Okinawa Churaumi Aquarium

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Ultrasonogram solved the mystery of breathing system of the manta ray embryo

2012,6,14 category:Report

 Like humans, manta ray embryos develop to a large size in the mother’s body. But it has been a mystery of how the manta ray embryo acquires oxygen from the mother without a placenta and an umbilical cord.

 In 2008, Okinawa Churaumi Aquarium conducted an ultrasonographic experiment on a pregnant manta ray for the first time. The researchers at the Research Center(OERC) of the Ocean Exposition Commemorative Park Management Foundation and Hokkaido University obtained footage of the respiratory system of the manta ray embryo using the sonograms.
 This work was published online in Biology Letters (The Royal Society) in 2012.6.6.
Title: Live-bearing manta ray: how the embryo acquires oxygen without placenta and umbilical cord.

 This work was featured in ScienceNOW (Science-AAAS) “A Peek Inside the Manta Ray Womb” (by Helen Fields).

You can see the ultrasonogram of the manta ray embryo here. Ultrasonogram of the manta ray embryo

Staffs at Okinawa Churaumi Aquarium investigated the pregnant manta ray using a sonogram.

Contact us : Okinawa Churaumi Aquarium
424 Ishikawa, Motobu-cho, Kunigami-gun, Okinawa Japan 905-0206

Experimental study on artificial flukes for a Bottlenose dolphin “Fuji”

2012,4,1 category:Report


In Fall 2002, a female bottlenose dolphin (Tursiops truncatus) “Fuji” lost 75% part of her flukes because of an unknown disease. Would it be possible to make the world’s first artificial flukes? Would the flukes allow her to swim and jump again as before? For scientific research, we started this experimental study on artificial flukes in cooperation with Bridgestone Co. Japan’s largest tire maker.

About “Fuji”

Fuji was caught in Kawana, Itoh, Shizuoka prefecture and transported by air to Ocean Expo Park, Okinawa in November 1976.
Her estimated age is 42, approximately 271 cm in length and weighs 211 kg as of 2011. She is a great mother of three children. Curently, her children Conny (female, born in June 9, 1989), and Chao (male, born in November 18, 1995) is living in the park with her.

The unknown disease on her flukes

Fuji has suffered from the unknown disease since October 16, 2002. She had symptoms such as loss of appetite, discoloration and necrosis in distal parts of flukes. The blood analysis and biochemical examination revealed she had a complex of infection and circular insufficiency. We excised the diseased parts by electronic surgical knife on October 25 and on November 7. With antibiotics and transfusion for 60 days, she thoroughly recovered from the disease, although she lost 75% of her flukes.

The first step of the project

This project first started when our veterinarian consulted for assistance to Bridgestone Sports Co.,Ltd. on November 27, 2002. One week after this contact, Bridgestone Co. agreed to cooperate in the project. To compensate her lost flukes, we officially started to develop artificial flukes in May 2003.

The goal of this project was to give scientific answers for the following questions:

We started this project not from the compassion for Fuji only, but for a scientific experiment. Fuji did not have any problem living in the park. It was reported that wild cetaceans without flukes appeared.

How to make artificial flukes

The first flukes cast was made of silicon on July 5, 2003. We developed the first model (40° hardness silicone rubber, 48cm wide, 30cm long, 2000g, Photo①) on September 12. But when tested on Fuji, it did not work well because of the attachment problems. The design of attaching belts caused scratches on her flukes. After reconsideration, we decided that we needed a more accurate mold of Fuji’s flukes and ordered to a famous acrylic sculptor. (Photo②)
At the beginning of March 2004, the band type second model (70° and 40° hardness silicone rubber, 70cm wide, 25cm long, 2200g, Photo③) was made. Since the band type receives greater water resistance, it was necessary to be improved into the cowling type. In mid-June of 2004, the cowling type (70° hardness silicone rubber, containing carbon cross reinforced plastics, 70cm wide, 25cm long, 2200g) was tested on Fuji. Observing the movement of the flukes same as other dolphins in the park, this model was confirmed to be functionally useful.
At this stage, artificial flukes were mechanically strong enough for swimming but not enough to sustain physical momentum of jumping. After the attempt to improve the material for the reinforced plastics and silicon rubber strength, we developed the flukes with stronger natural rubber material. In mid-Dec of 2004, the cowling type olympic model (70° hardness silicone rubber, containing cfrp, 70cm wide, 25cm long, 2500g, Photo④) was made in cooperation with Bridgestone Cycle Co., Ltd. It makes Fuji to jump 3m at the highest point. Curently we use the cowling type YBECC model (natural rubber, containing fabric reinforced plastics for conveyor, 70cm wide, 35cm long, 2500g, Photo⑤), which enable to wear for a long time by adopting a durable natural rubber materials. This model allow mass production by hot pressing method with exclusive alminium mold and receive a permanent supply.

