Jaws- Electromagnetic Senses

Her eyes were black,
flat, and unblinking, giving her an air of profound
wisdom. Her pupils were mirror-polished inside, so
she had excellent vision even in this dim light. But
she continued to navigate as before, blindly and
mindlessly as a computer would, using the electro-
receptor ampullae which covered her head to sense
the orientation of the earth’s magnetic field.

- Jaws 2, Chapter 1