Nautilus (Nautilus pompilius)

Marine invertebrateCephalopodLiving fossil

Overview

The chambered nautilus (Nautilus pompilius) is a striking cephalopod — a relative of octopuses and squid — that, unlike them, lives inside a coiled external shell. Often called a “living fossil,” the nautilus belongs to an ancient lineage whose shelled relatives were once abundant in the oceans, and its body plan has changed relatively little over a very long span of time.

Its smooth, spiral shell is divided into gas-filled chambers that the animal uses for buoyancy, while the living nautilus occupies only the outermost chamber and reaches out with dozens of small tentacles.

Conservation note: nautiluses have been heavily collected for their beautiful shells, which is a conservation concern; the chambered nautilus is protected under international trade rules. Verify current status at iucnredlist.org.

Habitat & Range

Nautiluses live in the deep waters of tropical reef slopes in the Indo-Pacific, typically along the steep faces of coral reefs. They tend to stay in cooler, deeper water by day and move up the slope at night to feed, avoiding both very warm shallow water and the greatest depths.

Diet

Nautiluses are mainly scavengers and opportunistic feeders, eating the moults and remains of crustaceans and other animals, along with some live prey. They locate food largely by smell, sweeping the water with their many tentacles, and have a low metabolism that lets them go long periods between meals.

Behavior

Like other cephalopods, the nautilus swims by jet propulsion, drawing water into the body and expelling it through a funnel to move — usually backwards. It adjusts the gas and fluid in its shell chambers to control buoyancy. Nautiluses have many more tentacles than octopuses or squid (several dozen), but these lack suckers and instead grip with ridges. They are long-lived and slow to mature, which adds to their vulnerability.

Human Interaction & Conservation

The nautilus's spiral shell — famous for its elegant proportions — has made it a target of the shell trade, and combined with the animal's slow reproduction this has raised real conservation concerns, leading to international trade protections. For current status and trade rules, consult authoritative sources such as the IUCN Red List.

More photos of the nautilus