ABSTRACT
The mode of growth in aboral spine ossicles from adult A. planci, from the GBR is a linear process forming a shaft with a relatively constant diameter along its length. This was demonstrated using tetracycline staining. Growth is recorded by frequent growth episodes producing growth lines parallel to the spine ossicle base and observed in longitudinal thin-sections. Spine growth is apparently less affected by nutrition and age than body diameter. Therefore, it is predicted that old A. planci will possess relatively long spine ossicles.
