Did you know the Glass Squid genus (Cranchiidae) ranges in size from under 4 inches to almost 10 feet? This unique family of squid have several species of smaller transparent squid and their cousin the Colossal Squid, which is much larger than the more commonly known giant one.
The transparent Glass Squid live in shallower sunlit water and try hard to minimize the silhouette they show against the sky. The only parts of their bodies that aren’t transparent are their eyes and the digestive organs. To account for this many have bioluminescent organs under their eyes to hide them from predators below. To reduce the shadow cast by their digestive organs they hold them in a vertical position even as their body changed angle. So whatever direction they’re pointing they minimize the silhouette made by their organs and their meal. That’s not a concern for their 1000lbs Colossal cousins who live in deep Antarctic waters. They aren’t transparent, their biggest predators are Sperm Whales who hunt with sonar.
colossal squid also camouflage, they are generally red or pink in color, and this color helps to hide them. In the deep ocean the longer wavelength (reds) light has been filtered out by the thousands of feet of water above, however shorter wavelength (blues) light can penetrate much deeper. This means at depth there is no long wavelength light, and since there is no red light, it can not reflect off anything that is colored red, making the squid virtually disappear! Also because red light does not exist at depth, many animals have evolved to be unable to see red at all.
At the bottom of the ocean red skin is just as good as clear skin.
David Ishee
 ){kind=link}
0 Comments