Chambered Nautiluses: Description & Behavior
The chambered or emperor nautilus (Nautilus pompilius) grows up to 20 cm long. Its spiral shell, patterned in brown and white, contains up to 30 chambers formed as the animal grows, with the outermost chamber housing the body. A special tube, the siphuncle, passes gas between chambers to maintain buoyancy and keep the nautilus upright. Unlike their squid and octopus relatives, nautiluses have around 90 slender, suckerless tentacles and very simple eyes that lack a cornea or lens. They, along with Allonautilus, are the last living genera of externally shelled cephalopods.
World Range & Habitat
Chambered nautiluses inhabit the western Pacific Ocean. They are typically found near the seafloor or around coral reefs at depths of up to 500 m, although they often migrate to shallower waters during the night.
Feeding Behavior
Due to their primitive eyes, chambered nautiluses rely on an excellent sense of smell to locate prey. They feed on small fishes, crabs, and occasionally carrion. Their hunting style is slow and opportunistic compared to faster cephalopods like squid.
Life History
These mollusks are slow to mature, reaching sexual maturity at 15–20 years. Mating involves internal fertilization: males use four tentacles to transfer a spermatophore — a sperm capsule — to females. The coating dissolves, releasing sperm to fertilize eggs. Females lay large eggs, each about 3.8 cm long, which hatch into young with shells about 2.5 cm in diameter. This slow reproduction contributes to their vulnerability in the wild.
