How does Karana finally catch the sea devil?

She tied string to a spear, which she struck into the devilfish. As they neared the cave, the devilfish turned in a wide circle. Karana pulled it onto land. Rontu got in the way and grabbed hold of the fish. It was about to pull Rontu into the water when Karana stepped between the devilfish and the water, where she stuck her knife she had carved many times into the fish, it got hold of Karana, but the grip lessened and the devilfish was finally dead.