Morphology and Settling Velocity of Sea Stars (Asterias rubens)

This study presents morphological data and estimates of the settling velocity and drag coefficient of sea stars (Asterias rubens) caught in the Limfjord, Denmark. A geometric model describing the sea star is presented and the thickness and arm width are determined as linear functions of arm length. The volume and mass of the sea stars is well predicted by the geometric model and is in agreement with the experimental measurements. The mean sea star density is determined to be 1095 kg/m3, the mean drag coefficient is estimated to be 2.3 and the settling velocity is shown to vary with the square root of the its size.