical shells
• shells are usually white but can be yellow, orange, or pink
• shell has large, widely spaced scutes
• the hinge is half the shell's length
• the inhalant siphon has many large, branched tentacles
• the mantle extends well over the edges of the shell
• small/medium size byssus gland opening

   Comparing Squamosa Clams to other species of Giant Clams:

• Maxima Clam: Young Squamosa Clams are sometimes confused with the Maxima Clam Tridacna maxima, mostly because both clams have scutes on their shells. The rows of scutes of a Squamosa Clam are much larger and not as close together as on the Maxima Clam, and the hinge on the Maxima is smaller. Also the shell of the Squamosa Clam is symmetrical, while the shell of the Maxima Clam is asymmetrical.
• Crocea Clam: The byssus gland opening on the Squamosa is wide, but not like that of the Crocea Clam Tridacna crocea.

   According to The Reef Aquarium Volume One, Squamosa Clams T. squamosa are known to form hybrids with the Crocea Clam T. crocea and the Maxima Clam T. maxima.

Difficulty of Care

   The Squamosa Clam is not only subtly beautiful, but can be a good choice for a beginning saltwater enthusiast. it is a hardy clam that usually does well in reef aquariums. The T. squamosa can live for more than 10 years in your tank. Unlike the Maxima Clam and the Crocea Clam, the Squamosa Clam's aren't as demanding in the light department, but they also are not as tolerant of strong currents.

Foods / Feeding

   It is generally believed that giant clams do not require feeding in the aquarium. Most clams fulfill their nutritional requirements by filter feeding and absorbing dissolved organic compounds from the water. The Tridacna clams have gone even further than this, using zooxanthellae to manufacture food for themselves. Being primarily photosynthetic, the Squamosa Clam is a highly efficient self-feeder. Though it may benefit from feedings of phytoplankton, it is not required.
   Whether additional feeding of Tridacna Clams is required is still debated. Some enthusiasts believe they should be fed, going on the assumption that they are filter feeders like other clams. If you wish to feed your clam, it is suggested that they be fed micro-foods designed for filter feeders, especially when small. A yeast-based suspension is one suggestion, unless the tank has other fish and corals that are regularly being fed, or you can offer other micro-foods such as phytoplankton or commercially prepared micro-foods like 'marine snow' or 'reef snow'.
  Basic nutrients in the aquarium that the giant clams need are calcium, strontium, iodine, magnesium, and possibly a minute amount nitrate.

• Calcium: Calcium is the main building block for clams and should be present in the water at levels of at least 280 mg/L for growth to occur. More rapid, natural growth is seen when calcium is in the range of 400-480 mg/L.
• Strontium: Strontium is incorporated in the shell along with calcium and should also be provided for optimum growth.
• Iodine: The addition of iodine to the aquarium will also enhance growth and color in giant clams.
• Magnesium: Magnesium aids in maintaining proper calcium levels and in the formation of skeletal material in clams
• Nitrate: They require some nitrogen for proper growth. Nitrate can be added if levels are extremely low, but be careful as nitrates should never exceed 2 mg/L.

   For more information about the feeding process of Squamosa Clams see What Do Clams Eat.

Aquarium Care

   If a healthy clam is obtained, these clams are hardy in captivity and relatively easy to keep. With proper lighting and careful attention, Squamosa Clams require require little else in the way of care. It is important to make sure they are not being irritated, not being fed upon by other organisms, and good water quality must be maintained.

• If you have a healthy specimen, it will generally attach itself to the substrate in less than a day. Keep this in mind when placing your clam in the tank. Make sure you put it where you want it to stay.
• Keep a watch for predators as this clam can be easy prey with its large and wide byssus gland opening.
• Squamosa Clams aren't as demanding in the light department as other Tridacna clams. However they are not as tolerant of strong currents as some of the other giant clams, nor as tolerant of strong fluctuations in water parameters. You really don't want your water parameters to fluctuate too much!
  

Aquarium Parameters

   Squamosa Clams can be kept in a reef environment with live rock. They should be placed on a firm substrate with a a low to moderate water flow. Keep fluctuations in water parameters to a minimum. A high pH and high temperatures can cause problems.

• Lighting:  Coming from deeper waters than some of the other giant clams, these clams will not need as intense lighting. They requires moderate to intense lighting. According to Aquarium Frontiers' On The Half Shell by Daniel Knop, T. squamosa is easily stressed if you put the clam under lighting that is too bright with strong currents and frequently develop central bleaching when under strong lighting.
     If your T. squamosa is wild caught, start by putting it in the lower third of your tank. If the clam doesn't open within a few days, move it into a spot with indirect lighting. .
     If the lighting above your tank is good, place the clam at the bottom of your tank. T. squamosa's can let loose a good, strong blast of water when they slam their shells shut. So, if you put your clam too close to the top of your tank, you'll end up with water up in your lights.
• Temperature: Mid to Upper 70° F. (mid 20° C.). Do not let the aquarium exceed 84° F.
• Salinity / Specific Gravity: 1.024. Salinity is also important, too high or low a salinity can cause the death of a clam. Try to keep specific gravity between 1.023 and 1.025.
• pH: 8.3. Do not let the aquarium exceed a pH above 8.4.
• Hardness: Maintain a dkh of 7.9.
• Water Movement: For the Squamosa Clam, the water current should not be too strong.

For more in depth information on caring for Maxima Clams see, Caring For Tridacnid Clams

Compatibility and Social Behaviors:

   Clams are very stationary and peaceful, they are not aggressive towards other aquarium inhabitants. Though they have the ability to shut completely, they do need protection from anemones and some corals. They should not be kept near any stinging cell creatures and must be kept away from any sweeper tentacles. Anemones need to be watched, as they can move close to a clam and sting or eat it.
   Be cautious with other tank inhabitants as well, those that may pick at the clam or eat its mantle, such as Trigger Fish and Puffers. Blennies, Butterfly Fish, Clown Gobies, Angelfish and shrimp may disturb Tridacna clams.

Breeding and Reproduction

   Squamosa Clams have been propagated in captivity and are often referred to as Squamosa Clam Cultured. The demand from aquarists has raised interest in producing colorful varieties of all the tridacna clam species.

   For detailed information of tridacnid propogation, see Giant Clam Breeding and Reproduction

Potential Problems

   Keep a watch out for predators! The Squamosa Clam can be easy prey with its large and wide byssus gland opening. They are also quite sensitive to chemicals or toxic substances dissolved in the water, so be sure to maintain good water quality. As mentioned under aquarium care and aquarium parameters above, high pH, high salinity, and high temperatures can also cause problems.

  For in depth information on potential Tridacna clam problems, see: Tridacnid Clams: Friends, Enemies & Ailments

Availability

   Clams obtained from aquaculture systems are readily available and are very hardy in reef aquariums.

Authors: Elizabeth M. Lukan / Clarice Brough, CFS.

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