If you ever get a glimpse of a newly hatched butterfly, you will notice their first line of business is to get their proboscis up and running.
When butterflies emerge, their proboscis is split into two and they must curl it in and out to zip it together. The proboscis is like a tongue and is what they use to slurp up nectar. The butterfly will not survive if it’s born with a faulty proboscis. When not in use, it is coiled tightly against the head and uncurled during feeding. The proboscis looks like a straw but it actually functions more like a paper towel with tiny grooves that draw liquid upward along the edges, carrying along the bead of liquid in the middle the tube.