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.

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.

2026.09.05

Living creature information

[Limited Time Only] We are exhibiting baby Porcupinefish.

Baby Porcupinefish are on display for a limited time at the aquarium keeper counter on the 4th floor of the entrance building. These babies were born from eggs laid by Porcupinefish in the "Cook Strait" tank and have been carefully raised by the aquarium keeper in the back area. Highlights of the babies include their dark body color, which differs from that of adults, and tiny spines that can be seen upon closer inspection. Be sure to take a close look at their adorable appearance as they swim, diligently moving their tiny fins. Period: September 5, 2026 - End date TBD Location: aquarium keeper counter, 4th floor of the Kaiyukan entrance building Number of exhibited individuals: 1 (approximately 3cm in length) *The exhibit may be suddenly canceled depending on the condition of the animals. Also, aquarium keeper will be at the aquarium keeper counter during the following times. We will introduce current topics such as the animals on display and baby animals being raised in the back area. tr th, tr td { border: 1px solid #e6e6e6; } tr th { background-color: #f5f5f5; } Commentary by aquarium keeper Weekdays 13:10-14:00, 15:30-16:20 Weekends and holidays 11:00-11:50, 13:10-14:00, 15:30-16:20 Porcupinefish Scientific name: Allomycterus pilatus The English name "Porcupine" refers to a porcupine, and its entire body is covered in spines. The spines are always erect and cannot be moved. It inhabits the waters from New Zealand to South Australia, where cold ocean currents from Antarctica flow in.

2026.08.24

Living creature information

*Exhibition has ended. A large jellyfish with a diameter of 60cm has appeared! We have started exhibiting the large "Ariake Bizen Kurage (Japanese Name)".

*The exhibition of the large jellyfish "Ariake Bizen Kurage (Japanese Name)," which inhabits the Ariake Sea, has ended. We will be exhibiting it for a limited time of approximately one month. The Ariake Bizen Kurage (Japanese Name) is a large jellyfish that grows to a diameter of 60 cm and a weight of about 20 kg. In the vicinity of the Ariake Sea in Kyushu, it is caught for food in the summer. Kaiyukan has been conducting research on the Ariake Bizen Kurage (Japanese Name) in the Ariake Sea since 2001, and in 2002, it succeeded for the first time in transporting and exhibiting a large individual. This year, coinciding with the start of the "jellyfish fishing" season in the Ariake Sea, we have collected Bizen jellyfish for research and exhibition. Through this exhibition, Kaiyukan hopes to provide an opportunity for people to become interested in living creatures and the natural environment. Exhibition Period: August 22, 2026 onwards (approximately 1 month) Exhibition Location: 3F, Aquarium "Jellyfish" Exhibits: 2 individuals with a bell diameter of approximately 60cm, 1 individual with a bell diameter of approximately 30cm, total of 3 individuals *The exhibition period and number of exhibits may be changed without notice depending on the condition of the creatures. About Ariake Bizen Kurage (Japanese Name) Scientific name: Rhopilema esculentum In Japan, it is distributed only in the Ariake Sea. It is a large jellyfish that grows up to a bell diameter of 60cm and weighs about 20kg, and is called "Edible jellyfish" in English because it is edible. It is caught by gillnet fishing off the coast of the Ariake Sea from around July to October. In recent years, in order to avoid confusion with similar species, the name has been changed from a type of Bizen jellyfish to "Ariake Bizen Kurage (Japanese Name)".

2026.08.03

Living creature information

We have begun exhibiting "Clione" (sea angels) collected by aquarium keeper in the Arctic Region.

From August 2nd, 2026 (Sunday), we have begun exhibiting approximately 140 sea angels (Clione), each about 2 cm in size, collected in the Arctic Region Circle, in the "Arctic Region" section of the Aquarium . These sea angels were collected by Kaiyukan's aquarium keeper who accompanied Hokkaido University's training vessel, the "Oshoro Maru," on an Arctic expedition from June 19th to July 31st, 2026. Sea angels are a type of mollusk that does not have a shell and inhabit the Arctic Region and surrounding waters. They live by flapping their wing-like "pteropods" and drifting through the ocean. In addition to sea angels, this expedition also collected valuable fish and invertebrates that inhabit the Arctic Region, and we will announce when these will be exhibited. Details of the Arctic Region expedition and the collection of organisms can be found on the blog "Kaiyukan's Behind the Scenes." [About Clione] Clione are shellless mollusks, also known in Japan as "Clione" (naked sea slug). In Japan, they are commonly called "Clione," derived from their genus name. They inhabit cold waters such as the Arctic Region and its surrounding areas, drifting through the sea by flapping their wing-like organs called "pteropods." They primarily feed on the sea snail *Lysimachia japonica*, another type of mollusk, catching them by extending six tentacles (buccal cones) from the mouth on the top of their heads. *Please note that the exhibition period and number of exhibits may change without notice depending on the condition of the organisms.

