The left half of the Ark's main corridor, the Bridge is the command center of Creatures 3 - from it you can view a map of the Ark (and the locations of creatures within!), and the monitors for the four cameras spread through the terrariums of the Ark. The Bridge also contains a Knowledge Stone and emergency rations in the form of a Cheese Machine.
Even further below is the larger of the two Airlocks - Beware! If an unsuspecting creature wanders in and happens to push the activation button, they'll be launched into cold space in a matter of seconds. However, the airlock does provide a convenient means to destroy agents that don't fit in the Recycler. Or the occasional grendel.