Seems that some squid can hide messages in their skin:
In the animal world, squid are masters of disguise. Pigmented skin cells enable them to camouflage themselves—almost instantaneously—from predators. Squid also produce polarized skin patterns by regulating the iridescence of their skin, possibly creating a “hidden communication channel” visible only to animals that are sensitive to polarized light.
[...]
Mäthger and Hanlon’s findings present the first anatomical evidence for a “hidden communication channel” that can remain masked by typical camouflage patterns.
blog entry/links/comments: http://www.schneier.com/blog/archives/2006/09/steganographic.html>
Posted by Stubbornson at September 30, 2006 07:26 AM