{{Use dmy dates|date=October 2021}} {{short description|Animal mating behavior}} The white-spotted pufferfish (''Torquigener albomaculosus'') is known for its unique and complex courtship display. Males create large geometric circles in the sand to attract females for copulation. To construct the ornate circular structure, a male works for more than a week straight. He flaps his fins along the seafloor to build ridges which he then decorates with shells and coral and sculpts a unique maze pattern in the center where a female might lay her eggs if, after evaluating his construction skills, she chooses him.<ref>{{Cite web |date=2013-10-03 |title=Mysterious underwater circles created by 5-inch fish seeking love |url=https://www.nbcnews.com/sciencemain/mysterious-underwater-circles-created-5-inch-fish-seeking-love-8c11329858 |access-date=2025-02-12 |website=NBC News |language=en}}</ref> He guards the eggs until they hatch and does not reuse the circles.
The geometric circles were first noticed by divers in 1995, but it was not known that they were created by white-spotted pufferfish until 2013, when the species was discovered in the Ryukyu Islands. It was thought that white-spotted pufferfish are the only species to engage in this type of mating ritual, although in 2018, similar structures were discovered in Australia which may be built by a different species of ''Torquigener''.
== Discovery == The white-spotted pufferfish is a relatively small ({{Convert|10|cm|abbr=on|disp=or}}) fish that was named in 2014 by a research group for the National Museum of Nature and Science.<ref name=":0">{{Cite journal|last=Matsuura|first=Keiichi|date=1 January 2015|title=A new pufferfish of the genus Torquigener that builds "mystery circles" on sandy bottoms in the Ryukyu Islands, Japan (Actinopterygii: Tetraodontiformes: Tetraodontidae)|journal=Ichthyological Research|volume=62|issue=2|pages=207–212|doi=10.1007/s10228-014-0428-5|issn=1616-3915}}</ref> The fish has a brownish-yellow body with white spots and the ventral part of the body is translucent.<ref name=":0" /> The study specimens were collected off the south coast of Amami Ōshima in the Ryukyu Islands. Naming this species took the genus ''Torquigener'' to a total of 20 species.<ref name="BBC2014">{{Cite web|date=9 December 2014|title=New pufferfish species named|url=http://www.bbc.com/earth/story/20141205-new-pufferfish-named|access-date=22 October 2019|website=www.bbc.com}}</ref>
The species was first discovered to be the manufacturers of highly ordered, large, circular sand structures on the sea floor in 2013. These structures have been observed by local scuba divers since 1995, although it was not yet known how they were formed. In 2012 an underwater photographer observed a pufferfish forming this structure. ''Torquigener albomaculosus'' was thought to be the only species of pufferfish to engage in this behaviour, until similar sand structures were found off the coast of Western Australia beyond {{Convert|100|m|abbr=on}} water depth, which are believed to be pufferfish nests from an uncertain species of ''Torquigener''.<ref name="BBC2014"/><ref>{{cite journal |first1=Todd |last1=Bond |first2=Robert J. |last2=Mueller |first3=Matthew J. |last3=Birt |first4=Jane |last4=Prince |first5=Karen |last5=Miller |first6=Julian C. |last6=Partridge |first7=Dianne L. |last7=McLean |title=Mystery pufferfish create elaborate circular nests at mesophotic depths in Australia |journal=Journal of Fish Biology |date=21 August 2020 |volume=97 |issue=5 |pages=1401–1407 |doi=10.1111/jfb.14506|doi-access=free |pmid=32820821 |hdl=10536/DRO/DU:30148257 |hdl-access=free }}</ref>
== Description == thumb|Movements of the white-spotted pufferfish for nest constructionThese structures are found at depths of {{Convert|10-30|m|abbr=on}} on the seabed off the south coast of the Amami Ōshima Island.<ref name=":0" /> These circular structures are geometrically ordered with a diameter of 2 meters and are formed in 7–9 days. The outer ring of the nest consists of a series of mountains and groves and the center is an irregular maze like pattern. The center is formed with very fine sand particles with respect to the outer portion. It is now thought that they are the most ordered structures created by any fish.<ref name=":1">{{Cite journal|last1=Kawase|first1=Hiroshi|last2=Okata|first2=Yoji|last3=Ito|first3=Kimiaki|date=1 July 2013|title=Role of Huge Geometric Circular Structures in the Reproduction of a Marine Pufferfish|journal=Scientific Reports|volume=3|pages=2106|doi=10.1038/srep02106|issn=2045-2322|pmc=3696902|pmid=23811799}}</ref><ref name=":2">{{Cite journal|last1=Mizuuchi|first1=Ryo|last2=Kawase|first2=Hiroshi|last3=Shin|first3=Hirofumi|last4=Iwai|first4=Daisuke|last5=Kondo|first5=Shigeru|date=17 August 2018|title=Simple rules for construction of a geometric nest structure by pufferfish|journal=Scientific Reports|volume=8|issue=1|page=12366 |doi=10.1038/s41598-018-30857-0|issn=2045-2322|doi-access=free|pmid=30120331 |pmc=6098008}}</ref> Each circle, two meters in diameter, has a huge cost of construction for the relatively small ({{Convert|10|cm|abbr=on|disp=or}}) fish.<ref>{{Cite web |title=BBC Arts - BBC Arts - Sir David Attenborough: Can animals be artists? |url=https://www.bbc.co.uk/programmes/articles/4DNNgJHkQKZM0ghMj0rc8wZ/sir-david-attenborough-can-animals-be-artists |access-date=2025-02-12 |website=BBC |language=en-GB}}</ref>
