Phyla: The Chambered Nautilus

The Chambered Nautilus is practically a living fossil. Many species of nautilus are extinct, with only a few surviving today. This creature has lived unchanged for millions of years. The nautilus is a mollusk and part of the Cephalopod family along with the octopi, cuttlefish, and squid.  Similar to it's relatives the nautilus swims by jet propulsion and can reach a speed of up to 2 knots. It also uses siphons to propel water to escape danger.
     The nautilus spends most of it's time in deep water (usually about 500-600m), but will move to shallower water during the night to feed among coral reefs. Since it is found in deep water most of the time it's eyes, unlike it's brethren, are under developed. They lack lenses, so they see the equivalent of what we see through a pin-hole camera. Because it's eyes are poor, it relies on smell and chemical sensors in it's tentacles to search out it's prey.
     These animals can reach a length of about 8 inches. Although they are similar to squids and octopus they differ in their number and design of tentacles. Some nautilus can have 90 tentacles, which are arranged in two circles.  They also lack suckers.  Lacking suckers may seem like a hindrance but they still catch prey such as shrimp and fish. Once prey is captured they crush it with their parrot-like beak.

The chambered nautilus is named after the compartments in its shell. Each chamber is filled with gas. By using internal tubes the animal can inject fluid into each chamber increasing or decreasing pressure, altering it's buoyancy.

Nautilus reproduce by laying eggs and can take several years to reach sexual maturity. The male has four specialized tentacles by which he transfers sperm to the female. The eggs are usually attached to rocks in shallow water. Once laid, the eggs will hatch within a year. The young are tiny, about an inch in diameter, and carry a seven chambered shell. The young will feed on plankton that it comes across while drifting in currents. It is believed that the nautilus can live for 20 years.

These animals live in the Pacific and Indian oceans. Much is unknown about these animals because they live so deep within the ocean. Nautilus populations are being ravaged by the fishing industry, because of it's beautiful and unique shells. In many areas, it is illegal to fish for or sell nautilus.

Here is a great video of Nautilus behaviour