Living creature information
*This event has ended.* We exhibited baby Japanese giant spider crab crabs, the world's largest crabs.
April 21, 2026
We have begun exhibiting five baby Japanese giant spider crab crabs (megalopa larvae) that were born at Kaiyukan on Tuesday, March 3rd.
[Megalopa larva of the Japanese giant spider crab(approximately 3 mm)]
On Tuesday, March 3, 2026, aquarium keeper discovered that baby Japanese giant spider crab had been born in the tank . Approximately 500 of them were moved to a reserve tank, where they were fed with Artemia and sakura shrimp while their growth was monitored.
Immediately after birth, baby crabs are called "zoea larvae" and look very different from adults. Through repeated molting, they grow into "megalopa larvae" and then into "juvenile crabs" that resemble adults.
The baby crabs on display are megalopa larvae, which are extremely small, measuring only about 1 mm in body size and approximately 3 mm even with their legs extended. They are expected to grow into juvenile crabs (approximately 1 cm with legs extended) in the near future.
* (April 18, 2026) The megalopa larva has grown into a juvenile crab. → Blog post: "Japanese giant spider crab larva finally grows into a juvenile crab!"
At the Kaiyukan, we have successfully raised crabs to the "juvenile" stage twice in the past, in 2023 and 2025, and in 2025 we exhibited them for visitors to see.
This time, we hope you will take a look at the precious sight of the Japanese giant spider crab crab, the world's largest crab, which can only be seen at this time of year, and feel the mystery of life as you observe the differences in size and appearance between the young and adult forms.
Additionally, the growth of the Japanese giant spider crab crab larvae is also featured on the blog "Behind the Scenes at Kaiyukan" .
| Period | 2026/04/21～ 2026/06/11 |
|---|---|
| place | Kaiyukan aquarium keeper counter on the 4th floor of the Kaiyukan Entrance Building |
| kinds | Five megalopa larvae (approximately 3 mm) of the Japanese giant spider crab. |
*Exhibition may be canceled at short notice depending on the condition of the animals.
Japanese giant spider crab
English name: Japanese giant spider crab
Scientific name: Macrocheira kaempferi
The male is the world's largest crab, with its claws spread to over 3m .
It is also the world's largest species among arthropods, a larger taxonomic group, and is mainly found in the waters off the coast of Japan, but has also been caught in Taiwan and other places.
They usually live in deep waters and are known to migrate to shallow waters in the spring to spawn.
Check out this creature's blog too!
Latest News
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2026.06.12
news
[Important] Beware of fake ticket websites and scams.
Thank you for always using our facility. We have confirmed the existence of a fake ticket sales website (kaiyukan.world) that is falsely claiming to be an official ticket vendor for our facility, and victims are mainly coming from overseas. Official tickets for our facility are not sold through any channels other than the following official channels: Official/Authorized Sales Channels, Kaiyukan Official Website, Klook, KKday, Trip.com [Caution] You will not be admitted with an unauthorized ticket purchased from any site other than those listed above (such as SNS or resale sites). We also cannot be held responsible for any problems that may arise. If you come across any suspicious sites or tickets being sold at extremely low prices, please refrain from purchasing them. We ask for your understanding and caution so that everyone can enjoy our facility safely and securely.
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2026.10.07
Living creature information
From November 8th, we will be adding creatures collected by aquarium keeper in the Arctic Region to our exhibit!
From Sunday, November 8, 2026, the "Arctic Region" Aquarium (3rd floor underwater section) will be adding 17 species and 85 specimens of creatures that live in the Arctic Region Circle, including fish, crabs, and starfish, collected by aquarium keeper in the Arctic Region. Eyeshade's Sculpin (Scorpionfish) *First exhibit at Kaiyukan Arctic Cod (Polar Cod) Kaiyukan aquarium keeper Hokkaido University's training vessel "Oshoro Maru" on an Arctic voyage survey conducted over 43 days from June 19 to July 31, 2026, and collected approximately 27 species and 370 specimens of creatures. From these, 17 species and 85 specimens (planned), including three species being exhibited for the first time at Kaiyukan, such as the "Eyshade's Sculpin (Scorpionfish)," will be added to the exhibit, bringing the total number of Arctic creatures that live in the Arctic Region to 22 species and 205 specimens (planned). In addition, to coincide with the addition of these exhibits, we will be holding a special program called "A Special Experience from a aquarium keeper 's Perspective - Arctic Creatures Edition," where you can experience the process of moving the creatures from the back tank to the exhibit tanks—a task not usually seen by the public—alongside the aquarium keeper . You will hear lectures and anecdotes from the aquarium keeper who participated in the survey, as well as get to experience the process of moving creatures collected on site to the exhibit tank. *Please check the event page for details on how to participate. Main exhibited creatures Fish Doctor (Naked Greninja) Kelp Snailfish (Snailfish sp.) Fuzzy Hermit Crab (Hermit Crab) Blue King Crab (Oil Crab) Spiny Starfish (Starfish) Sea Raspberry (Coral) *The exhibit period and number of exhibited creatures may be changed without notice depending on the condition of the creatures.
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2026.10.06
Living creature information
A King penguin chick has been born.
~You can see the heartwarming scene of the parenting~ A baby King penguin was born in the "Antarctica" tank on Saturday, September 19, 2026. Since birth, the parents have been raising the baby under their belly, so it has been difficult to see, but about two weeks have passed since birth, and the baby is now occasionally peeking out from under the parents' feet. We are pleased to announce that there are now more opportunities to see the parenting, such as the parents feeding the baby mouth-to-mouth. The baby is growing well, and the aquarium keeper are monitoring its growth by weighing it every morning. King penguin chick born on September 19th (photographed on October 6th) [About the King penguin Chicks] ・Egg-laying date: Wednesday, July 22, 2026 ・Hatching date: Saturday, September 19, 2026 ・Sex: Unknown ・Weight: Approximately 200g (immediately after hatching) → Approximately 840g (as of October 6th) [Second chick] ・Hatching date: Wednesday, September 24, 2025 ・Sex: Unknown ・Weight: 192g (immediately after hatching) → Approximately 350g (as of October 7th) --> *Depending on the condition of the chicks, the exhibit may be canceled without notice.