The Incredible Proboscis

Proboscis in two halves

In the last blog we mentioned that when butterflies emerge from the chrysalis, their proboscises consist of two C-shaped fibers called galeae, which are then united, sealing the halves into a flexible elliptical tube.  So how do the two halves come together to form the functioning tube?  Self-assembly of the Butterfly Proboscis from Clemson describes the process which includes the butterflies' saliva and capillary forces.

No muscle action is required to hold the parts together.  Asknature.org has  technical descriptions of the linkage mechanisms.  This linkage also allows the proboscis to remained coiled without the use of muscle, reducing its energy requirements.

So once the two galeae are sealed together, is that a permanent bond?  I can recall a grade school bully who used to pull the wings off of a butterfly.  In a more scientific version, Suellen Floyd Pometto and colleagues separated the two halves of the proboscis in the name of science.  She performed this on monarch (Danaus plexippus) and painted lady (Vanessa cardui) butterflies, then studied the repair process.  Both species were able to accomplish repair of the proboscis, with variable rates of success.  Those achieving reunion of the galeae had recovery of the coiled resting state and dye studies then confirmed that the restored proboscises functioned normally.

Convolvulus hawk-moth_(Agrius_convolvuli)

That same paper also provides an in depth look into lepidoptera feeding strategies as well as the functions and mechanisms of the proboscis.  It also provides a listing of the 19 different muscles that control the proboscis in slurping up fluids.  The lepidopteran proboscis is a versatile tool to obtain different sources of minerals and food.  Some species are even able to pierce fruit and mammalian skin as discussed in the next blog.