Data PolicyPublications | Persons | Institutes | Projects IMIS Photogallery » References Echinothurioida (oral primary spines) Description Points of echinothurioid spines: Oral primary spines serving for locomotion: Left: Phormosoma bursarium: with a distally inflated skin sheath. Right: Araeosoma violaceum: with a hoof.No scale provided. Author Mortensen, Theodor JPG file - 155.61 kB - 1 200 x 1 719 pixels added on 2011-02-23513 viewsFrom reference Schultz, H. (2011). Sea urchins III: Worldwide regular de... © 2011 Mortensen, Theodor Click here to return to the thumbnails overview