The Institute of Cetacean Research and our aquarium collaborated to analyze the swimming speed of the dolphin and demonstrate a significant benefit of such artificial flukes.

Training of Fuji

Rehabilitation training (1st stage)

In nature, the dolphins dislike to be attached a foreign object on their body. Fuji initially rejected artificial flukes. Therefore, we phased attachment training for Fuji.
For dolphins’ health control, it is very important to accustom them to the husbandry training. They need to allow the trainers to insert a thermometer into their anus and they need to lift their flukes out of water for taking blood samples. These trainings make it easy to check dolphins’ health conditions. The rehabilitation training of Fuji was similar to the husbandry training.
1) First, we taught Fuji to show her flukes at the trainer’s sign and let the trainer touch the flukes.
2) When she was accustomed to being touched, a piece of cloth or rubber band was attached to her flukes.
3) We continued this training patiently till Fuji get used to it. Finally, attaching artificial flukes was attempted.

Training was not easy as it might sound. At the beginning of training, Fuji had strong reaction to artificial flukes. She would struggle out of the trainer’s hand and swim away.
However, the trainers took time to train her patiently. We never forced the training to her aiming she became perfectly fine with the flukes.

Rehabilitation training (2nd stage)
When she became comfortable with artificial flukes, we started the next stage of the rehabilitation training. The first step of this stage was swimming training with the flukes. Even though she got a new flukes, she did not start swimming immediately. She was used to just floating in the pool and being hand-fed by the trainers. She got tired easily as we often saw her resting.
1) Trainers threw fish into the pool to let Fuji swim after the food.
2) Two trainers called Fuji using underwater bells at the both ends of the pool. She was trained to swim back and forth between them.
3) Next step was to make Fuji swim from 4m deep tank into 50cm shallow pool. In the shallow pool it was much easier for the trainers to attach the flukes to Fuji.
This last step took a long time. The shallow pool was an unfamiliar place for Fuji so she was scared. Though she could enter to the shallow pool, she felt uncomfortable and swam back to the main tank soon.

Trainers attracted Fuji to the shallow pool with the food. Now she can not only let trainers attach artificial flukes but also receive health check in the shallow pool.
4) When she got used to wearing the flukes, we began to train her to jump and touch a target. The training was started without attaching artificial flukes. When she learned to jump without the flukes, we started training with the flukes attached.
Fuji became able to jump strongly and touch the target. Now she can also do high jumps.

You can meet Fuji wearing artificial flukes about 4 hours a day at the Dolphin Lagoon Pool.

Future Plans

So far we have made 38 artificial flukes of 8 versions. However, the newest version is not yet perfect. We still continue our research for better materials and way of attachment. We are still trying out new ideas. At the same time, the research for artificial flukes might give us an insight into the function and mechanism of the natural dolphin flukes.
In order to achieve our goals, we would like to get more people involved and ask for diverse opinions.
Please come and visit Fuji at the Dolphin Lagoon Pool. We welcome your visit and will be happy to answer your questions.
Artificial flukes were registered as a patent in December 2009. (Patent No. 4421491)

Despite the effort of the treatments, Fuji died on November 1st (Sat) 2014, 2:45 p.m.
We would like to thank you for encouraging Fuji all time.

Dissection of the world class rare species ”Megamouth Shark”

2011,3,19 category:Report

We undertook dissection of this extremely rare species “Megamouth Shark” at our Aquarium shark research facility for three days, from March 1 to 3, 2011.

