11. Rarely found above depths of, sea pens prefer deeper waters where turbulence is less likely to uproot them. 12. Certain starfish ochre sea star ( " Pisaster ochraceus " ), which does not feed on sea pens . 13. Octocorallia comprises the sea pens ( Pennatulacea ), soft corals ( Alcyonacea ), and blue coral ( Helioporacea ). 14. Sea pens are grouped with the octocorals ( " soft corals " ), together with sea whips or gorgonians.15. Sea pens are sometimes brightly coloured; the orange sea pen ( " Ptilosarcus gurneyi " ) is a notable example.16. Sea pens are sometimes brightly coloured; the orange sea pen ( " Ptilosarcus gurneyi " ) is a notable example. 17. Contributing factors are an ambient water temperature above 16 degrees Celsius, crowding and poor water circulation inside the sea pens . 18. They position themselves favourably in the path of currents, ensuring a steady flow of plankton, the sea pens 'chief source of food. 19. In contrast to sea pens , which grow by basal insertion, " Charnia " grew by the apical insertion of new buds. 20. From 1992 to 1999 the aquarium hosted a family of dolphins enclosed in a sea pen , which later died due to poisoning.
