This is the Tiger-striped Nautilus (Nautilus pompilius), sometimes known as the Chambered Nautilus. It is one of the most iconic marine animals, instantly recognisable by its beautifully spiralled shell with distinctive reddish-brown or tiger-like bands. The Tiger-striped Nautilus is a species of cephalopod, related to squids, cuttlefish, and octopuses, but uniquely possessing a prominent external shell.

Location:
Indo-Pacific region—particularly around Australia, Indonesia, Papua New Guinea, and the Philippines. It inhabits deep slopes near coral reefs, typically at depths between 100 and 500 metres, ascending to shallower waters at night to feed.

Average Size:
Shells typically reach up to 20–21 cm in diameter.

Family:
Nautilidae (Chambered Nautiluses)

Species:
Nautilus pompilius (sometimes confused with closely related species such as Nautilus belauensis or Nautilus stenomphalus).

Shell Characteristics:
The shell forms a logarithmic spiral with multiple internal chambers. As the nautilus grows, it moves forward into larger chambers, sealing off the older ones. By regulating the mixture of gases and fluids within these chambers via a specialised structure called the siphuncle, the nautilus controls its buoyancy, allowing it to move efficiently through the water column. The outer surface is marked with striking reddish-brown, flame-like stripes.

Ecological Role:
The Tiger-striped Nautilus is a scavenger and opportunistic predator, feeding on crustaceans, fish, and carrion. By playing a role in nutrient recycling on the reef slopes, it contributes to the health of benthic ecosystems.

Reproduction:
Nautiluses reproduce slowly, laying large, leathery eggs attached to rocks or other hard surfaces. Embryonic development is lengthy—lasting up to 12 months—and juveniles hatch fully formed. Females produce relatively few eggs over their lifetimes.

Conservation Status:
Nautilus pompilius is listed under CITES Appendix II and as Vulnerable on the IUCN Red List due to overharvesting for the ornamental shell trade. Conservation efforts focus on regulating trade and protecting key populations.