Ptilosarcus gurneyi (Gray, 1860)
Common name(s): Orange sea pen, fleshy sea pen, sea feather
Subclass Alcyonaria (Octocorallia)
|(Ptilosarcus gurneyi from Rosario Bay. Approximate length 25 cm)|
|(Photo by: Dave Cowles August 2004)|
How to Distinguish from Similar Species: There are no similar species near Rosario.
Geographical Range: Gulf of Alaska to southern California
Depth Range: Shallow subtidal to 70 m
Habitat: Sand and mud bottoms
Biology/Natural History: The entire central
part (rachis) is said to be one large polyp. Smaller, inconspicuous
polyps open into it and pump water in an out as needed for expansion or
contraction. Produces a strong greenish luminescence when disturbed.
Preyed upon by several nudibranchs, including Hermissenda
crassicornis, Armina californica, and Tritonia festiva,
of the seastars Dermasterias imbricata, Pycnopodia helianthoides, Mediaster
aequalis, and Crossaster papposus. The sea pens may rapidly
burrow into the sediment when contacted by a predator. Although they
do not appear to burrow when exposed only to seawater which contained a
predatory seastar, they were more likely to burrow after contacting a predatory
seastar if they had already been exposed to its smell. This species
responds to different predators differently.
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Gotshall and Laurent, 1979
Weightman, Janice O. and David J. Arsenault, 2002. Predator classification by the sea pen Ptilosarcus gurneyi (Cnidaria): role of waterborne chemical cues and physical contact with predatory sea stars. Can. J. Zool./Rev. Can. Zool. 80(1): 185-190 (2002)
In our experience this species is usually found in quieter water such as behind Whidbey Island. Years ago there was a small colony in Rosario bay. The colony disappeared and no individuals were seen for 5-10 years. In the 1980's some students working on a project harvested some individuals from behind Whidbey Island. After the project they returned them to Rosario Bay. Since that time the species has been becoming more abundant in the bay again.
In my experience, if this species is not placed into sand or mud in the aquarium, it usually has a problem with its lower stalk which becomes hyperinflated.
A short video of this species can be found at: http://www.racerocks.com/racerock/archives/vidseapen2a.htm
Another photo. Note that the polyps are arranged in flaplike rows on the plume. Photo by Dave Cowles, July 2005
This closeup shows the individual polyps lining the rows. A small majid crab has climbed aboard, and may be nipping at the polyps, though the crab's activity did not stimulate Ptilosarcus to close.
Buds seem to be growing off 3 of the laminae on the right side of the plume of this individual. Does Ptilosarcus do any budding for reproduction?
Photo by Dave Cowles, July 2005