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

Sarah Palmer talks to a driver before administering a COVID-19 test in December 2020. On Tuesday, the City and Borough of Juneau reported an uptick in cases identified over the weekend that included Martin Luther King Jr. Day.  However, the community's COVID risk level remains at the moderate level, which was set last week after months with the community risk level set at high. (Ben Hohenstatt / Juneau Empire)
COVID-19 cases tick up over holiday weekend

Two CBJ employees among those testing positive

President Joe Biden signs his first executive order in the Oval Office of the White House on Wednesday, Jan. 20, 2021, in Washington. (AP Photo / Evan Vucci)
President signals plans to halt oil activity in Arctic refuge

The plans were announced on a fact sheet by the new administration on Biden’s inauguration day.

The author's fiancee Abby navigates their boat in the fading afternoon light. Shortly after returning to the dock, an otter took up residence aboard. (Jeff Lund / For the Juneau Empire)
I Went To the Woods: Dealing with an otter squatter

I assume it’s an otter because of shell fragments in the runny excretions left in the forward stowage

Members of the Recall Dunleavy group are close to achieving their goal for signatures, with only about 20,000 signatures remaining as of Jan. 19, 2021. (Ben Hohenstatt / Juneau Empire file)
Recall Dunleavy group gathers steam for final push

The group has nearly reached its signature requirement.

Has it always been a police car. (Michael Penn / Juneau Empire)
Police calls for Wednesday, Jan. 20, 2021

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

White House, tribes joined to deliver Alaska Native vaccines

The initiative has treated Indigenous tribes as sovereign governments and set aside special vaccine shipments.

Has it always been a police car? (Michael Penn / Juneau Empire)
Police calls for Tuesday, Jan. 19, 2021

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

Most Read