Here's another of Casey Dunn's Creature Casts, this time on shifting color spots in marine snails.
Pigment cells are always very, very cool. I've been intrigued by them for a long time — they show up in my time-lapse recordings of developing zebrafish and are always active. Here's a quick one, a few hours of time in a roughly 24 hour old zebrafish embryo, compressed to about 30 seconds. You can see one corner of the dark eye at the bottom left of the image, and that oval structure near the middle with two spots in it is the ear and its otoliths. The melanocytes are writhing over the side of the head and down onto the yolk sac; they're not quite as colorful as the snail, but then, the zebrafish is a mostly black and white animal.
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Forgive me, but I'll inflict a few more zebrafish videos on you. YouTube makes this fun and easy, and I'm going to be giving my students instruction in video micrography next week, so it's good practice.
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You mean that pigment cells don't arrange themselves like party balloons?
I always like the IDiots saying that we didn't evolve from amoebas. Which, of course, we didn't, but we clearly have cells that share amoeba-like actions. These remind me of others that fit the bill better, B cells.
It's just a chance whim of the designer, though, that we're akin to all other life on earth.
Glen D
http://tinyurl.com/mxaa3p
Thanks for both videos, PZ. They're both interesting.
Is that the soundtrack to Dark Star in there? If so, brilliant use of close-ups to match the opening of the movie. Can't find a youtube clip to confirm, tho.
Melanocytes are neural crest derivatives, yes?
"A new head and spots," then.
The zebrafish melanocytes are wicked.
Zebrafish,Sprebrafish ! What about the Zebra ?
White on black or black on white stripes? Melanocytes in the white skin or not?
:-)