Updated on 2018-01-13: They probably don’t know about stuff like “infrared” or “different wavelengths”, so that’s how they explain creatures that can see in the dark.

↓ Transcript
Shara: Hey, Kshar, have I told you how she nearly got eaten by a dragon leaper? That was HILARIOUS!
Katharina: W-would you shut up?! That wasn't funny!
Kshar: <amused> Tell.
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Shara: Well, we startled that thing and she was all like "OH NO OH GOD SHOOT IT KILL IT HELP" and I just backed up 'cause she got all of it's attention through her BEGGING and WHINING ...
<Katharina facepalms>
Kshar: Heh, yeah. Those beasts rely mostly on sound and their darkvision.
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Shara: "Darkvision"?
Kshar: Yes, their eyes amplify every bit of light. A small torch is like a sunrise for them.
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<Shara bursts out laughing>
Shara: BWAAHAHAHA! FUCK! You heard that, princess?! Your magic light shit must've nearly blinded it!
Katharina: Hrmf.
Shara: No wonder it tried to rip you apart!