avp - Can Aliens see cloaked predators?

Although Xenomorphs don't have visibly obvious eyes, they have been demonstrated to be capable of seeing. For example, in the Aliens 3 movie, the runner has fish-eye vision similar to human. In the AVP PC games, aliens have two visual modes, one similar to human vision and another short-range sonar like vision that can be used to navigate in the dark.

Xenomorphs certainly can sense, if not see, cloaked predators. In the movie AVP 1, a Xenomorph drone impales a cloaked predator with its tail. Granted, the cloaked predator was moving, its cloak wasn't as effective as it was in a well lit area, and it made a sound by activating its wrist blades, but the drone had no problem knowing exactly where it was.

In the AVP PC games, Xenomorph see an aura around different species even cloaked predators. However, this aura is probably meant to convey a sense of smell as well as the sense of a slight bioelectric charge around living things like Matt said above with the shark example.

The entire skin of the Xenomorph is covered in ions which lets the Xenomorph use its entire surface area as a sophisticated EM sensor and nose. This is why in the AVP PC games Xenomorph appear to have electric fields around them when viewed by Predators in EM vision. This is also why Xenomorph are stunned by EM grenades whereas humans are not. The EM burst overloads the Xenomorph's sensory system like a flash-bang grenade would do to a human.

In any case, the Predator's cloaking device is worthless against xenomorphs and is best turned off so as not to drain energy from the Predator's weapon systems while fighting only Xenomorphs. Fighting both humans and Xenomorphs can be tricky for a Predator because the two prey are best dealt with using completely different tactics.