There is also a crab in Greek Mythology
KARKINOS (Carcinus) was a giant crab which came to the aid of the Hydra in its battle with Herakles at Lerna. The hero crushed it beneath his foot but as a reward for its service the goddess Hera placed it amongst the stars as the constellation Cancer.
Pseudo-Apollodorus, Bibliotheca 2. 77 - 80 (trans. Aldrich) (Greek mythographer C2nd A.D.) :
"For his second labour Herakles (Heracles) was instructed to slay the Hydra Lernaia (Lernaean). The beast was nurtured in the marshes of Lerna . . .
[Herakles attacked her and] she hung on to him by wrapping herself round one of his feet, and he was unable to help matters by striking her with his club, for as soon as one head was pounded off two others would grow in its place. Then a giant crab (karkinos) came along to help the Hydra, and bit Herakles on the foot. For this he killed the crab."
Plato, Euthydemus 297c (trans. Lamb) (Greek philosopher C4th B.C.) :
"[Plato uses the myth of the Hydra as a metaphor for urgument :] Herakles, who was no match for the Hydra . . . who was so clever that she sent forth many heads . . . in place of each one that was cut off; . . . [and a] crab . . . from the sea--freshly, I fancy, arrived on shore; and, when the hero was so bothered with its leftward barks and bites, he summoned his nephew Iolaus to the rescue, and he brought him effective relief."
Pseudo-Hyginus, Astronomica 2. 23 (trans. Grant) (Roman mythographer C2nd A.D.) :
"Cancer. The Crab is said to have been put among the stars by the favour of Juno [Hera], because, when Hercules [Heracles] had stood firm against the Lernaean Hydra, it had snapped at his foot from the swamp. Hercules, enraged at this, had killed it, and Juno [Hera] put it among the constellations."
Zodiac sign Cancer is a Crab
The Mythology of Cancer
In most myths, Cancer was identified by the giant crab that Hercules (Greek mythology) stepped on and killed while fighting the Hydra. Never was there a more pathetic character in all of mythology. The crab literally pinches Hercules' toe, to which Hercules just crushes him, and that's the end of that. Supposedly the Greek goddess Hera felt bad and put him in the sky.
Sad.
And quite frankly, not a very good story. Luckily, I was able to find a rare but different version. Here we get a brand new look, and honestly, a much better explanation behind the mythology of Cancer.
According to the this myth, a giant crab named Crios guarded the sea nymphs in the Greek god Poseidon's kingdom. He was enormous and strong, and Poseidon himself had blessed him with immortality.
When the god of monsters Typhon (Greek mythology) terrorized the gods of Olympus, Poseidon, along with most of the other gods, went into hiding. He left Crios in charge of protecting the sea nymphs, who were considered to be Poseidon's daughters. The crab took his role as protector very seriously, and wouldn't let any of the sea nymphs outside of his reach. After a while, some of the sea nymphs became restless, and convinced that they were in no danger from Typhon, escaped into the open sea.
Crios could not chase them as he was charged with protecting the other sea nymphs, so he enlisted the help of the giant squid, Vamari. Little did he know that Vamari (whose name translates to "Vampire Squid") had ill intentions, and when he caught up to the sea nymphs, he devoured them.
When Vamari returned to Crios, he told the crab that despite a valiant effort, he could not find any of the missing sea nymphs. Crios knew that he was lying and attacked him. They battled for hours until the crab finally won. But he had sustained such bad injuries that he was terribly crippled from that time forward. Since he was immortal, though, he could not die, but had to live in pain.
When Poseidon returned he saw the bravery that the crab had shown and relieved him of his pain, but not his immortality, by placing him in the sky as the constellation Cancer.
There is also
AI-APAEC
Incan Supreme God
Also known as AYAPEC, APAEC, CRABMAN
Mysterious Creator Crab of Decapitation
He is a fanged supreme being with an air of mystery. Once upon a time, the Moche civilization covered about 750 miles of the coast in Northern Peru. One day it vanished. (Okay, maybe it wasn’t a day — it might have been several years. No-one knows.) The Moche people left many amazing pieces of pottery and artifacts. Amongst them was the Crabman AI-APAEC.
His effigy is a bit battered, but in his former glory he must surely have had great significance. (And he has been discovered again after all these years, so who knows?)
He appears to be a God of Decapitation — several other depictions show him holding a knife in one claw and a severed head in the other. We are not sure if this is a morale-boost for Moche warriors going into battle or a dire warning not to play with crabs.
He likes wearing scary accessories, but seems to be somewhat remote. We suspect he is just shy and the fangs, jaguar heads and snakes are just to keep people from getting too close.
Meanwhile, it seems AI-APAEC is only a part-time crab. He has also been seen in spider and octopus form. What this all means is currently beyond our comprehension.