Patient and mostly passive creatures that are known for their incredibly powerful sense of hearing, the Listening Risuna most commonly wait patiently for warm-blooded mammals to fall asleep and gently and painlessly sips their blood as they sleep. While their retractable straw-like mouths are small enough to fit in between nerves to prevent the prey from noticing, they find the perfect place to inject it by listening to the blood flow inside of the capillaries and the sounds it makes resonating off the nerve endings to avoid detection. It is also believed they can hear when their meal's blood flow slows down from their heart rate decreasing in the first and second stages of light and deep sleep. They risk being detected if they feed during the REM sleep cycle, as it is common for dreams to cause mammals to kick or move in their sleep, potentially blowing its cover.