A native of the tropical Pacific, the nautilus is an octopus’ cousin. It has more than 90 tentacles — the most of any cephalopod — which it uses to feel and grope along the reefs for food. Unlike those of other cephalopods, a nautilus’s tentacles have grooves and ridges instead of suckers. These grooves and ridges are coated with a sticky secretion that help the nautilus grip food and pass it to its mouth. A nautilus uses its sharp, beaklike mouth to break food apart, and its radula (a band of tissue lined with tiny teeth) to further shred its food.

To avoid predators by day, nautiluses linger along deep reef slopes as deep as 2,200 feet (700 m). A nautilus uses a hood like a trap door to seal itself inside its shell for protection. At night, nautiluses migrate up to shallower depths of about 230 feet (70 m) to feed and lay their eggs. 

While most cephalopods are fairly short lived, a nautilus may live for more than 20 years, reaching maturity in 12 to 15 years. The female lays relatively few eggs — between 10 and 18 per year. Her eggs take about 12 months to hatch.

A nautilus swims using jet propulsion, expelling water from its mantle cavity through a siphon located near its head. By adjusting the direction of the siphon, a nautilus can swim forward, backward or sideways.

Collectors seek out nautilus shells for their beautiful mother-of-pearl linings and red-striped, cream-colored exteriors. In the past beachcombers gathered only shells, but now demand for perfect shells is encouraging deep-water trapping of nautiluses. Since these animals mature late and produce few offspring, shell collecting results in a significant decline in nautilus (and other mollusc) populations. For this reason, the Aquarium doesn’t sell seashells in its gift shops. In 2017, the chambered nautilus was listed as a threatened species under the Endangered Species Act.

• Nautilus eggs are similar in size, shape and appearance to a bulb of garlic.
• A newly hatched nautilus wears a shell divided into seven or eight small chambers. As a nautilus grows, it gains more living space by building new chambers connected to the old ones; adult shells have 30 chambers.
• The nautilus is the only cephalopod with an external shell. Much like zebras, nautiluses can be individually identified based on their striped shell patterns. Their stripes are fixed, but they stretch out as they grow. In young animals the shells are striped all over.
• The tentacles of a nautilus have no suckers or hooks, but hold prey with a sticky secretion.
• A nautilus may live more than 20 years — a very long time compared to other cephalopods.
• To control its buoyancy, a nautilus pumps fluids in and out its shell chambers, which are connected by a tube called a siphuncle.