Japan’s white-spotted pufferfish are renowned for producing complex, ringed patterns in the sand. Now, 5,500 kilometers away in Australia, scientists have discovered what appear to be dozens more of these creations.
While conducting a marine life survey out on Australia’s North West Shelf near subsea gas infrastructure with an autonomous underwater vehicle, marine ecologist Todd Bond spotted a striking pattern on the seafloor, more than 100 meters deep. “Immediately, I knew what it was,” recounts Bond, of the University of Western Australia in Perth. Bond and his colleagues continued the survey, ultimately finding nearly two dozen more.
Until now, these undersea “crop circles” were found only off the coast of Japan. First spotted in the 1990s, it took two decades to solve the mystery of what created them. In 2011, scientists found the sculptors — the diminutive males of what was then a new species of Torquigener pufferfish. The patterns are nests, meticulously plowed over the course of days and decorated with shells to entice females to lay their eggs in the center.
A hovering autonomous underwater vehicle (HAUV) deployed along subsea natural gas infrastructure off Australia’s coast in September 2018 captured footage of something surprising: a rippled ring carved into the sand.
Researchers eventually discovered nearly two dozen of these circles, similar to the elaborate nests crafted by white-spotted pufferfish males near Japan, making it the first such find outside Japan. While it’s not known what species created the Australian rings, an unidentified pufferfish was seen fleeing the site of one of them.
While there’s no video confirmation that pufferfish are building the nests in Australia, the structures are nearly identical to those in Japan, even sharing a similar number of ridges, Bond and his colleagues report in the November 2020 Journal of Fish Biology.
And when a colleague deployed an underwater video system in the area, the contraption luckily landed almost directly atop a circle and captured footage of a small pufferfish fleeing the formation.
“It is surprising to find the circles … at a depth where there is not much light,” says Elisabet Forsgren, a behavioral ecologist at the Norwegian Institute for Nature Research in Trondheim. If the nests are meant to be a visual signal to attract females, they may be hard to see in such a dim spot.
Bond says that the discovery raises more questions that may ultimately help us understand the evolution of pufferfishes, a group already awash in eccentricities.
Not only are they among the most toxic vertebrates on Earth, but they’ve completely lost their ribs and pelvic bones to make room when they “puff” with water (SN: 8/1/19). Among the questions: If the Australian circles are made by a different species from Japan’s, did the two fishes’ artistic skills evolve separately?
“It’s kind of humbling to know that there’s so much out there that we don’t know,” says Bond. “It’s also a little bit scary as well. This is a reflection of, obviously, a key part to the reproduction of maybe a new species, but we just know nothing about it. We didn’t even know these existed.”
Originally published at Science news