This Megamouth Shark was caught in the net of a Skipjack fishing boat east of Ibaragi Prefecture on July 9, 2007 and was landed at Ishimaki-port, Miyagi Prefecture.
It is a female with a body length 3.6 meters and weight of 360 kg.
This Megamouth Shark has now been carefully prepared with “plastination”, a new and intriguing way to preserve specimens, which will be yet another world first.
Experts in the preparation of plastination include Mr. Kazuhiro Nakatani, Professor Emeritus at Hokkaido University and Mr. Tanaka Akira, Professor Emeritus at Tokai University of Marine Science and Technology.

After determining the volume of water the Megamouth’s huge might hold by filling it with water balloons, next the backbone was separated to determine the age of the shark. Finally the plastinated specimen was prepared, and a CT Scan was made of the its head.
We hope to discover new things by analyzing this new and intriguing data.

We sincerely appreciate and thank everyone involved in this complicated preparation and research process.

Contact us

Okinawa Churaumi Aquarium
424 Ishikawa, Motobu-cho, Kunigami-gun,
Okinawa, Japan 905-0206

  • TEL:+81-980-48-2742
  • FAX:+81-980-48-4399

The Oriental Zodiac Tank 2011 ended on a High Note

2011,1,11 category:Report

Over the recent holidays from December 26, 2010 to January 3, 2011, we exhibited the Oriental Zodiac Tank (2011 is the Year of the Rabbit in the Oriental Zodiac) for learning about ‘Rabbit-fish’ and other marine creatures through enjoyable quizzes and panels with our staff.


A special columnar tank decorated for New Year


It was our pleasure that many people visited our Aquarium, enjoying taking pictures and interested in observing the marine creatures of the Zodiac 2011 tank. In this special tank there were ‘Rabbit-fish’ (which have mouths which looks like a Rabbit’s), and Wedge Sea Heres (which have tentacles which look like the ears of a Rabbit).

There were also various exhibitions, such as the kanji (Japanese characters) for rabbit, which were made of Egg cowrie shells (as pictured above) and attracted the attention of many visitors. And there were a lot of families taking the quizzes together, and children making enthusiastic notes about quiz answers 2011干支水槽3or panel explanations.
This exhibition was intended to help understanding and increase interest in marine life and the creatures while it was exhibited during December 26 to January 3, 2011.

We will continue to have this kind of event every year hoping you will become more and more intrigued with marine creatures.
Don’t miss ‘The Oriental Zodiac Tank 2012′ next year!

We hope you will learn something new every time you visit our Aquarium!

Contact us

Okinawa Churaumi Aquarium
424 Ishikawa, Motobu-cho, Kunigami-gun,
Okinawa, Japan 905-0206

  • TEL:+81-980-48-2742
  • FAX:+81-980-48-4399

The Author of “Lady with a Spear” and the world’s top shark scientist,Dr. Eugenie Clark, visited Okinawa Churaumi Aquarium

2010,11,9 category:Report

On November 2nd- 3rd, the American ichthyologist Dr. Eugenie Clark visited the Aquarium and commented “Okinawa Churaumi Aquarium is certainly the most beautiful aquarium in the world that I have ever seen or read about.” Here is a report of her visit:

Left: Dr. Clark writing her impressions of the Aquarium/ Right: Dr. Clark with her own book on display in the Aquarium’s Shark Lab

Eugenie Clark, Ph.D

Born in New York 1922, age 88. She is known as the top shark scientist in the world. In 1955 she founded the famous Mote Marine Laboratory for shark research. 65 years later, she continues even now with her research. In 2008, she received an Explorer’s Club Medal for her field studies. Her connection with Japan is deep, her mother having been born in Tokyo.

