Bulls are sacred to Zeus
The Bull is an animal sacred to Zeus. It is also the form he took to abduct Europa in the famous story "The Rape of Europa"
The Rape of Europa[]
Upon once again being struck with one of Eros' arrows, Zeus spotted the princess Europa. He approached her and some of her handmaidens in the form of a Bull. All appeared afraid of the bull except Europa. To prove her fearlessness Europa sat on the bull. As soon as she was on his back Zeus ran to the sea and swam to the island of Krete. Once at Krete Zeus revealed his true form and made love to Europa. Europa would become the first queen of Krete.