Chrysaora fuscensens Brandt, 1835

Common name(s): Sea nettle

Synonyms: Chrysaora helvola, Chrysaora gilberti Chrysaora fuscescens
Phylum Cnidaria 
Class Scyphozoa 
Family Pelagiidae 
Chrysaora fuscescens, up to about 25 cm diameter, photographed at Monterey Bay Aquarium
(Photo by:  Dave Cowles, August 2010)
Description:  This scyphomedusa has an amber-colored bell which is darkest near the margin.  It may have an indistinct, pale star pattern radiating to the margin as well.  It has about 24 tentacles which are long and brown and arise individually between the lappets; with three tentacles between each rhopalium (it has 8 rhopalia).  The oral arms are long and strongly spiraled when contracted, though they may be straight when relaxed (photo).  The oral arms have crenulated edges (photo).   Bell to 30 cm diameter and tentacles/oral arms may reach to 2.4 m.

How to Distinguish from Similar Species:  This is the only similar species likely to be common of the Washington and Oregon coast and the only one with the strongly amber-colored bellChrysaora melanaster is common off Alaska and may occasionally drift this far south.  C. melanaster has a pale, whitish exumbrella with 16 dark brown radiating streaks and the oral arms are not as strongly twisted. Chrysaora colorata (photo) is an oceanic species found mainly south of San Francisco.  Its color is magenta, brown, and blue combining to form a purple pattern on the mainly whitish exumbrella. Many older references confuse our west coast C. fuscescens with C. melanaster.

Geographical Range: Japan, Siberia, northern Alaska to Mexico.  Most common off central California and Oregon, especially common in winter.

Depth Range: Epipelagic

Habitat: Pelagic on the open coast

Biology/Natural History:  This species may form large groups just offshore on the open coast, and many may strand on the beach.  This jellyfish can sting (especially the tentacles) so be careful of contact.  Symptoms may including itching or a rash; or more severe symptoms in those allergic to the sting.

Especially in the open ocean, the small red hyperiid amphipod Hyperia is often found riding on the jellyfish feeding on the tissues.

Large Chrysaora have been observed to feed on medusae, ctenophores, and pelagic worms.  Since the nematocysts sting humans I would presume that they may feed on fish as well.  Predators of the jellyfish include blue rockfish Sebastes mystinus, which avoid the tentacles and bite off pieces of the oral arms.



 

References:

Dichotomous Keys:
  Kozloff, 1987, 1996
  Carlton, 2007

General References:
  Brusca and Brusca, 1978 (as C. melanaster)
  Gotshall, 1994 (As C. melanaster)
  Johnson and Snook, 1955 (As C. gilberti)
  Lamb and Hanby, 2005
  Morris et al., 1980 (As C. melanaster)
  Niesen, 1994 (As C. melanaster)
  Niesen, 1997 (As C. melanaster)
  Wrobel and Mills, 1998

Scientific Articles:
 

Web sites:


General Notes and Observations:  Locations, abundances, unusual behaviors:
 

I do not recall seeing this species in the Salish Sea area, though I may have misidentified stranded individuals as Cyanea capillata lion's mane jellies because of the coloration.  It is primarily found on open coasts.

Uncoiled arms

The ends of the oral arms in this individual have straightened out.  Note the crenulated edges.

Group

Groups of this species can be quite colorful.  Photo at Monterey Bay Aquarium by Dave Cowles, August 2010

In Moss Landing Harbor

This individual was swimming near the surface at the entrance to Moss Landing Harbor, CA.  Photo by Dave Cowles, August 2010



Authors and Editors of Page:
Dave Cowles (2010):  Created original page
CSS coding for page developed by Jonathan Cowles (2007)

Rosario Invertebrates web site provided courtesy of Walla Walla University