CEPHALOPODS

THE ONLY CEPHALOPODS with true external shells are the nautilus shells.
Once they were one of the most dominant invertebrates in the sea; now only
a few species survive in the Indo-Pacific region. The lightweight shells have
chambers filled with a gas which helps them control their buoyancy.

Subclass: NAUTILOIDEA Family: Nautilidae

Species: Nautilus pompilius Linnaeus

  CHAMBERED NAUTILUS

A lightweight, thin-shelled species, it is spirally coiled, but this is only obvious
when the shell is sectioned. The shell is also partitioned; the resulting chambers
are connected to each other by a hollow tube. It is bilaterally symmetrical,
with a large aperture but no umbilicus.

White or creamy colour, with zebra-like, reddish stripes radiating from the
umbilical region though not extending onto the broadest part of the body whorl.

HABITAT: Free swimming.

Range: Indo-Pacific waters mainly

Occurrence: medium

Size: 15 cm (6 in)