[Sekto Springs]

Scrabs: use echolocation, aswell as teriffic hearing when they hear something or detect something other than a scrab they roar sending signals to the others. notice how in MO when you walk close enough to a scrab herd to hear you, they all turn and face you, it's like "hey i heard something right there"

Paramites: most likely sense vibrations being so close to the ground like Max stated, but also someone had said the beleived they saw parmite eyes in the gamespeak CG model.