2026.07.01

Living creature information

A second California sea lion pup of the year has been born.

~Two calves born in the same year for the first time in four years~ A male California sea lion lion pup was born in the Monterey Bay tank at 7:28 a.m. on Wednesday, July 1, 2026. Another California sea lion pup was born on Wednesday, June 17, making this the second birth this year. On Monday, June 29, 2026, signs of labor were observed in Asuka (16 years old), a female living in the Monterey Bay tank, and aquarium keeper intensified their observations. At 7:28 a.m. on Wednesday, July 1, the birth of the male pup was confirmed. Nursing was observed about two hours after birth, and the postpartum recovery appears to be progressing smoothly. California sea lion pups are nourished by their mother's milk for about one year after birth. As the parenting takes place in the exhibit tank, depending on the time and location, you may be able to see the heartwarming scene of mother and child. The mother and baby (photographed on July 1) About the newborn baby (photographed on July 1) ・Date of birth: Wednesday, July 1, 2026 ・Exhibition tank : Monterey Bay tank on the 7th floor of Kaiyukan Aquarium ・Body length: 60 cm (estimated) ・Sex: Male ・Parents: Mother Asuka (16 years old), father unknown About California sea lion English name: California sea lion Scientific name: Zalophus californianus They inhabit only the eastern coast of the North Pacific Ocean. When fully grown, males reach a body length of approximately 200 cm and a weight of approximately 300 kg, while females reach a body length of approximately 170 cm and a weight of approximately 100 kg. Males are entirely dark brown, while females are a slightly lighter dark brown. Their limbs are well-developed and are useful not only for swimming in the water but also for walking on land. They are polygamous, with one male leading a group called a "harem" with approximately 30 females and offspring. The gestation period is approximately one year. Typically, they give birth to one calf at a time and continue nursing it for about a year after birth. ★At the Kaiyukan, California sea lion and Southern rockhopper penguin have been born one after another from May to June 2026, experiencing a baby boom. → A California sea lion pup was born (June 18, 2026) →Baby boom!! A Southern rockhopper penguin chick was born (June 8, 2026)

2026.06.18

Living creature information

California sea lion baby born

Mother is raising her baby in the Monterey Bay tank A California sea lion pup was born in the Monterey Bay tank on Wednesday, June 17, 2026. This is the 20th California sea lion birth at Kaiyukan Kaiyukan . On Wednesday, June 10, 2026, signs of labor were observed in "Nami (14 years old)," a female living in the Monterey Bay tank, and aquarium keeper intensified their observations. At 9:47 PM on Wednesday, June 17, the birth of the baby was confirmed. The baby's sex has not yet been confirmed. *Later, it was determined to be a male. Nursing was observed about two hours after birth, and the postpartum recovery seems to be going smoothly. California sea lion pups are nourished by their mother's milk for about one year after birth. As the mother is raising her baby in the exhibit tank, depending on the time and location, you may be able to see the heartwarming scene of mother and child. Parent and child (photographed on June 18) Baby (photographed on July 1) About the baby born this time (as of June 18, 2026) (photographed on June 18) ・Date of birth: Wednesday, June 17, 2026 ・Exhibition tank : Monterey Bay tank on the 7th floor of Kaiyukan tank・Length: 60 cm (estimated) ・Weight: Unknown ・Sex: Male ・Parents: Mother Nami (14 years old), Father Unknown About California sea lion English name: California sea lion Scientific name: Zalophus californianus They inhabit only the eastern coast of the North Pacific Ocean. When fully grown, males reach a length of approximately 200 cm and a weight of approximately 300 kg, while females reach a length of approximately 170 cm and a weight of approximately 100 kg. Males are entirely dark brown, while females are a slightly lighter dark brown. Their limbs are well-developed and are useful not only for swimming in the water but also for walking on land. They are polygamous, with one male leading a group of about 30 females and offspring, known as a "harem." The gestation period is about one year. Typically, they give birth to one offspring at a time and continue nursing it for about a year after birth.

