Below are examples of jellyfishes you might find washed up on northern Oregon beaches. This isn’t an exhaustive accounting; just the ones I’ve come across and have photos of. As for identification, you can get close on the identifications with the readily available field guides and online resources (see References, at the bottom of the page). I provide alternatives to the photos you’ll find in the field guides and online sources, and natural history notes if I can think of something that hasn’t already been said.
The organization more or less follows Lamb and Hanby (2005). Common names are my choice; usually some combination of those in Lamb and Hanby (2005), and Harbo (2011). I refer to WoRMS for scientific names, and I learn a ton by browsing the natural history riches in Kozloff (1993). All photos are from northern Oregon unless otherwise noted in the caption.
Lion’s mane jellyfish, Cyanea capillata – Lions mane’s aren’t common in the northern Oregon drift line; I can’t say I’ve encountered more than a few fragments there. The one below is from the quieter waters of the Gulf Islands, BC, Canada, where I have seen several in September. Look for an eight-lobed bell.
Fried egg jellyfish, Phacellophora camtschatica – I don’t come across fried egg jellies often. I’m pretty sure these are fried eggs, so I’ll stick with that unless somebody comes up with an alternative interpretation.
Sea nettle, Chrysaora sp. – Sea nettles are one of the most common large jellies washed up on northern Oregon beaches.
Purple-striped jellyfish, Chrysaora sp. – An uncommon find in the northern Oregon drift line, purple striped jellies normally have a limited range around Monterey Bay, California. I came across a couple near Cannon Beach, Oregon in the spring of 2017
Moon jelly, Aurelia sp. – Moon jellies, along with sea nettles (above), are one of the most common large jellies washed up on northern Oregon beaches.
More images of moon jellies in the drift line can be found in Red-eyed medusa, Polyorchis penicillatus. I included a video of live moon jellies at the Tennessee Aquarium in Aequorea and Other Tennessee Jellies.
Water jelly, Aequorea sp. – I don’t notice complete Aequorea too often. They are common, but being thing and transparent, they are easy to overlook. This one is only about 3″ (7.6 cm) across. I floated this one in a finger bowl to get a better look.
Aequorea and some random jellyfish talk (even a moon jelly video) are featured in Aequorea and Other Tennessee Jellies.
Red-eye medusa, probably Polyorchis penicillatus – Little red-eyes can be common in the drift line. To get a good view, float them in a finger bowl. Or, be creative and float it in the bottom of an upside down half-pint canning jar.
By-the-wind sailor, Velella velella – Look for springtime Velella beachcasts. Among freshly stranded Velella look for blue buoy barnacles, and maybe even tiny Janthina, a violet colored ocean-drifting snail.
Note: If you like cnidarians, you might also want to take a look at my Sea Anemone page.
Harbo, R. M. 2011. Whelks to Whales: Coastal Marine Life of the Pacific Northwest. 2nd ed. Harbour Publishing Co.
Kozloff, E. N. 1993. Seashore Life of the Northern Pacific Coast. 3rd ed. University of Washington Press.
Lamb, A. and B. P. Hanby. 2005. Marine Life of the Pacific Northwest. Harbour Publishing.
Sept. J. D. 2009. The Beachcomber’s Guide to Seashore Life in the Pacific Northwest. Revised ed. Harbour Publishing.
Biodiversity of the Central Coast’s Cnidarians and Ctenophores