The fish begins making the structure by forming a simple circle shape in the sand using its belly.<ref name=":2" /> Once this is complete the fish makes the valleys and peaks by waving its fins while swimming in a straight line from the outside to the inside of the nest. The center is formed by either inside to the outside, or outside to inside movements, while waving its anal fin to form the irregular pattern.<ref name=":1" /><ref name=":2" /> Through these movements, very fine sand particles are moved to the center.<ref name=":1" /> Once the structure is completed, it is maintained until spawning by continuing the same inward-outward movements.<ref name=":1" /> After spawning, the structure gradually deteriorates since maintenance behavior is halted.<ref name=":1" />
In a 2014 documentary by the BBC, narrator David Attenborough describes the pufferfish as "dull, almost to the point of invisibility. But to compensate, he is probably nature's greatest artist."<ref>{{Cite web |date=2017-04-17 |title=This Fish's Weirdly Fascinating Mating Ritual Is Going Viral |url=https://www.countryliving.com/life/kids-pets/news/a42659/japanese-puffer-fish-artwork/ |access-date=2025-02-12 |website=Country Living |language=en-US}}</ref>
== Purpose of the "mystery circles" ==
=== Female choice === This behavior is an example of a mating ritual, because it is used to attract mates and raise their young.<ref name=":4">{{Citation|title=Courtship display|date=27 September 2019|url=https://en.wikipedia.org/w/index.php?title=Courtship_display&oldid=918159938|work=Wikipedia|access-date=13 October 2019}}</ref><ref name=":3">{{Cite journal|last1=Kawase|first1=Hisoshi|last2=Okata|first2=Yoji|last3=Ito|first3=Kimiaki|last4=Ida|first4=Akihiko|date=January 2015|title=Spawning behavior and paternal egg care in a circular structure constructed by pufferfish, Torquigener albomaculosus (Pisces: Tetraodontidae)|journal=Bulletin of Marine Science|volume=91|pages=33–43|doi=10.5343/bms.2014.1055}}</ref> It is assumed that the nest is important in female choice; however, there are no definitive factors known to influence the females' choice.<ref name=":3" /> There are a number of possible factors to consider, such as size and number of peaks/valleys, size of circle, sand composition, and color.<ref name=":1" /> This is also believed to be the most geometrically ordered structure created by any fish.<ref name=":2" /> There is evidence that females may be able to predict male body size and thus health of the fish from the structure formed.<ref name=":2" /> Larger males were shown to push sand further than smaller males, thus making larger spaces between peaks of the outer ring structure than those of a smaller male's nest.<ref name=":2" /> Females may be able to recognize these differences and assess whom she wants to mate with.<ref name=":2" />
In addition to this, two more courtship behaviors are carried out by the males before spawning.<ref name=":3" /> When females approach the nest, the males stir up the sand in the nest, and then perform a rush and retreat behavior to the females.<ref name=":3" /> It is hypothesized that the stirring of the sand is to show females the quality and quantity of the sand in the structure.<ref name=":3" /> For the rush and repeat behavior, the males would move to the outer portion of the nest, then rush towards the females, and then retreat back to the outer ring.<ref name=":3" /> After these courtship behaviors, the female will decide whether or not to spawn.<ref name=":3" />
=== Mating === Spawning occurs from spring to summer.<ref name=":3" /> If a female decides to mate after the male performs the courtship behaviors, she will descend to the floor of the nest and the male will approach her.<ref name=":3" /> Mating occurs in pairs, and they will press their bodies together and vibrate until the female releases her gametes in the nest.<ref name=":3" /> Males may mate with multiple females in one day.<ref name=":3" />
=== Parental care === After mating, the females leave the nest and the males stay.<ref name=":1" /> The males will no longer perform maintenance on the nest once the eggs are deposited.<ref name=":1" /> Males will care for the eggs and protect them until they hatch.<ref name=":3" /> They will chase off predators or other rival males that come to the nest.<ref name=":3" /> Eggs hatch around five days after mating, and the nest slowly deteriorates over this time.<ref name=":1" /><ref name=":3" /> After hatching, males leave and will not use the same nest again.<ref name=":1" />
== See also == *Bowerbird
== References == <references />
Category:Fish reproduction Category:Tetraodontidae