Slitherine

Regarding the theoshans, do they have a tech tree and get progressively better ships? The reason I ask is because in my playthrough, I've had battles against a handful of theoshan battleships and escort cruisers and destroyers. In the first of these encounters my ships completely wiped out these attackers without losing a single ship, and this is without the advanced weapons that are supposed to make it easier to kill them but then over time, those same fleets with pretty much the exact same compositions attacked again and completely wiped out some of my smaller fleets which had 40-50 ships in them. I dont understand how this would be able to happen without the theoshans being able to upgrade their stuff.