Mutated Spidies are just like the normal Spidy. They will walk around in a unpredictable pattern and try to eat you. The difference is that Mutated Spidies are much faster, take less knockback, have more health, and deal more damage. They can also summon regular Spidys to help attack you. They are like a Mini Boss.
Mutated Spidies will attack by walking toward the player trying to bite. When hit they will slow, stop or sometimes keep coming. This makes it hard to predict what they are going to do next.
On death Mutated Spidies do not drop anything.