So I am using Unity 5.5.1 and I noticed that when using OnTriggerEnter2D for the shredder I was unable to get a response from the script, but when I switched to the OnCollisionEnter2D the shredder script worked just fine.
I was wondering if there is any reason to use OnTriggerEnter2D specifically and would love any insight on why one might work as opposed to the other.
EDIT:
I had not made the appropriate colliders triggers.