When it comes to a living system the nuclear submarine is the pinnacle of technology. In a strong sense any nuclear submarine mimics a living system. I.e. the submarine must provide energy to accomplish propulsion, electricity, Life support, external sensing, emergency systems, and weapons systems among other critical auxiliary functions.

The crew of a sub is diversified into several specialty class of operators each trained and tailored to a specific operational function to ensure smooth operations, the crew is further divided by hierarchy i.e. officer and enlisted personnel.

Here is a brief summary of some of the critical submarine functions:

Reaction: The submarine is powered by a nuclear reactor. To start the reactor control rods are drawn to start a chain self sustaining fission reaction that produces heat energy. The heat energy is transformed into steam through a primary secondary loop interface the steam generator. The steam then powers both electrical turbines for electricity and propulsion turbines for propelling the sub.

Life Support: Nuclear submarines can stay under water for extended periods of time up to a month or greater if necessary. To accomplish this feat the sub most produce its own oxygen and must remove the poisonous human byproduct gases. The production of oxygen is accomplished through the process of hydrolysis. The oxygen is then pumped and stored in tanks and then bleed back into the sub to match consumption rate and h2 is discharged overboard. Drinking water also must by distilled form seawater.

Sensing: Submarines fly underwater essentially blind from a visual point of view. However, the sub can navigate through dead reckoning, plotting and or by computer position analysis. Sonar can provide an audible picture of the submarines underwater surroundings while radar, when surfaced, can provide an extended visual overview of the submarine external environment. Additionally when surfaced submarines navigational gear can triangulate with satellites to calibrate navigational computers.

Psychology: When living in cramped quarters with long hours of work and short hours of sleep the crew must communicate effectively to ensure psychological barriers do not interfere with the subs mission.

Weapons: Submarines are designed for warfare hence; they carry both offew3nsive and defensive weapons. Some of the weapons include mk-xxx torpedoes, tomahawk missiles, nuclear missiles.

All in all, the submarine is one large living cell designed for warfare. Depending on the class of a submarine, in the 1980's, it was rumored that submarines had speeds in excess of 25 submerged knots and could obtain depths of greater than 750 feet. Some of the missions of submarines include aircraft carrier escort duty, spying and hunt and kill.