SEM Micrographs of our Spider, Mosquito and Morpho Butterfly "Volunteers for Science"
 

Observations and speculations from a class of NON-insect experts (because we ARE scientists and can try to figure things for ourselves!):

SPIDER

 
Appearances to the contrary, the spider is really only about 1mm end to end  

At their flexible joints, suits of armor employ small protective flaps. Is this a similar flap protecting the spider's waist?

 

 
But the elbows (leg joints) do not seem to have protective plates. Instead the gaps are filled with small regions of flexible tissue (just as you see at a crab's leg joints).  

Are these breathing holes all over the back of the spider's abdomen? And are the corrugations in the shell to allow the abdomen to expand and contract?

 

 

Three of the spider's eyes (after drying out for almost a year). At very high magnification the surfaces appeared surprisingly rough. But this roughness was smaller than the wavelength of light (~ 0.3 to 0.6 microns) so light would not be scattered by this roughness.

 

  Spider touch sensor - a hair carefully positioned in the center of an open follicle?
 
One of the spider's toes showing two opposing combs that we speculate grasp a filament of spider web silk.  

ALL of the surfaces near the spider's toe had very fine ribbed surfaces. Is this a way of minimizing the contact area with the web filament and thereby reducing sticking due to Van der Waals forces?

 

 

The spider's rear end showing what we assume are the spinnerets plus the small arms used to pull out the silk.

 

  The liquid silk "dispensers" themselves - employing surface tension to suck the liquid silk up into their partially hollow cores?

 

MOSQUITO

 

The mosquito's eye. Are the fine hairs between each and every lens protection against parasites? Or, by holding droplets away from the surface, do they help the mosquito to shed water?

 

 

The end of the mosquito's blood sucking proboscis (it had broken off so we were unsure)?

 

 

The incredibly complex shoulder joint of the mosquito (the wing extends out towards the lower left).

 

 

The shoulder joint seen more closely (viewpoint rotated 90 degrees CW from one at left).

 

 

Mosquito nose: Fine texture of antenna-like structure above eye. Note the thousands of nanometer scale holes.

 

  This was just forward of the mosquito's shoulder/wing joint. An ear? A breathing portal? Something else?
 

The surface of the mosquito's wing, which like all other surfaces was covered by fine hairs. Again, are they parasite or water repellers? Or might they play a role in setting up an aerodynamic boundary layer helping the wings to beat faster?

 

Mosquito knee.

   
Hairs on the mosquito's abdomen    

 

MORPHO BUTTERFLY WING

 

We had read about many nanoscience researchers taking interest in the wings of the morpho butterfly. But the articles were frustratingly vague about WHY they were interested! We suspected it might have something to do with the strange shimmering blue color of these wings. The changes in color with angle suggested a diffraction grating like surface structure. Then Luke came up with a specimen. At low magnification the wing appeared to be covered by petal like structures.

 

When we increased the magnification of the "petals," we began to notice stripes in their texture.

 

 
At higher magnification the stripes were composed of rows of rectangular shapes.  

Which at even higher imagination seemed to consist of a rectangular lattice suspended above the solid surface of the wing.

 

 

On different "petals" the square cells had different widths. Petal to petal, the widths varied from about 1.5 microns down to 350 nanometers (as in the one above). This would correspond to light wavelengths from the infrared to ultraviolet. But on most petals, cell widths had sizes corresponding to visible light wavelengths (i.e., 400-600 nanometers), and the most common widths were about 400 nm (the size of blue light). This makes sense as we perceive these wings as having a shimmering royal blue color.

 

Here you can see the incredible nanostructure of these "petals." On their surfaces they appear to have lattices suspended atop pillars, with the finest features or the lattices well under 100 nm in width.

The sizes and regularity of these rectangular lattices supports the idea that with these "petals" the morpheus butterfly is indeed using diffraction gratings to direct specific reflected colors into specific directions.

But what evolutionary purpose could this use of diffracted light serve?

Well, when we zoomed back out, we noticed that each petal was attached to the underlying wing surface via a single "stem" and socket. Could this arrangement have allowed the butterfly deliberately twist the "petals?" If so, the diffracted light beams would then be swept in different directions.

This might produce a strange shimmering light pattern that could mimic the way squids use chromophore-based colors to flash confusing patterns at pursuing predators (or, of course, it could just be a peacock like way of attracting mates).