The monthly invasion of box jellyfish at Waikiki claimed 164 sting victims yesterday, including a 15-year-old girl who was taken by ambulance to Straub Clinic & Hospital after suffering a serious reaction to the sea creature's toxin.

The girl, whose name was not released, was stung "pretty severely" about 7:25 a.m. on the beach behind the Outrigger Canoe Club at the diamondhead end of Waikiki, said Bryan Cheplic of the city's Emergency Services Department. The girl experienced pronounced swelling from the sting but did not have a life-threatening allergic reaction, he said. She was last reported in stable condition.

Ocean safety officials reported that 296 jellyfish had been collected from the beach along Waikiki as of 3 p.m. yesterday. Two people reported being stung at Hanauma Bay and one at the Makai Pier, although no jellyfish were reported found on windward beaches. There were no reports of box jellyfish on O'ahu's north and west shores.

Rob Miller of the city's Ocean Safety and Lifeguard Services Division said today's jellyfish threat is likely to lessen, although swimmers and beachgoers should remain on alert. He called yesterday's box jellyfish invasion an "average" event.

Box jellyfish wash ashore at night during their spawning cycle eight to 10 days after each full moon. They are usually present for a day or two before disappearing until the next cycle. This pattern has allowed marine scientists and ocean safety officials to devise a calendar predicting when the jellyfish are likely to return. On those days, signs are posted on beaches warning swimmers to stay out of the water.

"We try to warn them about it. Some people listen and some don't," Miller said.

The jellyfish are hard to spot in the water and swimmers can get stung from tentacle particles that have broken off from the jellies. Miller said he speaks from experience when he advises beachgoers that the creatures can sting even if they are dead on the sand.

"I get stung pretty much every cycle just from picking them up or rubbing my face with my gloves," he said.

For reasons unknown, the jellyfish mostly swarm on O'ahu's south shore, although they are periodically reported on the Neighbor Islands. What they are doing the rest of the month is also a mystery, although it is believed they descend to deep water in the daylight.

Carybdea alata, the largest of the three box jellyfish species known in Hawai'i, is identified in the recurring swarms that have been reported on O'ahu since late 1988. It can reach up to 2 inches in diameter and 3 inches in length.

The jellies have four pink tentacles armed with microscopic stinging cells that trail from their transparent bodies. Each cell fires a barbed thread that can penetrate the skin and deliver toxin that causes a burning sensation, according to the Waikiki Aquarium.

The stings can cause intense pain and result in complications such as swelling and difficulty breathing, but there have been no deaths from box jellyfish in Hawai'i, according marine biologist Susan Scott, who co-authored the book "All Stings Considered: First Aid and Medical Treatment of Hawai'i's Marine Injuries."

"It's painful but the likelihood of it being fatal is very, very low," she said.

Once you're stung, there is no way to counter the effects of the jellyfish toxin, she said, and any treatment is aimed at relieving pain.

Vinegar can neutralize the undischarged cells that remain on the skin and keep the sting from getting worse, but other attempted remedies such as human urine and meat tenderizer can actually have the reverse effect, Scott said.

She said the rule in treating jellyfish stings is: "Don't make it worse. Don't try putting on all kinds of things that might make it worse. You don't know what is going to make it worse. A sting is a sting and it's not going to go away."

Scott participated in two studies that found little difference between use of hot or cold packs to ease the pain from jellyfish stings. Dousing stings in fresh water or using a product called Sting-Aid also didn't seem to have an impact one way or the other.

She said over-the-counter hydrocortisone creams and oral doses of Benadryl may help relieve some of the pain, which can linger for hours.

Emergency care should be sought if a stinging victim experiences breathing difficulty or feels weak, Scott said.

For a box jellyfish arrival calendar, visit www.honolulu.gov/esd/oceansafety/boxjellymainpage.htm.

For information regarding ocean conditions, advisories and warnings, call the city's Ocean Safety Division at 922-3888 or go to http://oceansafety.soest.hawaii.edu.

Reach Christie Wilson at cwilson@honoluluadvertiser.com.