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A Cloak of Near Invisibility in an Underwater World
For many animals, being noticed can mean being eaten or scaring away a would-be meal. From the tiger’s stripes to the snowy owl’s downy white feathers, camouflage allows animals to hide in plain sight and avoid these perils. But camouflage is often about more than color. Some animals have skin texture that matches the texture of their environment. Other animals have shapes that make it hard to spot the outlines of their bodies.
Camouflage that matches one environment may stand out in another environment. This can be a big problem for animals that need to remain mobile. Cuttlefish, relatives of squid and octopi, handle this in an extraordinary way. They have changeable camouflage that adapts to new surroundings in a split second.
Cuttlefish change the color of their skin by covering or exposing many tiny colored spots, called chromatophores. These spots expand when the small muscles around them contract. Together, exposed chromatophores can create solid colors or complex patterns across the whole surface of the animal. Sometimes these patterns are mottled, resembling variation in the background colors. At other times the patterns don’t match the environment, but instead have high contrast with distinct edges. It might seem that these jarring patterns would stand out, but instead the false edges disrupt the outline of the body and mask its overall cuttlefish shape. This is the same strategy that led to dazzle camouflage, the bold patterns painted on ships to hide them at sea.
But the exquisite camouflage of cuttlefish is not limited to their color changes. They can also alter the texture of their skin. This is done with small organs called papillae. There are many papillae scattered across the skin. In their relaxed state, they are flat. Papillae have multiple muscle groups. When the circular muscles that ring the base of a papilla are contracted, the skin bunches up and the entire structure extends out. Other muscles control the shape of the extruded papillae, fine-tuning their texture. Those texture changes occur at the same time as the shifts in color brought about by the chromatophores, but little is understood about how these processes are controlled.
What is even more astounding is this master of camouflage can tune its own colors so precisely, yet it is completely colorblind.
This episode of CreatureCast about Cuttlefish camouflage was made by Jacob Gindi, a student in my Invertebrate Zoology Course at Brown University. The music is by Akajules. Cuttlefish also use their dynamic colors for communication, as explained in a previous episode of CreatureCast. You can find even more CreatureCast episodes here.
Explore the Animal Kingdom
A selection of quirky, intriguing and surprising discoveries about animal life.
Scientists never imagined that the blind cave salamanders called olms willingly left their caves. Then, they discovered several at aboveground springs in northern Italy.
According to a common narrative that male mammals tend to be larger than female ones. A new study paints a more complex picture.
Daddy longlegs, the group of splendidly leggy arachnids also known as harvestmen, have been thought to have just two eyes. New research has uncovered four more vestigial ones.
The means by which some whales sing underwater has long been a mystery. A contraption that forced air through the larynxes of three carcasses puts forth an explanation.
Here’s how a male elephant seal, not usually possessed with a paternal instinct, prevented a younger animal from drowning in an unlikely act of altruism.
What paleontologists long believed were long spines on the aptly named Alienacanthus, an ancient fish, turned out to be an extended lower jaw.
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