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Related FAQs:  Bivalves, Bivalves 2, & Bivalve Identification, Bivalve Behavior, Bivalve Compatibility, Bivalve Selection, Bivalve Systems, Bivalve Feeding, Bivalve Disease, Bivalve Reproduction, Tridacnids, Tridacnid Clam BusinessTridacnid Identification, Tridacnid Selection, Tridacnid Compatibility, Tridacnid Systems, Tridacnid Lighting, Tridacnid Placement, Tridacnid Feeding, Tridacnid Disease, Tridacnid Reproduction, Flame Scallops,

Related Articles: Mollusks, Giant Clams/Tridacnids

/The Conscientious Marine Aquarist

Bivalves: Clams, Oysters, Mussels... Class Bivalvia, Pt 1 

To: Pt. 2, Pt. 3

By Bob Fenner

Spondylus varians, Fiji


Bivalve Mollusks: Shellfish with two opposing shells that are hinged at one end with an elastic byssal material and brought together with attached muscles. May be attached to hard substrates, burrowed into same or wood, buried in sand, mud or free-living, able to jettison about with powerful discharges of water from their exhalant siphons. 

    Most bivalves are filter-feeders, sifting food through their gills, which also function as respiratory organs. Some notable aquarium species, the giant clams (family Tridacnidae) utilize endosymbiotic algae (zooxanthellae) to produce food through exposing their mantles to bright light.

    About 7,700 species worldwide... Some 129 in Hawaiian waters of which 66 are endemic. 

Ark Shells, Family Archidae: Have a row of fine teeth along the hinge line of their solid ribbed shells. Some attached, others living in sand. Twelve Hawaiian species. 

Arca ventricosa Lamarck 1819, the Ventricose Ark Shell. One of eight species found in HI. Found through-out Indo-Pacific attached to rocks with straight hinge facing outwards. to eighty feet in depth, three inches in length. A dead shell and a live, attached animal off of the Big Island, Hawai'i. 

Oysters, Family Isognomidae:

Isognomon alatus, Flat Tree-Oyster. To 3 in. Roatan 2016. TiffB pic.

Isognomon radiatus, Lister Purse Oyster. To 2.5 in. Often found in clusters. Roatan 2016.

Pen Shells, Family Pinnidae: Winglike, triangular in shape, anchored, pointing with their sharp ends into the soft substrate. 

Atrina pectinata (Linnaeus 1767), the Pen Shell. India to Australia; Indonesia, Philippines, Japan. There are other species called Pen Shells, and some of these make their way into the ornamental trade. Typical appearance in an aquarium, mounted vertically, but the Seastar is not a friend and image in the wild, Maldives showing the dark mantle from a view above.

Family Ostreidae: True Oysters

Dendostea frons, the Frond Oyster. Tropical West Atlantic. To two and a half inches in length. A couple off of St. Lucia attached to an octocoral skeleton, and another off of St. Thomas, U.S.V.I. Note zig-zag interlocking valves.

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Hyotissa hyotis (Linnaeus 1758), the Honeycomb Oyster. Uneven zig-zag openings on shell. South Africa to the Red Sea, out to New Guinea, Indonesia and the Philippines. This group in Pulau Redang, Malaysia, and N. Sulawesi.

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Flame Scallops that are not. Pen Shells, family Limidae: A popular item, particularly Lima scabra out of the Caribbean. Most all of these die in short order from starvation. Need frequent "immersion type" feedings... daily.

Lima (Limaria) scabra (Born 1778), sold as "Flame Scallops" in the aquarium interest, this is aka the Rough Fileclam of the Penshell family Limidae. Can "swim away" if threatened. A beautiful animal that generally starves in captivity due to a lack of food. Aquarium images of not so healthy and healthier specimens, and a real good specimen... in the wild (St. Thomas, U.S.V.I.)
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Limaria fragilis Gmelin 1791, the Fragile File Shell. Indo-Pacific; Red Sea to Japan, Australia. Takes a beating if stocked with many types of fishes, crustaceans. Needs to be inserted in rock cover. Queensland, Australian photo. 

Bigger PIX:
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Limaria orientalis (Adams & Reeves 1850), File Shell. Uniformly Red with thicker tentacles than other Files. Found in sand or between rocks (like here). Western Pacific; New Guinea, Indonesia, Philippines. N. Sulawesi image. 

To: Pt. 2, Pt. 3

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