Identification Key for Common Intertidal Sea Stars of Puget Sound
- Start at 1a.
- Count the arms on the sea star you wish to identify and then click on the appropriate statement. You will be moved to the next appropriate pair of statements.
- Click on the appropriate statement in that pair.
- Repeat this process until your animal is identified.
Start Here- Click either statement 1a or 1b below.
* Two measurements need to be made in order to determine the relative length of the arms of a sea star. Simply stated, a sea star is made up of arms and a central area to which they are attached called the disk. Since a sea star has radial symmetry, their dimensions are referred to radii.
"R" is the length of the arm as measured from the center of the animal to the tip of the arm.
"r" is the radius of the disk and is measured from the center to a notch between the arms.
R divided by r (R/r) is the relative length of the arm.