The Greek word used for whale in Matt 12:40 is kētos.
[Mat 12:40 KJV] For as Jonas was three days and three nights in the kētos belly; so shall the Son of man be three days and three nights in the heart of the earth.
This is the same word used for the Cetus constellation. Although it’s typically translated whale, the meaning is broader than that. It can mean a large fish, a whale, a shark, or a sea monster. The Greeks depicted Cetus as fish-like and serpentine with a long muzzle fighting Perseus.
“Cetus was commonly depicted by the Greeks as a hybrid creature. It had forefeet, huge jaws, and a scaly body like a giant sea serpent. Even though the constellation is also known as the Whale, the mythical creature in the depictions does not in fact look like a whale.”
“To appease the sea god and the nymphs, Cassiopeia and her husband, King Cepheus, had to sacrifice their young daughter to Cetus, a sea monster sent by Poseidon to punish the king and queen, or watch the monster ravage their land. Andromeda was chained to a rock and left to the sea monster, but to her good fortune, the hero Perseus was passing by just as Cetus was about to devour her. Perseus rescued the princess and killed Cetus. He and Andromeda were later married.”
An alternative theory to the traditional Jonah account is Jonah was lost at sea in the constellation Cetus for 3 days.
Links:
Cetus (mythology)
Jonah’s “Whale†Is a Constellation!
Cetus Constellation