Friday, December 18, 2009

Animal to Machine

Chromatophores are often used for camouflage. This picture (courtesy of the Field Museum of Natural History) shows a winter flounder resting on a checkerboard pattern.

The chromatophores of cephalopods change size (expand and contract) as a result of activity of muscle fibers and the motor neurons that terminate at them. In crustaceans and amphibians, the chromatophores have a fixed shape. Color change comes about through the dispersal (darkening) or aggregation (lightening) of granules within the cell. This is under hormonal control.

Saturday, March 28, 2009

Friday, March 27, 2009