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The Story Behind the Samurai Faced Heikegani

Mamerto Adan is a feature writer who is back in college once again. Science is one of his favorite topics.


Sea creatures could take on strange shapes. While watching episodes in nature shows (National Geographic Channel and Discovery), it’s not uncommon for us to see oddities in oceans and seas. You don’t need to look for cryptids to find nature’s weirdos. Evolution gave these creatures unworldly appendages. I mean oarfishes are harmless, but I won’t get close to that 20-foot elongated sea serpent look-alike. Then, there is the wolf eel. They taste great, and resemble a mythical snake with human head.

And now that we talk about sea creatures with human features, a certain species of Japanese crab might arouse curiosity. For one thing, it’s small and might appear as unimpressive to some people. Being tiny also discourage some to harvest the said crab for food, although the crabs are edible. It’s the shape of its carapace that will catch an observer’s eye.

Upon looking at the carapace, it will give an impression that the crab is scowling back at the observer. Because the crab has the face of an angry samurai. In fact, it is known as heikegani in Japan, or simply heike crab. And the sea creature was linked to a historical battle that became an important turning point in the history of Japan.

The Heikegani

The heikigane, a scowling crab.

The heikigane, a scowling crab.

Crabs with carapace shaped like human faces could be found all over the world, but the heikegani is unique for its resemblance to a snarling samurai. Some observers noted that a charging samurai will come in mind upon seeing the crab, but some people agreed that a samurai menpo is closer. Menpo, or Men-yoroi were Japanese war masks, worn by the samurai as part of their battle armor. It offers protection to the face, and help secure the helmet. The menpo were also painted in dark colors, and given ferocious, or demonic features to frighten the enemy. And going back to the heikegani, the characteristics of the carapace is comparable to a menpo, down to the fearsome expression. Whether it resembles a real face, or a menpo, the heikegani earned the nickname “samurai crab.”

In terms of size, the crab is miniscule, especially when compared to other crab species. The carapace only measures 1.3 inches, with the whole crab itself is smaller than a tarantula. The face-like bumps on the other hand serve an important function. The shell patterns act as attachments for muscles. Nevertheless, scientist Carl Sagan theorized that the unique carapace helped the crabs survived being turned to seafood, thus an example of artificial selection.


Pareidolia  at work.

Pareidolia at work.

Before we explore Carl Sagan’s artificial selection theory of the samurai crab, seeing the crab as a samurai warrior is an example of pareidolia. Pareidolia is the tendency of our brain to impose meaningful interpretations to perceptions. The most common example is interpreting random objects as faces or animals, especially if the feature of the said object seems to form eyes, nose and mouth. That is why we see the Man in the Moon. The samurai face on the shell of the heikegani is no exemption. But as what Carl Sagan hypothesized, the crabs with samurai faces on their shells were thrown back to the sea by Japanese fisherman out of respect, hence helping them to flourished. Such is an example of artificial selection. The hypothesis was challenged though. The heikegani is edible, but small with little meat. Why would people waste their time digging into the shell of heikegani to eat the little flesh it got? This gave the heikegani little market value, and being not considered a delicacy, it is thrown back to the sea when caught.

There is not much to eat in the heikegani, but locals believe that the crabs got their faces as a result of an important sea battle between two samurai clans. As the sayings goes, the crabs are reincarnated spirits of the fallen warriors of the Battle of Dan-no-ura. The soldiers of the Taira clan, also known as the Heike.

The Genpei War

Armor in Genpei War.

Armor in Genpei War.

Going back in 1180s Japan, during the late Heian period, there was an ongoing power struggle between two powerful factions. The clans Taira (Heike) and Minamoto (Genji) are lock in a battle that lasted for five years (1180–1185), known as the Genpei Kassen (Genpei War). Before that, the clans were already in conflict over dominance in the imperial court and the Genpei War eventually broke following a coup initiated by the Taira.

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The clans were the result of demotions in the Imperial family. Whereas the Imperial court became too large and the emperor issued an order that descendants of previous emperors could no longer become princes. Instead, they will carry the noble surnames and ranks. These resulted to establishment of important clans; Taira, Fujiwara, the Tachibana, and the Minamoto. And going back to the start of Genpei war, the actions of then military leader Taira no Kiyomori such as putting his grandson on the throne provoked Emperor Go-Shirakawa's son Mochihito to call for arms. He supported the Minamoto clan in their struggle against the Taira, and in turn gained support from the Minamoto for his bid in the imperial throne. Fighting then broke, and after a series of battles, the clans took it to the Straits of Shimonoseki in the Battle of Dan-no-ura (1185).

Battle of Dan-no-ura

The illustration of the battle.

The illustration of the battle.

By the time of the Battle of Dan-no-ura, the Taira clan already suffered a series of defeats. They do have more ships, and better understanding of tides than the Minamoto. Plus, the battle was fought in the home territory of the Taira. To inspire the men, the young Taira emperor Antoku together with some retainers sailed with the warriors, bringing with them the Imperial Regalia of Sword, Mirror and Jewel.

The battle opened with rains of arrows from archers from both sides. Using the knowledges of waves, the Taira clan surrounded the Minamoto ships; the naval fleet of Minamoto arrived in masses while the Taira ships were split into squadrons. The ranged assaults eventually gave way to boarding and hand to hand fighting, but the sea tides went against the Taira, literally. The Miyamoto now got the advantage.

Initially, it was thought that the son of a Taira general, Taguchi Shigeyoshi was held hostage by the Minamoto. In reality, he defected, and he revealed the emperor’s ship to the Minamoto. The archers then directed their arrows to the emperor's ship, sending the fleet into chaos. Defeat for the Taira became certain, with many warriors taking their own lives. The young emperor Antoku himself perished after jumping into the sea and drowning himself.


Taira’s bid for power came to an end, with the Minamoto establishing the Bakufu in Kamakura, with the leader Minamoto no Yoritomo becoming the first shogun. The influence of the emperor waned, as the warrior class samurai gained power. Japan became a feudal state, and the emperor won’t regain his authority until seven centuries later. By that period, the samurai warriors and the shoguns ruled Japan.

It was said that the spirit of the Taira warriors lived on and reincarnated as crabs, with their carapaces bearing their faces. In the end, the human faces of heikegani were nothing but muscle attachments, yet it became a reminder of an important battle in the Straits of Shimonoseki, that changed Japan forever.


1. Sagan, Carl (2011). Cosmos. Random House Publishing Group

2. Turnbull, Stephen (1977). The Samurai, A Military History. MacMillan Publishing Co., Inc.

3. Patowary, Kaushik (26 June, 2017). Heikegani: The Crab With A Human Face". Amusing Planet.

4. "...the Gempei conflict was a national civil war" Warrior Rule in Japan, page 2. Cambridge University Press.

5. Sansom, George (1958). A History of Japan to 1334. Stanford University Press.

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