In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
Q: Each group of bivalves tends to have distinctive hinge teeth .
A: 
Each related group of bivalves tends to have distinctive hinge teeth , and because of this , examining the arrangement of the hinge teeth in a bivalve shell is often essential for identification and classification .