The Ark Class ship formed part of the three-fold survival plan of the wealthy and powerful of the Petroleum Age. The other two legs of the plan were the arcologies, and space habitats.
Urbants-Creatures that move quickly around on their massive arms, and their "legs" dangle about from their torso, at about elbow length. They can move fairly quickly, but not as fast as an obese human, and can "jump" fairly high. Their "legs" are very powerful, and can kill with one blow. The bad thing is, Urbants cannot block attacks at their heads, which have relatively no neck, from the length of their legs being so short.