Bivalves occupy a variety of environmental niches living in a variety of ways. Some live in freshwater and brackish environments, but most are marine. Many live as epifaunal, infaunal or nektonic animals, filter feeding by catching particles on grooves on their gills. Bivalves are often preserved with the two valves open or as individual valves... Read more


  • Phylum: Mollusca
  • Class: Bivalvia

Diagnostic features

These are the features that will help you to identify fossils as bivalves, and that you should be attempting to label on a sketch (if they are preserved!).

  • Palial line/palial sinus
  • Adductor muscle scars
  • Growth lines
  • Dorsoventral symmetry (some exceptions, for example Gryphaea)
  • Two valves
  • Umbo
  • Hinge
  • Gills (rarely preserved)

Stratigraphic range

Cambrian to present