Chambered Nautilus

Nautiluses are cephalopods—a kind of mollusk. Cephalopod means "headfoot" which reflects their relatively complex brain and the numerous tentacles. Nautiluses are related to squids and octopuses, but are easily differentiated by their distinctive, ornate, coiled shells. 

Although their taxonomy is poorly resolved, the nautilus family, Nautilidae, is currently considered to include seven species in two genera, Nautilus and Allonautilus, all which share the common name, chambered nautilus. 

The chambered nautilus, Nautilus pompilius, is a highly vulnerable species because of its life history characteristics, including low reproductive rates, slow growth, and late maturity. This species is thought to occur in small, isolated populations throughout its range. They are also limited by both depth and temperature tolerances. They have multiple predators, including sharks, bony fishes, and octopuses.

Chambered nautiluses are primarily targeted for their shells, which are sold commercially and traded internationally for use in art, furniture, jewelry, and other items. 

In 2018, NOAA Fisheries listed the chambered nautilus as a threatened species under the Endangered Species Act.

Nautiluses are known for their beautiful, coiled shells. The shell can range in color, from white to orange, and even purple, with unique color patterns. Protruding from the shell are more than 90 suckerless tentacles.

The soft-bodied nautilus lives inside a hard, chambered shell. It uses the chambers to pump air and water in and out of its shell, creating jet propulsion to thrust itself backwards and to make turns. 

They possess a siphon tube, known as a hyponome, which runs the length of the shell. The hyponome allows the nautilus to control its buoyancy by regulating air and water in the shell chambers.

Nautiluses are hunters and pick up food scents in the water column with chemosensors on their tentacles. They consume animals such as fish, crabs, and lobsters with their sharp, beak-like mouth.

Chambered nautilus are mainly found in the western Pacific Ocean and coastal areas of the Indian Ocean. They can also be found in waters off of the American Samoa.

Unlike other cephalopods, nautiluses are relatively long-lived, reaching ages of 15 to 20 years, or more.

They grow slowly, maturing around 10 to 15 years of age, and produce a small number of eggs that require at least a year-long incubation period.

The primary threats to nautiluses include:

• Targeted, market-driven harvest for international trade in their shells.
• Habitat degradation throughout much of their range.

Given their slow growth, late maturity, low reproductive output, and low mobility, chambered nautiluses are particularly vulnerable to overfishing.