| Arcida Temporal range:
| |
|---|---|
| |
| Anadara from the Pliocene of Cyprus. | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Bivalvia |
| Subclass: | Pteriomorphia |
| Order: | Arcida |
| Families | |
|
11, See text. | |
| Synonyms | |
|
Arcoida | |
The Arcida is an extant order of bivalve molluscs.[1] This order dates back to the lower Ordovician period. They are distinguished from related groups, such as the mussels, by having a straight hinge to the shells, and the adductor muscles being of equal size.[2] The duplivincular ligament, taxodont dentition, and a shell microstructure consisting of the outer crossed lamellar and inner complex crossed lamellar layers are defining characters of this order.[3]
Seven families are currently recognised within the order, including the well-known ark clams or ark shells in the family Arcidae.
- ^ Cite error: The named reference
WoRMS_207was invoked but never defined (see the help page). - ^ Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 430. ISBN 978-0-03-056747-6.
- ^ Matsumoto, M. (2003). "Phylogenetic analysis of the subclass Pteriomorphia (Bivalvia) from mtDNA COI sequences". Molecular Phylogenetics and Evolution. 27 (3): 429–440. doi:10.1016/S1055-7903(03)00013-7. PMID 12742748.