Nautilus

One of the most spectacular and mysterious sea creatures, it has survived nearly unchanged for about half a million years. The nautilus is a shelled marine mollusk that lives in the Pacific and Indian oceans. It has short tentacles used for hunting and a spiral shell that is divided into chambers.

Releasing gas into the chambers allows the nautilus to float at different depths. The nautilus is closely related to the extinct ammonite. However, while the ammonites went extinct during the mass extinction event that took out the dinosaurs 65 million years ago, the nautilus managed to survive to this day.

The way the nautilus sails about the sea was inspirational to many, and many submarines have been named after the animal. The author Jules Verne also named Captain Nemo's submarine "Nautilus" in his book, "Twenty-thousand Leagues Under the Sea". Scientists and marine researchers fear the nautilus population may be facing extinction. The reason for this is demand for their beautiful shells, from which many decorative items are made – plates, necklaces, earrings etc.

Another problem that may accelerate the disappearance of these special creatures is the fact that they grow very slowly, and only reach sexual maturity after 15 years, until which they cannot reproduce.