Valve Margins - Comparison

 

Valve margin comparison is an important characteristic in the identification of dreissenids. Three comparisons are noted, as follows:

  1. Shell margins are equal to one another, as in Dreissena polymorpha.
  2. One shell margin extends past the other, as in umbonal pediveligers and plantigrade larvae of quagga mussels.
  3. The right valve margin extends past the left, as in quagga pediveligers of all ages.

 

NOTE: In the first two cases, it is very difficult to see these characteristics.

 

image\valamargr.gif

 

Larval Identification Information

Zebra Mussel Identification