Giga Siren is the odd one out in it's evolution line; it doesn't really know where it falls. It looks kinda like a catfish, too.
Giga Siren can deal pretty basic damage and seems to bully Magnamods specifically. All of it's attacks ignore ARM, or at least, against slow Magnamods they do.
Also, Giga Siren 1.0 can weaken incoming damage by using Sonic Strike and Siren Sphere, which both lower the opponent's STR and have their own secondary effect.
This Nanovor is fully evolved and cannot evolve further.