<Eugenie’s comments about the Aquarium>

“Okinawa Churaumi Aquarium is certainly the most beautiful aquarium in the world that I have ever seen or read about. I am greatly impressed with the health and beauty of the live specimens on display and the many rare species of fish – e.g., two guitarfish, Rhina, and “Uchiwa fugu”, Triodon macropterus, for me one of the rarest deep-water fish. I had only studied dead preserved specimens of these before, and now for the first time to see them alive yesterday was incredible and wonderful. This unique Churaumi Aquarium has a constant supply of healthy fresh sea water from the adjacent sea, the main feature for the good condition of all the creatures on display. The wonderful whale sharks and manta rays are most impressive for all of us ―children, laymen and scientists―who visit Churaumi Aquarium. So many “firsts” are here, such as the first baby manta born in captivity.”  

We are grateful for Dr. Clark’s visit. We are inspired not only to keep up our high standards of keeping and exhibiting marine creatures but also to continue with our important marine research.

Contact us

Okinawa Churaumi Aquarium
424 Ishikawa, Motobu-cho, Kunigami-gun,
Okinawa Japan 905-0206

  • TEL:+81-980-48-2742
  • FAX:+81-980-48-4399

Aquarium 8th Anniversary ended on a High Note

2010,11,4 category:Report

On November 1, 2010, Okinawa Churaumi Aquarium celebrated our 8th Anniversary.
It was a great moment and a wonderful “turning point” for our Aquarium.
Thanks to all of you, we had such an important anniversary again.

Therefore, we presented our original calendar for 2011 free to the first 9,000 visitors who could visit our Aquarium on the day of our 8th anniversary.

The event attracted many visitors, including students on school trips and local families who knew about the event in advance from Okinawan newspapers with a lot of gratitude and smiles in the lobby.
The Aquarium Original Calendar was very popular and we had lot of comments from the visitors like these, “beautiful calendar!!” and “wonderful picture”.
 All of our staff is pleased to hear and know about the comments.

 Thank you again.

Contact us

Okinawa Churaumi Aquarium Management Office
424 Ishikawa, Motobu-cho, Kunigami-gun,
Okinawa Japan 905-0206

  • TEL:+81-980-48-3740
  • FAX:+81-980-48-4444

The “Manatee Feeding Activity” ended on a High Note

2010,9,18 category:Report

  The “Manatee Feeding Activity” was held to raise people’s interest in Manatees, as we don’t get a chance to see Manatees in our ordinary life.
  Around 179 people from across Japan thronged the Manatee Pool during this period.

  “Are Manatees and Dugongs same kinds of animal? ”
We often hear these kinds of question above the Manatee Pool.
So we learned with pleasure about the differences between Manatees and Dugongs including their biology and bodies through the event.
Especially, the picture-card show and puzzles about Manatees were very popular during the event.

Difference between Manatees and Dugongs: tail-shape, head shape, and presence of pectoral fin nails.

  Manatee feeding was held after learning about the differences between Manatees and Dugongs. Participants guessed and chose which vegetables would be their favorite from five kinds of vegetables. And we could observe their physical features like eyes, nose, skin, mouth, pectoral fins with the keepers.

At the end, we explained the present status of damage to aquatic wildlife. For example, sometimes plastic bags are carried away to sea by rain and wind from land. Actually, so many sea creatures (including dolphins and manatees) die by swallowing them by mistaking them for food. In fact, there are sea turtles wrapped in fishing line and manatees injured by boat propellers.

There are so many cases of wild animal damage by humans as you already know. We learned ways to save wild animals with our kindness and correct behavior through the event.

We had a lot of feedback from the questionnaires after the event, like “I won’t pollute the sea with any garbage and I am happy to cooperate in any case of wild animals’ future.” and “It was a precious experience for us.” All this feedback encourages us a lot and it will be our pleasure to inform you more about aquatic wildlife.

We will continue to have events like these in you can feel closer to aquatic wildlife including Manatees and Dolphins like this. We hope you will learn something new every time you visit our facility.

Contact us

Ocean Expo Park
424 Ishikawa, Motobu-cho, Kunigami-gun,
Okinawa Japan 905-0206

  • TEL:+81-980-48-2748
  • FAX:+81-980-48-2749

The “Sea Turtle Exhibit” ended on a High Note

2010,9,17 category:Report

We featured a “Sea Turtle Exhibit” as a special summer event at the Sea Turtle Pool from July 1 to August 31, 2010.
Around 140,000 people from across Japan thronged our Aquarium during this period.
We describe these events to you here with photographs.

