- The Nautilus, from the Greek Nautilos for sailor, is a marine mollusc whose tubular shell has barely evolved in 500 million years, and is sometimes referred to as a ‘living fossil’.
- It has two eyes and a beak, but unlike its relatives in the Cephalopod family, the Nautilus has about 90 small tentacles instead of the 8-10 tentacles of the octopus, squid and cuttlefish.
Habitat
- The Nautilus lives at depths of 300-2,300 ft (100-700m) on coral reefs in the Indian and Pacific Oceans between equatorial Latitudes of 30° N and 30° S and Longitudes of 90°-175° East.
- Fishing of the Nautilus species is regulated under Appendix II of the Cites Treaty.
- The shell of a Nautilus follows a constant angle in a logarithimic spiral, but it is not the Golden Ratio.
Lifecycle
- They start to reproduce after 15 years and lay eggs once a year which they attach to rocks. The eggs take up to one year to hatch. They grow to reach 8-10 inches (20-25cm) in diameter.
- They are scavengers and eat carrion.
- The Nautilus lives to be about 20 years old.
Propulsion
- The Nautilus can withdraw inside its shell and seal it with a protective cover. It moves by jet propulsion.
Buoyancy
- The shell of the Nautilus contains 30 chambers, which are used for buoyancy.
- A tube called the Siphuncle connects all the chambers.
- It rises by filling the chambers with gas and sinks by filling them with water.
The Indo-Pacific Ocean