Hinge Teeth

Alasmidonta heterodondwarf wedgemussel

Alasmidonta heterodon
dwarf wedgemussel

unique with 2 lateral teeth in the right valve, 1 in the left

Elliptio complanataeastern elliptio

Elliptio complanata
eastern elliptio

sharp, prominent laterals and large pseudocardinals

The hinge "teeth" are small structures of irregular shape and size that hold the two halves of the shell together.
Alasmidonta undulatatriangle floater

Alasmidonta undulata
triangle floater

laterals may be vestigial, with heavy, triangular pseudocardinals

Margaritifera margaritiferaeastern pearlshell

Margaritifera margaritifera
eastern pearlshell

large, conspicuous, triangular pseudocardinals; laterals absent

The principal teeth are the pseudocardinals and the laterals; a few species have a third type, the interdental, that lies between the two.
Lampsilis radiataeastern lampmussel

Lampsilis radiata
eastern lampmussel

laterals may be weak but clearly defined; interdentals present

Strophitus undulatuscreeper

Strophitus undulatus

some species have all teeth poorly defined or absent

Each type of tooth may be absent or vestigial, and their presence, absence and combination can be definitive for species identification.