|Cause of Death||N/A|
|Abilities||Long sharp barbed tongue|
Rat Species is a regular rat who got assimilated with the Unnamed Alien Species DNA.
A regular rat dragged away one of Sil's nipple tentacles that got cut off in the fight between Sil and Preston Lennox. It's unknown how the rat got assimilated with the alien DNA. After the changes started, the rat used its newly-gained long, sharp and barbed tongue to kill and eat another rat.
Events in the comics happened as they did in the film, but Species Rat was shown after it had consumed another rat in its full alien form.