Kurage Wonder Research Club Member's Observation Log / Iori Jellyfish Edition

Introducing the animals
Kyoto Jellyfish Research Department

Kurage Wonder was established in 2020. Here you can encounter around 30 different types of jellyfish.
Jellyfish have a wide variety of characteristics. By learning about the highlights of each species, you may be able to find your favorite jellyfish.

Iori jellyfish, born in the Hokuriku region

The Iori jellyfish is characterized by its bell-shaped, transparent umbrella and the striking red gonads inside. While the name "Iori" might bring to mind buildings or people's names, the name actually originates from a place name.

The Iori jellyfish, though small, has a strong presence.

It was named after its discovery in a fixed net in Iori-cho, Nanao City, Ishikawa Prefecture. Kyoto Aquarium has been breeding and raising this jellyfish since 2019, a year before the opening of the Kurage Wonder.

Grow big!

Currently, we keep the Iori jellyfish in small, circular tanks, but in the past, we raised them in a small refrigerator, making it difficult for customers to see them. Why were the Iori jellyfish kept in a refrigerator?

This was because the Iori jellyfish were small. It was the first time Kyoto Aquarium had attempted to breed Iori jellyfish. Initially, it was difficult to raise them to a large size; they should have grown to about 3 centimeters, but their growth stopped at less than 1 centimeter. The circular tanks in the Kyoto Jellyfish Research Department where other jellyfish are kept were a little too large for the Iori jellyfish, and to prevent them from having trouble catching food or becoming ill due to strong water currents, they were placed in petri dishes with no water flow and raised in a refrigerator where the water temperature could be kept low.

This is a two-week-old Iori jellyfish. It's being kept in a small petri dish.

At first, raising jellyfish from newborn babies to adults was difficult. I constantly wondered, "Is the water temperature too high or too low for the Iori jellyfish?" and "Is the type of food I'm feeding them unsuitable?" I spent each day carefully observing how to care for them, and gradually, they started to live longer.
I was trying out various kinds of food to find the perfect food for the Iori jellyfish, including finely chopped white shrimp that I give to my glass jellyfish, and minced mysid shrimp that I give to my Pacific sea nettle and purple striped jellyfish babies.

A long-awaited move

"Maybe it'll get bigger?" Signs of change appeared in the Iori jellyfish. Thanks to the trial and error of the animal care staff it, it seems that the Iori jellyfish has grown a bit bigger than usual. "This will work!" The jellyfish team all looked at the Iori jellyfish with the same feeling. Finally, the day came for it to leave the refrigerator and move into the same circular tank as the other jellyfish.

The jellyfish Iori moved to a large tank for the first time.

The design creates a water flow to prevent air from entering the umbrella, which is shaped like an inverted cup.

Watching the Iori jellyfish drifting freely in the large tank brings a smile to your face. Observing the jellyfish and interacting with them daily is an important role for the animal care staff at the Kyoto Jellyfish Research Department.

Strawberries? Or pickled plums?

Now, when you saw the Iori jellyfish, didn't you think it resembled something? Opinions among the animal care staff are divided on this. Some say it resembles a strawberry daifuku, while others say it resembles a pickled plum onigiri. Both strawberry daifuku and pickled plum onigiri are wrapped in white and have a red, round symbol in the middle. I can understand both opinions.

Strawberry mochi, or perhaps a pickled plum rice ball?

"Am I the only one at the animal care staff who thinks this way?" you might think, but it turns out that the Iori jellyfish is sometimes called "pickled plum" by local fishermen. The boneless bell of the jellyfish is gelatinous and very fragile, and can only maintain its shape in water. Therefore, when an Iori jellyfish gets caught in a net and is pulled out of the water, its bell shrinks to a small size, leaving only the red gonads in the center, which is why it is likened to a pickled plum.

Which do you think the Iori jellyfish looks like? By the way, I prefer the strawberry daifuku! Please go see an Iori jellyfish in person and let me know what you think.

[Exhibition and Animal Care Team, Mutsuura]

Check out the Kyoto Jellyfish Research Club for other jellyfish columns!