Cephalopod Defenses by Ellen Prager
To avoid the ocean’s hungry masses, cephalopods have developed an extraordinary array of defenses. When confronted, a cephalopod’s first line of defense is camouflage, perfectly matching the brightness, color, pattern, and texture of the seafloor in seconds, create optical illusions, and change the shape of their bodies to mimic in 3-D. Scattered throughout a cephalopod’s skin are thousands of small color organs called chromatophores, essentially little elastic sacs containing pigment. When muscular contractions stretch these sacs, a cephalopod’s skin becomes colored or patterned. Surprisingly, their chromatophores contain only red, orange, yellow, black, or brown pigments, yet cephalopods exhibit a full range of colors.
As true masters of disguise, octopuses and cuttlefishes can also change the texture of their skin, creating ridges, bumps, or algae-like frills. Even the iconic chameleons cannot match their speed or capabilities as quick-change artists. Some cephalopods also have an illuminating means of camouflage. Squids can produce light that matches the radiance downwelling from above thanks to photophores. This counter-illumination makes them invisible to predators looking up from below.
If camouflage fails, the cephalopods have several other tricks up their suckered arms. They may attempt to startle a predator with flashing color, a rapidly changing pattern, or the release of ink. This smokescreens creates a quick escape or as more of a decoy when released in combination with mucus. Cephalopod ink may irritate the eyes of the attackers, and cause disorientation.
If camouflage or counter-measures don’t do the trick, cephalopods can exhibit erratic behavior in hopes of confusing predators. And if none of these tactics work and a hunter successfully grabs an appendage, cephalopods are able to regenerate lost arms. Some can even lose a limb on command.
Photo credits: Ernst Haeckel
