Latest news with #AmamiMarineLifeResearchAssociation
Yomiuri Shimbun
05-07-2025
- Science
- Yomiuri Shimbun
Kagoshima: ‘Mystery Circle' Made by Puffer Fish on Seabed; Males Stir Up Sand to Make Spawning Areas
AMAMI, Kagoshima — A circular geometric pattern was found this year on the seabed off the course of Kagoshima Prefecture's Amami Oshima Island. The 2-meter diameter pattern is a puffer fish spawning bed. The spawning ground was created by a species known as Amami night-sky puffer fish, which themselves measure about 10 to 15 centimeters in length. The pattern, referred to as the 'seabed mystery circle,' was found at a depth of 29 meters by Katsuki Oki, the head of the Amami Marine Life Research Association, among other parties, on June 6. The association conducts research on the ecology of marine life in the waters near the island. According to the association, male puffer fish create these spawning beds by stirring up the sand on the seabed using their fins to draw female fish. On June 7, a female was observed laying eggs at the center of the 'mystery circle.'The male that created the bed would then release sperm there and guard the eggs for about a week until they hatch. This is a common sight each year during the species' spring-to-summer breeding season. 'Their breeding behavior cannot be observed unless their environment is in good order, with sandy, mostly flat seabed with small stones,' Oki said. 'We hope this rare behavior can be carefully observed.'
Asahi Shimbun
12-06-2025
- Science
- Asahi Shimbun
‘Crop circles' made by love-struck pufferfish spotted off island
SETOUCHI, Kagoshima Prefecture—Mysterious geometric patterns dubbed 'underwater crop circles' are appearing on the seafloor as the spawning season of a local pufferfish begins off the southern coast of Amami-Oshima island. The intricate, circular formations are created by male Amami night-sky pufferfish as part of their elaborate courtship ritual. On June 7, Katsuki Oki, head of the Amami Marine Life Research Association, captured rare footage of this unusual behavior in the Oshima Strait at a depth of 29 meters. According to Oki, a male pufferfish had completed the artful sand structure the day before. During filming, a female entered the center of the circle to spawn. In a brief but intimate moment, the male pressed close to the female, appearing to nip at her as he released sperm to fertilize the eggs. The male will guard the eggs, laid in the central basin of the circle, until they hatch about a week later. 'The fish is a charming and symbolic species that represents the marine biodiversity of the island,' said Oki. 'Its unique spawning behavior is captivating and beloved. It's something we should all strive to protect.' A fully grown Amami night-sky pufferfish measures about 15 centimeters in length. The species gets its name from the star-like speckles on its back. The fish are found primarily around Amami-Oshima island and are also believed to inhabit the nearby waters off Okinawa Prefecture. However, the elaborate geometric spawning nests have only been confirmed off Amami-Oshima. Local tour operators offer diving tours to observe these remarkable underwater structures during the spawning season, which runs from April to July.
