Cybernetically augmented space cockroaches.

[hider=Kakerlak Species Info]

[hider=Culture] Kakerlakes, while not overly aggressive, have little regard for the safety of themselves or those around them—the thralls simply don’t care, the journeymen don’t know any better, and the patriarchs are effectively immortal.
The patriarchs behave less like a ruling body and more like a bunch of old war buddies on an extended camping trip.  They have considerable interest in the culture, technology and food of other species.
Thralls lack initiative, and will obey the commands of anyone who is convincing enough.  Journeymen aren’t quite as foolish but are imprinted to be loyal to the patriarchs.[/hider]
[hider=History] Kakerlake are evolved from a cockroach-like species that infested a generation ship some millions of years ago.  The ship’s original crew perished some generations into their voyage, and were kind enough to sabotage the radiation shielding before they died.  Only some plant life and pests survived the radiation, and as the ship drifted through space they evolved to match their environment.  Gradually, the Kakerlakes developed an instinctual understanding of tools sophisticated enough to maintain and even repair portions of the generation ship.
The ship drifts for millions of years, and eventually encounters other alien life.  The Gedune uplift the Kakerlakes, augmenting some of their number with cybernetic computer systems, granting them long-term memory.  The first augmented Kakerlakes turned out to be skilled negotiators with little regard for their unaugmented brethren, and promptly sold many of the thralls aboard into slavery in exchange for the repair and refit of their ship.  These twenty-eight augmented Kakerlakes formed the Patriarchy of Babel, and continued on their merry way.[/hider]
[hider=Physiological Description]
[img]http://stylishwebdesigner.com/wp-content/uploads/2010/07/9e1242729e408e185a334c5b0df2f29a.jpg[/img]

The Kakerlak are evolved cockroaches, 3-4 feet in length.  They have a maximum lifespan of around a decade. 
Like normal cockroaches (but more so), Kakerlake are almost immune to radiation, able to survive thousands of times the radiation a human could.  They can survive hundreds of gravities of acceleration, and are very resilient in general.  They can function in vacuum for more than an hour without oxygen, regenerate lost limbs, and are even receptive to freeze-drying.
Although they have a natural aptitude for tools and language, the average Kakerlak is comparable in intelligence with a dumb human.  Even the smartest could only be considered to be of average intellect by other sentient species.  And all un-augmented Kakerlake have a long term memory that lasts no longer than a week.  Although their instinctual skills make them well suited for the basic operation and maintenance of a spacecraft, without direction they are hopeless.
There are more than six thousand un-augmented Kakerlake (Thralls) aboard [i]Babel[/i].
Because of their resilience and regenerative capabilities, Kakerlake are easy to cybernetically augment.  The thralls are led by journeymen and patriarchs, which are augmented with computer systems which merge seamlessly with the brain.  The computer systems record for and direct the Kakerlak, imparting long term memories and enhancing their cogitation.  Only the smartest among the thralls are typically chosen for cybernetic augmentation, and those gain a plethora of computerized tools to aid them in mathematics, navigation and translation, among other subjects.
Because long-term memory retention is solely the job of the cybernetics, Kakerlakes have attained effective immortality, and can even be transferred from cockroach to shipboard computer.
Patriarch Kakerlakes are old; some have lived dozens of lifetimes.  There are only twenty-eight of them, and not one has yet died a true death.  As the Kakerlake journey between stars, they reside solely within the ship’s computers, except for the one patriarch designated as the Watcher.  During the long journeys through deep space these patriarchs guide their species’ evolution through a mixture of selective breeding and genetic engineering.
Journeymen are young augmented Kakerlakes typically imprinted with only skills, not memories.  They direct the thralls, handle delicate tasks aboard the ship, and generally carry out the demands of the patriarchs.  Lacking the wisdom (and sentimental value) of the patriarchs, journeymen rarely live more than one life.
There are currently only a hundred journeymen aboard [i]Babel[/i], although that number will rise in times of crisis.
Kakerlakes are omnivores, and will eat anything, even dead Kakerlake.  Kakerlake females are smaller than the males and give birth to as many as a dozen egg cases in a single year—each containing 40-60 eggs.  Where space and resources are limited (such as aboard [i]Babel[/i]), the young eat one another until the population crisis is resolved.
Kakerlake exoskeletons are resistant to small arms fire and their underdeveloped wings allow them to, with significant effort, fly under Earth gravity.[/hider]
[b]Summary of Traits:[/b] Very resistant to radiation, vacuum, toxins.  Can withstand tremendous acceleration and are generally very durable.  No long term memory without cybernetic augmentation.  Augmented Kakerlake have a photographic memory.
[/hider]

