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16 July 2014 Share This Share this article

MBARI helps Monterey Bay Aquarium figure out the life-cycles of glowing jellies

An adult flower-hat jelly in a tank at the Monterey Bay Aquarium. Photo by Randy Wilder © Monterey Bay Aquarium.
Thousands of visitors to the Monterey Bay Aquarium have marveled at the beautiful, glowing tentacles of flower-hat jellies (Olindias formosus). However, in addition to the beautiful "medusa" form that visitors see at the aquarium, these animals go through several other life stages, which look very different from the jellies on display. After 12 years of working with these jellies, researchers at the aquarium and MBARI recently described two of the other life stages of this jelly. This research has finally allowed the aquarium to grow these beautiful animals in house, and may also help researchers predict blooms of these jellies, which can deliver a nasty sting to humans.

A paper describing the team’s achievement was published online in the Journal of the Marine Biological Association of the United Kingdom in June 2014. The paper was written by aquarists Wyatt Patry, Thomas Knowles, and Michael Howard of the aquarium, and Research Technician Lynne Christianson of MBARI.

According to Patry, “Our team succeeded through collaboration, diligence, and a bit of good luck.”

Life cycle of the flower-hat jelly (not to scale; appearance of eggs and planula is hypothetical). Photos © Monterey Bay Aquarium.
The aquarium’s research on flower-hat jellies began in 2002, during the Jellies: Living Art special exhibition. While working on that exhibit, aquarists learned to culture the jelly's fertilized eggs and larvae. Despite this breakthrough, the aquarists were never able to get the larvae to turn into polyps, the next stage in the jelly's life cycle. Under the right conditions, such polyps form buds that are released into the water as baby jellies (see diagram).

Almost 10 years later, the aquarium opened a new special exhibition called The Jellies Experience. For this exhibit, Patry and his team tried again to culture the jelly through its full life cycle. About six months after putting a batch of flower-hat jellies on exhibit, Patry noticed tiny polyps growing on mesh within one of the jelly tanks. He also found tiny medusae in the water. Like the adult jellies, these life stages of the jelly glow (fluoresce) when exposed to blue light.

A young flower-hat jelly, about one millimeter wide, glows under blue light. This photograph was taken using a yellow filter that makes the fluorescent parts of the jelly stand out. Photo by Thomas Knowles © Monterey Bay Aquarium.
“I was only able to see [the polyps] because they are fluorescent, like the adults,” Patry said. “From there we worked with the polyps to refine the ideal food and temperature requirements for them to produce more babies.”

But before publishing their results, the aquarists needed to confirm that the polyps and juveniles were the correct species. Because the early life stages of many jellies look similar, the researchers could not be certain which species they had. So they sent samples to Christianson, who analyzed DNA from the polyps, juveniles, and adults to confirm that they all were all, indeed, one species.

Flower-hat jellies live a dual lifestyle, attaching to the seafloor during the daytime, but swimming through the water at night in search of prey. Although their beautiful colors make them very popular aquarium animals, flower-hat jellies also pack a powerful sting, which they use to capture fish.

During large "blooms" of flower-hat jellies in Japan and Brazil, hundreds of beachgoers have been stung, and at least one person has died. By shining new light on how these jellies grow and reproduce, the recent research could help marine biologists predict where and when such blooms are likely to occur.

For more information on this article, please contact Kim Fulton-Bennett:
(831) 775-1835,

Original journal article:
Patry, W., Knowles, T., Christianson, L., and Howard, M. (2014) The hydroid and early medusa stage of Olindas formosus (Cnidaria, Hydrozoa, Limnomedusae). Journal of the Marine Biological Association of the United Kingdom Published online: 24 June 2014 DOI

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