When a Shark Invader has a blue glow, it mostly fleas away from your Shark and does not attack your Shark. Sharks that are higher tier and the same tier as your shark will attack you, while lower tiers will swim away or (maybe) sometimes will attack you if you swim to close to the Shark Invader.
After the Halloween update of 2020, they seemed to have gotten a lot tougher than they used to be, as you have to bite at them for a long time before you eat them (taking time to eat a type of prey wasn't seen at all in HSE before this update).
Other than that, their looks and damage vary. They always have red lights on their head with two metal tongs and a flow of electricity going through them.
