One find particularly prized by divers is that of the octopus because it is a master of deception. At first, the octopus's wealth of disguises seem like overkill for an animal equipped with eight arms, a sharp beak, venom and a big brain (researchers put their smarts at the top of the invertebrate heap, comparing their intelligence to that of a house cat). In actuality, having a soft body and no protective shell on its back makes this mollusk a tempting target for various fish and mammals. When desperate times call for desperate measures, the octopus changes skin color and texture to identically match the background. The tools used for this transformation are chromatophores (literally, colored bodies), sacs of yellow, red, brown and black pigments that cover the body's dermal layer like a rash of hives. Unlike an allergic reaction though, the cephalopod controls which of the pigment spots to expand and contract to achieve the desired colors and pattern. What's more, a selection of skin textures, such as smooth, pebbly or spiky, are available to achieve an optimal match to background.
Life being imperfect, the octopus's cover is still sometimes blown, requiring it to simply flee from a predator. Using a form of locomotion, jet propulsion, (not devised at Cal Tech), the animal employs its funnel to which jets of water are passed. The result is a speedy, yet backwards, exit. For an extra measure of security, the cephalopod may squirt a cloud of dense, dark ink, which it synthesizes and stores for just such emergencies. The few seconds that it takes until the smoke clears and the predator realizes it's been duped is typically all that's needed for the octopus to escape. I can further attest that the ink ejected is not just any blob but a doppelganger of the real deal. How it does this is a mystery. I wonder that the predator is as flummoxed by the decoy octopus as I am amazed by the sleight of ink.
The chromatophores may also take on the opposite function, that of promoting visibility. Time when an octopus doesn't want to be invisible include when taking an aggressive stance or in social situations, like wooing a mate. Here, the octopus dons color, pattern, and textural skin changes that make for an eye-popping splash. Whether it's to hide or display, it takes a fraction of a second (like blushing) to bring out yellow, brown, white, pink, or a variety of mottled colors.
Highlights Hidden Pictures are now also online but this version has a twist. When players find an object, which is camouflaged in the monochromatic picture, they tap it with the computer mouse, and it turns to color. So we are once again in synch because in my underwater version, the camera's flash does the same, separating the octopus from its otherwise background camouflage. Play my interpretation, and see if you can find the octopi in the pictures posted here. Some are easy, some not so much. For the later, first look for the eyes (black slits), then find the rest.
— Judith Lea Garfield, naturalist and underwater photographer, has authored two natural history books about the underwater park off La Jolla Cove and La Jolla Shores. Send comments to firstname.lastname@example.org.