The front of the Sea Turtle Pool

The Sea Turtle Exhibit

We were held a Sea Turtle Exhibit to explain turtle classification, biology, morphology, our keepers’ duties and research with photographic panels and specimens.
One hugely popular part of the exhibit was entitled “Case Files from the Sea Turtle Pool” which introduced real events at the facility.

“Explanation of Keepers’ Duties and Research”

“Case File from the Sea Turtle Pool”—This panel showed a real event, with one of our keepers trying to pick up a pair of sunglasses from the bottom of the pool to prevent the death of a sea turtle by swallowing them.

We will continue to show and describe to you the Sea Turtles to you through exhibits like this.

Contact us

Ocean Expo Park Management Center
424 Ishikawa, Motobu-cho, Kunigami-gun,
Okinawa Japan 905-0206

  • TEL:+81-980-48-2748
  • FAX:+81-980-48-2749

A new genus and species of deep-sea crab, ‘Hexagonaloides bathyalis’

2010,8,24 category:Report

We have found a new species and genus of crab, named‘Hexagonaloides bathyalis’which was recently described in a taxonomic journal, by T. Komai, T. Higashiji and P. Castro.

Scientific name: ‘Hexagonaloides bathyalis’

phote credit by T. Komai

This new species belongs in the taxonomic Family of crabs (decapod crustaceans) called Trapeziidae. It is named bathyalis, because it came from deep water. Species in this Family are usually found associated with corals, whether in shallow water or in deep water. For example, all species of Trapezia use pocilloporid corals (Pocillopora, Seriatopora, Stylophora) as primary hosts. Other members of the Family, such as species of Tetralia and Tetraloides use acroporid corals (Acropora). Quadrella species are mostly found on gorgonians and antipatharians.

In May, 2009, this crab was found when Okinawa Churaumi Aquarium was collecting deep-water marine creatures for its exhibits, using gill nets on steep slopes below 200 m. The specimens were found on a rock entangled in a gill net, from a depth of 247 meters, off the coast of Iejima Island, so unfortunately their possible hosts remains unknown. It is a small, pale pink crab, with a body about 5mm across.

Because we could not identify the crabs, we asked specialists in the taxonomy of this group of crabs (Dr. Tomoyuki Komai, Natural History Museum and Institute, Chiba; and Dr. Peter Castro, California State Polytechnic University) for help in identifying them. They turned out to be new!

*Currently, the crabs are not on exhibit.

Authors:Dr. Tomoyuki Komai、Mr. Takushou Higashichi(Aquarium staff), Dr. Peter Castro

Contact us

Okinawa Churaumi Aquarium
424 Ishikawa, Motobu-cho, Kunigami-gun,
Okinawa Japan 905-0206

  • TEL:+81-980-48-2742
  • FAX:+81-980-48-4399

For 8 years straight already!! And we hope our coral colonies spawn eggs and sperm again.

2010,5,29 category:Report

We expect our coral colonies to spawn eggs and sperm around 10:00 p.m. on May 25, 2010 in our Coral Sea Tank.
Spawning lasts for about two hours, with eggs and sperm released in pink bundles about 1 mm in diameter from the mouths of the coral polyps.

【Time of spawning】 22:00~24:00 on May 25, 2010
【 Location 】 Coral Sea Tank at Okinawa Churaumi Aquarium

Every year at Okinawa Churaumi Aquarium, our coral colonies have been spawning eggs and sperm, including in June, 2002 before we opened our facility to the public. It will be the 9th time this year.
We will show you video footage and also exhibit the bundles and larvae of corals which we collect from our tank during from June 1 to 10, 2010.
We would like our study of this year’s spawning event to contribute to improving our ongoing research on coral propagation.

Contact us

Okinawa Churaumi Aquarium Management Office
424 Ishikawa, Motobu-cho, Kunigami-gun,
Okinawa Japan 905-0206

  • TEL:+81-980-48-2742
  • FAX:+81-980-48-4399