Clear as glass

[beautifulduckweed]

Thanks to today's Cute Overload, I've learned that glasswing butterflies exist.

They're gorgeous, but mostly, I'm fascinated by translucent animals. I've seen it in marine animals--various species of cephalopods, cnidarids and crustaceans are in possession of clear tissues; this is, however, the first time I've noticed a terrestrial animal with that trait.

What I wonder is: what is the mechanism that makes those tissues clear? I understand (on a very basic level) how color perception works in humans, and why something appears to be a particular color, but the thought of being able to evolve a tissue so that lightwaves pass through it instead of being absorbed or scattered breaks my brain a little bit. It strikes me that it'd be much easier to pull off in a marine environment, for some reason--I have some vague (and utterly crackpot) theories regarding water and the water content of marine invertebrates. Any of you biologist types in the audience want to take a crack at explaining this to a layperson? Or point me to some helpful resources that could help explain it?

Comments

[rat-bastird.livejournal.com]

eye lenses. Gelatin. insect wings (flies, bees, dragonfly)

Not an answer but something to think about.

It's a good question. I figured they just raided the saran wrap company.

[misshepeshu.livejournal.com]

eye lenses. Gelatin. insect wings (flies, bees, dragonfly)

Oh, yeah, well, duh. Heh. Don't know where my brain was. I had completely forgotten about dragonfly wings and eye lenses. Boy, do I feel dumb.

Still interested in how translucency works, though.

[rat-bastird.livejournal.com]

yeah, and i liked how they were framed :)

Doesn't make your question dumb though... i'm curious too now! I actually feel dumb because I've never even thought to ask or wonder about it.

[misshepeshu.livejournal.com]

An interesting issue with translucency, especially for us mostly-opaque-except-for-a-few-clear-bits vertebrate beasts, is keeping the tissues nourished and in good shape while not occluding it with things that aren't translucent, like blood. Of especial concern is getting oxygen to those bits. Parts of us, like the cornea, get the oxygen directly from the air and not from blood vessels, which is why if you deny your corneas oxygen for too long (as with inappropriate soft contact lens use), corneal neovascularization results--the eye grows blood vessels and transmit oxygen to the cornea that way to compensate for the lack of oxygen it's receiving from the air.

Beasties that are translucent through and through must have clear blood, and that really interests me. Do they actually have blood at all, or are they small enough that they, like some insects, are able to absorb the oxygen directly from the atmosphere (well, water in their case) and forgo the complications of having carrier molecules for the oxygen? Etc.

I have nothing of substance to contribute to the issue, so...

[darwinpolice.livejournal.com]

BUTTSEX.

Re: I have nothing of substance to contribute to the issue, so...

[misshepeshu.livejournal.com]