Ark Shells and Allies
Arcida
The Arcoida is an extant order of bivalve molluscs. 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. 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.
2 branches of this order, most-observed first
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Where it lives
Recorded sightings
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geo-referenced records in GBIF, from museums, herbaria and field observers.
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In the stacks
Searching the stacks…
Every page naming Arcida in the Biodiversity Heritage Library →
This page is assembled live from iNaturalist, GBIF, Wikipedia, the Source Library and the Internet Archive. It is not yet part of the hand-edited codex. iNaturalist taxon 85503.