Headcrabs!

[Angrist]

How do you know the host bodies are still alive and conscious after their mutation?

Which race do you think stole the other race's idea? The combine with their head crabs, or the Aliens with their face huggers?





vs

[Combine 017]

Originally Posted by Angrist

How do you know the host bodies are still alive and conscious after their mutation?

I think they said it in the game, and if they didn't then because I'm a nerd and looked it up.

Which race do you think stole the other race's idea? The combine with their head crabs, or the Aliens with their face huggers?

They are a different kind of parasite. A face hugger jumps on the host to plant an egg, then falls off and dies. A headcrab jumps on the host and stays there, receiving nutrients from the host body.
Also, headcrabs don't belong to The Combine, they are just on a planet that The Combine have conquered.
And the last pic there is pretty awesome.