| Lucinidae Temporal range: Silurian – Present | |
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| Divaricella huttoniana | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Bivalvia |
| Order: | Lucinida |
| Superfamily: | Lucinoidea |
| Family: | Lucinidae Fleming, 1828 |
| Genera | |
See text. | |
Lucinidae, common name hatchet shells, is a family of saltwater clams, marine bivalve molluscs.
These bivalves are remarkable for their endosymbiosis with sulphide-oxidizing bacteria. [1]
The members of this family have a worldwide distribution. They are found in muddy sand or gravel at or below low tide mark. But they can also be found at bathyal depths. They have characteristically rounded shells with forward-facing projections. The shell is predominantly white and buff and is often thin-shelled. The shells are equivalve with unequal sides. The umbones (the apical part of each valve) are just anterior to mid-line. The adductor scars are unequal: the anterior are narrower and somewhat longer than the posterior. They are partly or largely separated from the pallial line. The valves are flattened and etched with concentric or radial rings. Each valve bears two cardinal and two plate-like lateral teeth. These molluscs do not have siphons but the extremely long foot makes a channel which is then lined with slime and serves for the intake and expulsion of water. The ligament is external and is often deeply inset. The pallial line lacks a sinus. [2]
An Eocene species Superlucina megameris was the largest lucinid ever recorded, with shell size up to 31.1 centimetres (12.2 in) high, over 28 centimetres (11 in) wide and 8.6 centimetres (3.4 in) thick. [3]
Lucinids host their sulfur-oxidizing symbionts in specialized gill cells called bacteriocytes. [4] Lucinids are burrowing bivalves that live in environments with sulfide-rich sediments. [5] The bivalve will pump sulfide-rich water over its gills from the inhalant siphon in order to provide symbionts with sulfur and oxygen. [5] The endosymbionts then use these substrates to fix carbon into organic compounds, which are then transferred to the host as nutrients. [6] During periods of starvation, lucinids may harvest and digest their symbionts as food. [6]
Symbionts are acquired via phagocytosis of bacteria by bacterioctyes. [7] Symbiont transmission occurs horizontally, where juvenile lucinids are aposymbiotic and acquire their symbionts from the environment in each generation. [8] Lucinids maintain their symbiont population by reacquiring sulfur-oxidizing bacteria throughout their lifetime. [9] Although process of symbiont acquisition is not entirely characterized, it likely involves the use of the binding protein, codakine, isolated from the lucinid bivalve, Codakia orbicularis. [10] It is also known that symbionts do not replicate within bacteriocytes because of inhibition by the host. However, this mechanism is not well understood. [9]
Lucinid bivalves originated in the Silurian; however, they did not diversify until the late Cretaceous, along with the evolution of seagrass meadows and mangrove swamps. [11] Lucinids were able to colonize these sulfide rich sediments because they already maintained a population of sulfide-oxidizing symbionts. In modern environments, seagrass, lucinid bivalves, and the sulfur-oxidizing symbionts constitute a three-way symbiosis. Because of the lack of oxygen in coastal marine sediments, dense seagrass meadows produce sulfide-rich sediments by trapping organic matter that is later decomposed by sulfate-reducing bacteria. [12] The lucinid-symbiont holobiont removes toxic sulfide from the sediment, and the seagrass roots provide oxygen to the bivalve-symbiont system. [12]
The symbionts from at least two species of lucinid clams, Codakia orbicularis and Loripes lucinalis, are able to fix nitrogen gas into organic nitrogen. [13] [14]
The following genera are recognised in the family Lucinidae: [15]
The Veneridae or venerids, common name: Venus clams, are a very large family of minute to large, saltwater clams, marine bivalve molluscs. Over 500 living species of venerid bivalves are known, most of which are edible, and many of which are exploited as food sources.
Mactridae, common name the trough shells or duck clams, is a family of saltwater clams, marine bivalve mollusks in the order Venerida.
Solemyidae is a family of saltwater clams, marine protobranch bivalve mollusks in the order Solemyida.
Vesicomyidae is a family of saltwater clams, marine bivalve molluscs in the superfamily Glossoidea.
Codakia orbicularis, or the tiger lucine, is a species of bivalve mollusc in the family Lucinidae. It can be found along the Atlantic coast of North America, ranging from Florida to the West Indies.
Ctena orbiculata, commonly known as the dwarf tiger lucine, is a species of bivalve mollusc in the family Lucinidae. It can be found along the Atlantic coast of North America, ranging from North Carolina to the West Indies.
Codakia is a genus of saltwater clams, marine bivalve molluscs in the family Lucinidae.
In ecology, sulfide intrusion refers to an excess of sulfide molecules (S2-) in the soil that interfere with plant growth, often seagrass.
Stewartia floridana is a bivalve of the family Lucinidae that is chemosymbiotic with sulfur-oxidizing bacteria.
Lucina is a genus of saltwater clams, marine bivalve molluscs.
Codakia distinguenda, the elegant lucine, is a species of marine bivalve mollusc. It was first described to science in 1872 by George Washington Tryon Jr.
Radiolucina is a genus of bivalves belonging to the family Lucinidae.
Lucinisca is a genus of saltwater clams, marine bivalve molluscs in the subfamily Lucininae of the family Lucinidae.
Pleurolucina is a genus of saltwater clams, marine bivalve molluscs in the subfamily Lucininae of the family Lucinidae.
Lucinoma is a genus of saltwater clams, marine bivalve molluscs in the subfamily Codakiinae of the family Lucinidae.
Phacoides is a genus of bivalves belonging to the family Lucinidae.
Rostrilucina is a genus of bivalves on the subfamily Myrteinae, belonging to the family Lucinidae.
Taylorina is a genus of bivalves on the subfamily Myrteinae, belonging to the family Lucinidae.
Troendleina is a chemosymbiotic bivalve genus in the subfamily Lucininae of the family Lucinidae.
Wallucina is a chemosymbiotic bivalve genus in the subfamily Lucininae of the family Lucinidae.
| Authority control databases: National |
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