Cnidaria
Sea pens
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Fig. 1.  Sea-pen bed Ptilosarcus gurneyi
Courtesy Nalavade et al. 2025

There are several deep-water species of sea pens on our coast, but only one species Ptilosarcus gurneyi that lives commonly in shallow-water (Fig. 1).  A closely related species is the sea pansy Renilla, but it is more commonly found in warm waters of southern California.

Nalavade et al.   2025   J energy Res Technol Pt A 1 (1):

ANIMATION of the snail's odyssey © Thomas Carefoot 2026
map used by the snail in A SNAIL'S ODYSSEY

To navigate through the ODYSSEY:

  • Select a TOPIC from the menu at the top of the screen
  • OR: play the animation to the left
  • OR: follow the snail's ODYSSEY by CLICKING on any X-marked invertebrate on the map above

Phylum Cnidaria (lit. “nettle-bearing” G.), referring to the nematocysts possessed by all members of the phylum; includes sea anemones, corals, sea pens, gorgonians, jellyfishes, hydroids

Class Anthozoa  (lit. “flower animal” G.), including sea anemones, sea pens, corals, jellyfishes, and cup corals

Subclass Octocorallia (=Alcyonaria) (lit. “eight coral” G.), referring to 8-fold mesenteries and polyp tentacles; mostly colonial animals such as soft corals, gorgonians, and sea pens

Order Pennatulacea (lit. “feather characterised by” L.), including sea pens and sea pansies

Order Alcyonacea (lit. “zoophyte” G.), including soft corals such as Alcyonium spp. and Cryptophyton goddardi

NOTE  the west-coast soft coral commonly known as Gersemia rubiformis is apparently an undescribed specis of Alcyonium

Fautin & Hand   2007   p. 173 In, The Light and Smith manual. Intertidal invertebrates from central California to Oregon (Carlton, ed.) Univ Calif Press, Berkeley