This type of consistent adaptation between two species is known as?

Chocolatey-brown zebra stripes adorn the nautilus's smooth, white shell. It expands its living space as it grows, adding internal chambers in a perfect logarithmic spiral coated in mother of pearl. The body is situated in the last chamber, and about 90 slim tentacles and a large eye peer out. The tentacles, which bear little anatomical resemblance to the suckered tentacles of squid, function mainly in smelling and manipulating food. When imperiled by predators, the nautilus withdraws into its armor and seals the door with a tough, leathery hood.