Behold the ocean's version of crop circles. But this wasn't made by aliens or humans pretending to be aliens. A single, small fish made this circle.

Last fall, there were the reports of "mysterious" underwater sea circles, discovered 80 feet below sea level off the coast of Japan. Yoji Okata, an underwater photographer with over 50 years of diving experience, first spotted these geometric sea shapes that can measure over six feet in diameter.

As website Spoon & Tamago reported at the time, nobody had seen anything like them—nor did anyone know that these beautiful shapes were somewhat romantic.

It turns out that small male pufferfish create the circles by flapping their fins and even "decorate" their designs with small shells. The geometric shape attracts a prospective partner, who uses the circle's ridges to find her way through the dark ocean floor.

The two fish then mate, and the female lays her eggs in the circle's center. As Spoon & Tamago points out, it's believed the decorative shells also provide nutrients for the pufferfish's offspring.


Previously, Okata and NHK worked on a TV documentary that showed the creation of these circles. Last Friday, however, the Yomiuri Shimbun reported that there was now a proper scientific paper on the marine pufferfish's unique reproduction.

You can read the paper on, which Okata co-authored and which was published last month.

「ミステリーサークル」…作ったのはフグ [Yomiuri via 2ch]

Photos:Kaikyokan, ダイビング歴50年水中写真家, NHK

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