A Japanese crab, the Heikegani, has a shell closely resembling a samurai’s face. Legend says the crabs are the souls of the fallen Heike samurai who died in a massive battle over the Japanese imperial throne. The battle of Dannoura, immortalized in the Heike Monogatari (the Tale of Heike,) was a pivotal moment in Japan’s history that both established the first shogunate and killed a child emperor.
The Heian imperial court was simultaneously the high and low point of Japan’s aristocracy. It had reached the height of its refinement, but at the cost of alienating the ruling class from the people they supposedly governed. There was an explosion in literature. Poetry flourished, dress was extravagant, and The Tale of Genji, one of the world’s first novels, arose from the Heian court. Japan also discovered Buddhism during this time. Unfortunately, the court’s preoccupation with the arts allowed lower-ranking officials and their families to gain the real control over Japan. The two largest families were the Taira (later known as Heike,) who the fated Heikegani crabs are named after, and the Minamoto, later called the Genji.
The heikegani crab’s legend finds its roots from the two rival families’ involvement in Japan’s government, which eventually toppled the imperial courts’ power. After a fierce battle between the two opposing samurai factions, the Heike seized control of Japan. Their leader though, Kiyomori Taira, was in love with his rival’s, Yoshitomo Minamoto, concubine. At her behest he showed an uncharacteristic degree of mercy by sparing her and Minamoto’s sons. Though it might be considered noble by modern standards–especially since killing them was legally permitted–it was ultimately a mistake that would later put and end to the Heike samurai.
Years later those very sons led an uprising against him after he installed his own grandson as the new child emperor. Genji forces drove the Heike out of the capital and proclaimed their own emperor. Their forces pursued the fleeing Heike samurai and the rival emperor to the Shimonoseki straight, were a final, decisive naval battle ensued. The Heike were outnumbered three to one, and the battle was quickly over. The emperor was drowned by his grandmother, who promised him a new kingdom under the sea. The Heiki samurai were either killed or committed suicide by drowning themselves along with their emperor–their dead bodies food for the heikegani crabs.
In the aftermath of the battle, the leader of the Genji, Minamoto Yoritomo, became the first shogun to realize complete military control of Japan. The fate of the remaining Heike was execution–this time without exception. It’s said the Heike samurais’ angry spirits were reincarnated into the heikegani crabs who ate their remains, their scowling faces now marking their carapaces.
Carl Sagan theorized that the crabs’ samurai faces are the result of artificial selection. He proposed the fishermen fishing Japan’s waters would throw back any crabs whose shells looked like a samurai’s face out of respect for the fallen heike. This preserved the DNA of the heikegani with samurai-like faces while thinning the genetic lines of those without.
But, while it certainly is an interesting theory, it’s likely only a bit of scientific folklore. The snarling samurai face on the heikegani’s shells is the result of nothing more than the natural site of muscle attachments. The crabs are only around four centimeters and not used for food, making the theory that fishermen threw samurai face-bearing heikegani back while keeping those without extremely unlikely. Other crabs with human-like shells have also been found throughout the world, even appearing in the fossil record, lending even less credit to the still fascinating theory.
The reason people see a face in the crabs is because of a psychological phenomena called pareidolia, which makes vague or random things seem significant. Seeing a samurai face in the shells of crabs–even the Japanese heikegani–is like how we see shapes in the clouds or a man in the moon. (I’ve never quite been able to see a man in the moon, by the way. I tend to side with the Japanese, who say it’s a rabbit.)
But the legend of the samurai crabs has turned them into souvenirs for the historically-minded travel. And the heikegani’s shells certain do look like angry samurai faces. Maybe the vengeful ghosts of the heike are expressing themselves through the snarling shells of the heikegani.