predators, eat meat, but people saying they tear the meat with their teeth...as if they just bite into it like some kind of wild animal...please they sivial creatures, and far more advantage than us.they have their
wristblades.im sure they use them to cut the meat into small pieces to eat.and by the looks of the mouth in predator and AvP it looks like they take small bites,smaller than what humans eat at a time
as for the aliens
they take the energy they need from the enviroment.but from the chestburster to adulthood. they would eat meat.small
animals.bugs.cats.so on and so forth.and at adulthood. they would knock people out...even if it does look like they kill them with the head bite.take them back to the hive...or a area that they have changed to their own(eg in alien on and alien 3.there was only one alien,im sure they both had areas they would go by themselves) concoe(i cant spell
then later eat if they need
they would use their secondary mouth to eat,just has they use it to attack
taken small mouth bites and swallowing
hope that helped abit