What Butterflies Have in Common with Straws
by Paige Brown, Museum Blogger-in-Residence.
If you guessed ‘their proboscis” for what butterflies have in common with straws, you are right! The butterfly proboscis is a slender, tubular feeding structure that works like a straw through which a butterfly drinks its food. When the butterfly first emerges from its pupa or chrysalis, its proboscis is actually in two parts that are later brought together and fused to create a structure that is hollow on the inside, like a straw.
The butterfly’s proboscis is made up of muscles, nerves (for the butterfly to feel things with), and breathing organs. When the two parts of the proboscis in the young butterfly are fused or “zippered” together, a hollow channel remains open on the inside. It is through this hole, like a straw, that the butterfly sucks up liquids and small particles extracted from flowers, for example.
And, somewhat similar to a very small straw, liquid is brought up into the butterfly’s proboscis by capillary action. Capillary action is a process by which water can flow through very small channels on its own, even against the force of gravity, thanks to the “sticking” force between water molecules caused by hydrogen bonding.
When the butterfly isn’t feeding, its proboscis is kept curled up near to its body, as shown in the picture above. But when the butterfly is feeding, it extends its proboscis through hydrostatic pressure (pressure produced by balancing fluids across a membrane) in order to sip nectar from flowers, as shown in the picture below.
How cool! Engineering at work for biology! Next time you sip sweet juice through a tiny straw, think of butterflies!
Want to see these butterflies in real life? Visit the North Carolina Museum of Natural Sciences’ Living Conservatory on the 4th floor of the Museum’s main building!