is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

native to

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

, with a shell that bears a pattern resembling a human face (a case of

pareidolia Pareidolia (; ) is the tendency for perception to impose a meaningful interpretation on a nebulous stimulus, usually visual, so that one sees an object, pattern, or meaning where there is none. Common examples are perceived images of animals, ...

) which is interpreted to be the face of an angry samurai hence the nickname samurai crab. The crabs are named after the once powerful

Taira clan The Taira was one of the four most important clans that dominated Japanese politics during the Heian, Kamakura and Muromachi Periods of Japanese history – the others being the Fujiwara, the Tachibana, and the Minamoto. The clan is divided ...

which dominated medieval Japan, commonly known as the Heike. It is believed that these crabs are

reincarnation Reincarnation, also known as rebirth or transmigration, is the philosophical or religious concept that the non-physical essence of a living being begins a new life in a different physical form or body after biological death. Resurrection is a ...

s of the Heike warriors defeated at the naval

Battle of Dan-no-ura The was a major sea battle of the Genpei War, occurring at Dan-no-ura, in the Shimonoseki Strait off the southern tip of Honshū. On April 25, 1185 (or March 24, 1185 by the official page of Shimonoseki City), the fleet of the Minamoto clan ...

as told in ''

The Tale of the Heike is an epic poetry, epic account compiled prior to 1330 of the struggle between the Taira clan and Minamoto clan for control of Japan at the end of the 12th century in the Genpei War (1180–1185). Heike () refers to the Taira (), ''hei'' being ...

''. While the crabs are edible, they are not eaten by most Japanese.

Origin of the carapace pattern

Heikegani were used by

Carl Sagan Carl Edward Sagan (; ; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist, cosmologist, astrophysicist, astrobiologist, author, and science communicator. His best known scientific contribution is research on ext ...

in his popular science television series '' Cosmos: A Personal Voyage'' as an example of unintentional

artificial selection Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant m ...

, an interpretation originally published by

Julian Huxley Sir Julian Sorell Huxley (22 June 1887 – 14 February 1975) was an English evolutionary biologist, eugenicist, and internationalist. He was a proponent of natural selection, and a leading figure in the mid-twentieth century modern synthesis. ...

in 1952. According to this hypothesis, the crabs with shells resembling samurai were thrown back to the sea by fishermen out of respect for the Heike warriors, while those not resembling samurai were eaten, giving the former a greater chance of reproducing. Therefore, the more closely the crabs resembled a samurai face, the more likely they would be spared and thrown back. This idea has met with some skepticism. Joel Martin for instance notes that humans do not eat Heikegani, and as such there is no artificial pressure favoring face-like shell patterns, contrary to Sagan's implication. The pattern of ridges on the

carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...

serves a very functional purpose as sites of

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...

attachment. Similar patterns are found on the carapaces of other species and genera throughout the world, including numerous

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

taxa.

Battle of Dan-no-ura

The

was preceded by an immense struggle between the imperial rulers of Japan, the

(also known as the Heike), who the Heikegani crabs are named after, and the

Minamoto clan was one of the surnames bestowed by the Emperors of Japan upon members of the imperial family who were excluded from the line of succession and demoted into the ranks of the nobility from 1192 to 1333. The practice was most prevalent during the ...

(Genji), who were fighting for control of the throne at the end of the 12th century in the

Genpei War The was a national civil war between the Taira and Minamoto clans during the late Heian period of Japan. It resulted in the downfall of the Taira and the establishment of the Kamakura shogunate under Minamoto no Yoritomo, who appointed himself ...

(1180–1185).J. W. Martin (1993): "The Samurai Crab". pg 30-34. On the 24th of April, 1185 AD, two powerful Samurai clans fought to the death on the Dan-no-ura bay of Japan's Inland Sea. The ruling Taira clan (Heike) was led by their child-Emperor, Antoku, and his grandmother,

Taira no Tokiko was a Japanese aristocrat from the Heian period. She was the concubine of Taira no Kiyomori, mother of Taira no Tokuko, and grandmother of Emperor Antoku. Later she took the vows to become a nun, after which she was generally referred to by her B ...

. The Heike had ruled Japan for many decades, but now, massively outnumbered, they faced defeat at the hands of the Minamoto. During the battle, Tokiko took the seven-year-old Emperor Antoku and leaped with him into the water in the Shimonoseki Straits, drowning the child emperor, rather than allowing him to be captured by the opposing forces, and most members and generals of the Taira clan followed them in despair. Antoku came to be worshipped as Mizu-no-kami ("god of water"). This crucial battle was a cultural and political turning point in Japanese history: Minamoto Yoritomo became the first

Shōgun , officially , was the title of the military dictators of Japan during most of the period spanning from 1185 to 1868. Nominally appointed by the Emperor, shoguns were usually the de facto rulers of the country, though during part of the Kamakur ...

, or military ruler, of Japan. Dan-no-ura marked the beginning of seven centuries during which Japan was ruled by warriors and Shōguns instead of Emperors and aristocrats.

Cultural references

In '' Kwaidan: Stories and Studies of Strange Things'', the writer,

Lafcadio Hearn , born Patrick Lafcadio Hearn (; el, Πατρίκιος Λευκάδιος Χέρν, Patríkios Lefkádios Chérn, Irish language, Irish: Pádraig Lafcadio O'hEarain), was an Irish people, Irish-Greeks, Greek-Japanese people, Japanese writer, t ...

, references the Heiki crab in "The Story of Mimi-Nashi-Hoichi." In the 1964 Japanese anthology film,

Kwaidan is a Japanese word consisting of two kanji: 怪 (''kai'') meaning "strange, mysterious, rare, or bewitching apparition" and 談 (''dan'') meaning "talk" or "recited narrative". Overall meaning and usage In its broadest sense, ''kaidan'' refers ...

, based on Hearn's stories, "Hoichi the Earless" recounts the story of the

, which becomes the basis of "Hoichi the Earless." The narrator explains the myth, illustrated with prominent footage of the crabs. At the end of the "Hoichi the Earless" segment, Hoichi is seen playing the lute, with heikegani on his shoulders. In his 1980 science series '' Cosmos: A Personal Voyage'',

used heikegani to illustrate

. British biologist

Richard Dawkins Richard Dawkins (born 26 March 1941) is a British evolutionary biologist and author. He is an emeritus fellow of New College, Oxford and was Professor for Public Understanding of Science in the University of Oxford from 1995 to 2008. An ath ...

discussed the same idea in his 2009 book '' The Greatest Show on Earth: The Evidence for Evolution''.

References

External links

Heike Ichizoku no Onryo – The Vengeful Ghosts of the Heike Clan
at hyakumonogatari.com (English). {{Taxonbar, from=Q1594629 Crabs Crustaceans of Japan Crustaceans described in 1824