[hider=The Tower of Babel]
[img]http://i.imgur.com/QnrBVZA.png[/img]
A mere 340 meters long, massing almost 780,000 tons, [i]Babel[/i] is home to an entire species.  Within, six thousand irradiated cockroaches crawl within its empty fuel tanks.  When the ship refuels, they die en-mass, frozen in liquid hydrogen.
The hull is dotted with ferro-thrusters (essentially gauss cannons) which function as high-thrust RCS engines and double as extremely short range weapons.
Between the armored ribs lies the Siphon, which can suck in vast amounts of gas from atmospheres of gas giants or terrestrial worlds.
[img]http://i.imgur.com/cf0e5uA.png[/img]
[i]Babel’s[/i] computer systems are a hybrid of digital and analog technologies—silicon transistors, fiber optic switches and even some mechanical components.  Such is their specialization that these systems are incredibly confusing repair and maintain.
Fortunately, the Kakerlakes who made them yet live and possess photographic memories. [i]Babel’s[/i] computer systems might be slower than those of other spacecraft, but radiation damage and EMP causes only minor and temporary problems.
That, and they're operated by taped recordings of dead cockroaches.
[hider=Engine][i]Babel's[/i] main engine combines all the hazards of the Zubrin Nuclear Salt-Water Rocket and the Nuclear Thermal Gas Core Open-Cycle Rocket, with none of the safety precautions.  A fissile salt is injected into a deuterium bath composing most of the reaction chamber in subcritical densities.  This fuel reaches supersonic speeds as it is pumped through the plenum and reaction mass is added (this can be anything, but denser elements will result in more thrust and less specific impulse).  It begins a thermonuclear reaction within the plenum, although this blast is shaped and contained by the still sub-critical fuel above it.  As the detonating mass is ejected from the nozzle, temperatures and densities cause a chain-fusion reaction (deuterium fuse, creating tritium and helium-3 which fuse creating helium-4).  At a low setting this process is more controlled and nets a higher specific impulse (but less thrust).
Acceleration under normal operation ranges from 10 to 20 G's, but in close proximity to a gas giant [i]Babel[/i] can create a fusion explosion within its atmosphere, resulting in over 100 G's of sudden acceleration.
With a mass ratio of 3, [i]Babel[/i] has nearly 9000 km/s of dV (enough to reach 3% C).
(120 GN of thrust, ISP ~1,000,000 seconds).
It can channel part of the engine's radiation through the hull and spine via bremsstrahlung and fire it as a powerful gamma-ray laser.[/hider]
[img]http://i.imgur.com/n7Es4Lv.png[/img]
[hider=Adaptive Armor][i]Babel's[/i] hull is coated in meters of ferrous material that changes thermal properties radically with electrical current, acting as a form of adaptive armor.  It can act as both a thermal insulator or a thermal conductor, serving as both ablative and conductive armor.[/hider]
Along it's spine is a powerful radiator array, which combined with the adaptive armor is sufficient to allow [i]Babel[/i] to enter a star's photosphere during a Sundive.
Babel carries dozens of smaller support craft, most around 20 meters in length.  Tugs, atmospheric and non-atmospheric landing craft, mining ships and boarding drones.
[/hider]