A moon jellyfish swims in Gastineau Channel on Thursday, Sept. 5, 2019. (Michael Penn | Juneau Empire)

A moon jellyfish swims in Gastineau Channel on Thursday, Sept. 5, 2019. (Michael Penn | Juneau Empire)

Seeing lots of jellyfish around Juneau? Here’s why.

Reports of peanutbutterfish are uncomfirmed at this time.

An unusually warm ocean temperature has contributed to a larger-than-usual amount of Aurelia aurita, or moon jellyfish, floating around the waters of Juneau.

Plentiful food in the form of zooplankton, and warm waters are contributing to anecdotally increased numbers of moon jellyfish sightings, said Dr. Sherry Tamone, a professor of marine biology at the University of Alaska Southeast.

Jellyfish spawn freely into the water column, releasing sperm and eggs that fertilize on their own, independent of the parent jellyfish. Spawning in early spring, they’ve reached maturity by now, hence their distinct visibility in the channels and harbors.

“They have two different stages in their life,” Tamone said. “One is attached to the dock or a rock, and one is free floating like a jellyfish.”

A jellyfish washes in with high tide at Sandy Beach on Friday, Sept. 27, 2019. (Michael Penn | Juneau Empire)

A jellyfish washes in with high tide at Sandy Beach on Friday, Sept. 27, 2019. (Michael Penn | Juneau Empire)

All jellyfish have nematocysts that allow them to sting prey and defend themselves, although the sting of the moon jellyfish is considered less painful than the sting of some others, such as the Man o’ War or sea nettles native to the Atlantic Ocean. The moon jellyfish doesn’t have stingers on top of the bell, or head, of the jellyfish.

“If you see them on the beach, just leave them,” Tamone said. “Don’t try and pick them up, or you may irritate your hand.”

Jellyfish are difficult to keep alive in an aquarium environment, Tamone said, as they rely on ocean currents for oxygen and nutrients. Jellyfish typically rely on animal larvae and zooplankton for sustenance.

“They use their stinging cells to eat a lot of larvae in the water column,” Tamone said.

There are concerns that too many jellyfish in the water would eat too many zooplankton, throwing off the ecosystem, but Tamone says that isn’t the case here.

Tamone said lion’s mane jellyfish are also common in northern waters, characterized by their colorful tentacles trailing from the head of the jellyfish.

Tamone recommends watching the jellyfish from a pier, for the best views.

• Contact reporter Michael S. Lockett at 523-2271 or mlockett@juneauempire.com.

More in News

Michael Penn / Juneau Empire File
The Aurora Borealis glows over the Mendenhall Glacier in 2014.
Aurora Forecast

Forecasts from the University of Alaska Fairbanks’ Geophysical Institute for the week of March. 19

Gov. Mike Dunleavy discusses his proposed budget for the 2024 fiscal year during a press conference at the Alaska State Capitol in December 2022. A lower-than-expected revenue forecast is raising questions about what the state's spending plan will ultimately look like. (Mark Sabbatini / Juneau Empire File)
Lower revenue forecast increases budget woes for state lawmakers

Coming up with a spending plan for next year and beyond will be a complex series of negotiations.

Office Max at the Nugget Mall in the Mendenhall Valley advertised Permanent Fund dividend sales in July 2020. Alaskans have until the end of the month to apply for the PFD. (Peter Segall / Juneau Empire File)
PFD application deadline is next week

Amount in flux as state revenue forecasts lower than expected.

This is a photo of the current site plan of the proposed Capital Civic Center. On Monday night the Assembly authorized $5 million to go toward the project that is expected to cost $75 million. (City and Borough of Juneau)
City OKs $5M toward proposed Capital Civic Center

The money is intended to show the city’s commitment to the project as it seeks federal funding

(Michael Penn / Juneau Empire File)
Police calls for Tuesday, March 21, 2023

This report contains information from law enforcement and public safety agencies.

This September 2015, photo provided by NOAA Fisheries shows an aerial view of adult female Southern Resident killer whale (J16) swimming with her calf (J50). New research suggests that inbreeding may be a key reason that the Pacific Northwest’s endangered population of killer whales has failed to recover despite decades of conservation efforts. The so-called “southern resident” population of orcas stands at 73 whales. That’s just two more than in 1971, after scores of the whales were captured for display in marine theme parks around the world. (NOAA Fisheries / Vancouver Aquarium)
The big problem for endangered orcas? Inbreeding

Southern resident killer whales haven’t regularly interbred with other populations in 30 generations.

Juneau Brass Quintet co-founding member Bill Paulick along with Stephen Young performs “Shepherd’s Hey” to a packed house at the Alaska State Museum on Saturday as part of the quintet’s season-ending performance. Friends of the Alaska State Library, Archives and Museum sponsored the event with proceeds going to the musicians and FoSLAM. (Jonson Kuhn / Juneau Empire)
Top brass turns out for event at State Museum

Free performance puts a capt on a busy season.

Alaska’s state legislators are slated to get the equivalent of 6,720 additional $5 bills in their salary next year via a $33,600 raise to a total of $84,000 due to a veto Monday by Gov. Mike Dunleavy of bill rejecting raises for legislative and executive branch employees. (AP Photo/Ted Shaffrey, File)
Veto negates rejection of pay hikes for governor, legislators

Dunleavy clears way for 67% hike in legislative pay, 20% in his to take effect in coming months

Most Read