and other members of the family Cymatoceratidae were the most common
nautiloids during the Cretaceous. It is thought that they, like
extant Nautilus, regulated floatation by controlling the
amount of gas in their empty chambers.
Internal septa and chambers can be
seen in this cut specimen. The body of the living animal occupied
the last (and largest) chamber. In a live nautilus, the
chambers are connected by a narrow tube (the siphuncle),
and contain gas or liquid. In some fossil species the chambers were filled with shell. Nautilus has a
lensless eye, and numerous tentacles to capture food. It lives
in fairly deep water, but migrates towards the surface at night in
search of food. It is thought that they track by smell.