2026.06.08

Living creature information

Baby boom!! Southern rockhopper penguin chicks have been born.

You can observe the chicks raising their young in the exhibit tank . On May 29th (Fri), June 3rd (Wed), and June 7th (Sun), 2026, one Southern rockhopper penguin chick was born in the "Falkland Islands(Malvinas)" tank , bringing the total to three chicks that are growing up healthy. The chick born on May 29th already weighs over 1 kg and is growing bigger every day. aquarium keeper are monitoring the chicks' health by weighing them and observing them every morning. *The exhibit may be closed without notice depending on the condition of the chicks. In addition, to commemorate the birth of the Southern rockhopper penguin chicks, there will be poster displays and explanatory events about the ecology and breeding of Southern rockhopper penguin. →Click here for details Southern rockhopper penguin family (photographed on June 15) [About the Southern rockhopper penguin chicks] [1st chick]・Hatching date: May 29, 2026 (Friday)・Sex: Unknown・Length: Approximately 20 cm・Weight: 80.0 g (immediately after hatching) → Approximately 530 g (as of June 8) → 1045.5 g (as of June 15) [2nd chick]・Hatching date: June 3, 2026 (Wednesday)・Sex: Unknown・Length: Approximately 15 cm・Weight: 45.5 g (immediately after hatching) → 352.0 g (as of June 15) [3rd chick]・Hatching date: June 7, 2026 (Sunday)・Sex: Unknown・Length: Approximately 15 cm in length, weight: 86.6 g (immediately after hatching) → 368.0 g (as of June 15th). Photo taken on June 29th. They are growing rapidly! Baby 1 (left), Baby 2 (left), Baby 3 (left)

2026.04.27

news

The exhibit of the Tufted puffin will end on May 10, 2026.

Due to the renovation of the "Aleutian Islands" tank, the exhibit of the Tufted puffin will end on Sunday, May 10, 2026. Kaiyukan collaborated with Aqua World Ibaraki Oarai Aquarium to promote joint research on the ecology and breeding of Tufted puffin, and began exhibiting them on June 29, 2018, after receiving a transfer of Tufted puffin from the aquarium. Since then, a total of three puffins have been successfully bred, and one of them has even been successfully raised artificially, so we believe that we have achieved a certain degree of success in achieving our initial objectives. The Tufted puffin will be kept in the back area for health management before being moved to Aqua World Ibaraki Oarai Aquarium. Further details regarding the renovation of the "Aleutian Islands" tank will be announced as soon as they are decided.

2026.04.21

Living creature information

*This event has ended.* We exhibited baby Japanese giant spider crab crabs, the world's largest crabs.

On Tuesday, March 3rd, we began exhibiting baby Japanese giant spider crab crabs (megalopa larvae, 5 individuals) that were born at the Kaiyukan . [ Japanese giant spider crab crab megalopa larvae (approx. 3 mm)] On Tuesday, March 3rd, 2026, aquarium keeper discovered baby Japanese giant spider crab crabs 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, the babies 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 babies on display are "megalopa larvae," and are very small, with a body size of only about 1 mm and a leg span of about 3 mm. They are expected to grow into juvenile crabs (approx. 1 cm with legs spanned) in the near future. * (April 18, 2026) The megalopa larvae have grown into juvenile crabs. → Blog: "Japanese giant spider crab larvae finally grow into juvenile crabs!"Kaiyukan has successfully raised Japanese spider crabs to the juvenile stage twice in the past, in 2023 and 2025, and in 2025 they were exhibited for visitors to see. This time, we would like you to come and see the precious sight of the world's largest crab, the Japanese giant spider crab crab, which can only be seen at this stage, and feel the mystery of life from the difference in size and shape between the larvae and adults. The growth of the Japanese Kaiyukan crab larvae is also introduced in the blog "Behind the Scenes at Japanese giant spider crab ". Period: April 21, 2026 - June 11, 2026 Location : Kaiyukan Entrance Building 4F aquarium keeper Counter Species: 5 Japanese giant spider crab crab megalopa larvae (approx. 3mm) *The exhibit may be suddenly canceled depending on the condition of the creatures. The Japanese giant spider crab ( Japanese giant spider crab kaempferi) is the world's largest crab, with males reaching over 3 meters in length when extending their claws. It is also the world's largest species of arthropod, a larger taxonomic group, and is mainly distributed in the waters around Japan, but has also been caught in Taiwan and other areas. It normally lives in deep-sea areas and is known to migrate to shallow waters in the spring to lay eggs.