# Shell Orientation and Measurement

The following diagrams show how to measure length and height of veligers, clam-shaped larvae and juveniles, and mussel-shaped juveniles.

In addition, this picture shows the relationship between the size of immature zebra mussels and other commonly collected organisms.

Notice the size relationship between the dreissenid larvae and other commonly collected planktonic organisms.

For more information on shell measurement see the Shell Length and Height section.