Octopuses and Squids: Amazing and Strange Animals

From "How Octopuses and Squids Change Color"

Squids, octopuses, and cuttlefishes are among the few animals in the world that can change the color of their skin very fast. These cephalopods—a group of mollusks (mollusks are animals like octopuses, oysters, and snails) with arms attached to their heads—can change their skin tone (color, darkness and lightness) to match their surroundings, making them nearly invisible, or give themselves a pattern that makes them easily seen.

Camouflage is the way in which some animals are colored and shaped so that they cannot easily be seen in their natural surroundings.

Many thousands of color-changing cells called chromatophores just below the surface of the skin are responsible for these amazing changes. The center of each chromatophore contains an elastic sac full of pigment (color), rather like a tiny balloon, which may be colored black, brown, orange, red or yellow. If you stretched a dye-filled balloon, the color would gather in one spot, stretching out the surface and making the color appear brighter—and this is the same way chromatophores work. Nerves and muscles control whether the sac is expanded or contracted and, when the sac expands, the color is more visible. 

Besides chromatophores, some cephalopods also have iridophores and leucophores. Iridophores have stacks of reflecting plates that create iridescent (shiny like metal) greens, blues, silvers and golds, while leucophores mirror back the colors of the environment (what is around the animal - rocks, sand, etc.), making the animal less conspicuous (less easily seen).

The most obvious reason such a soft-bodied animal (an animal without bones) would change color is to hide from predators (animals that will eat it)—and octopuses are very good at this. They can change not only their coloring, but also the texture of their skin to match rocks, corals and other items nearby. They do this by controlling the size of projections (bumps) on their skin, creating textures ranging from small bumps to tall spikes. The result is a disguise that makes them nearly invisible. 

An camouflaged octopus becomes visible suddenly and squirts ink as it swims quickly away

Color changing is just one of an octopus’s defenses, however; it can also spray ink (watch the video above), and make a quick escape through any hole it can get its hidden bony beak through (octopuses have beaks like birds such as parrots).

Intelligence is another way an octopus can defend itself. We'll look at how smart octopuses are in another blog post. This short video will give you an idea of how smart they are. - Derek

Mollusks or Molluscs are a group of soft-bodied invertebrates distributed across ocean, freshwater, and land habitats.