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

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.

Is it too small? The home of the jellyfish

The Kyoto Jellyfish Research Club exhibits a small glass bottle containing a jellyfish called *Euphyllia glabrescens*, which drifts along in a chain of air bubbles. Its name comes from the fact that its gonads, which extend from the center of its bell, are arranged in a chain-like fashion.

While other jellyfish gradually move to larger tanks as they grow, the bead jellyfish spend their entire lives in this bottle. This is because even as adults, bead jellyfish are very small, with their bells less than 1 cm in size. Therefore, a large tank would be too spacious for them to thrive. In other words, a glass bottle is the perfect home for these tiny bead jellyfish.

[Tiny Jellyfish Feeding Time]

The surprising origin of the jellyfish at Kyoto Aquarium

In simple terms, jellyfish breeding involves taking fertilized eggs from parent jellyfish, placing them in a location where they develop into polyps, which resemble sea anemones, and then managing those polyps. Sometimes, jellyfish populations are increased by exchanging polyps with other aquariums. In 2020, when we were looking to increase the variety of jellyfish during the renovation of the jellyfish area, one of the aquarium's animal care staff said, "There are some polyps of the jellyfish *Rhinoceros jellyfish* on the artificial rock (the part that looks like a rock) in the large tank, so I'll go and collect them," and he went and collected them for us in between cleaning.

They have carefully nurtured that polyp to this day, and have been continuously obtaining baby jellyfish from it. It was an amazing feat, demonstrating the keen observation skills of the animal care staff.

How far can that rosary stretch?

The jellyfish's symbol is its chain-like gonads, but when it's first born, it only has one.

The number of gonads increases as the jellyfish grows, and it is said that they can increase to up to nine, excluding the bottom stomach. Counting the animal care staff the jellyfish. One day, the jellyfish's gonads seemed longer than usual. Curious, we counted them and found that it had a whopping 12 gonads!

Whether it's a mutation or the jellyfish at Kyoto Aquarium are a different species from the common jellyfish, we don't know the reason, but we were happy to find such an unusual jellyfish. There may be some individuals with long beads among the jellyfish currently on display, so please try to find them!

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