Recent news that the population of octopuses in the world's oceans has increased significantly for the past 50 years sparked my curiosity about these unusual creatures.  For example I didn't know that they possess unusual motor skills and intelligence.  Further research indicated that a number of books have been written about them and other cephalopods.  I learned that octopuses (not octopi) and humans have a common ancestor, possibly a slug like organism, that lived more than 550 million years ago, and that the octopus has evolved a camera eye closely similar to ours, but radically more elegant in design.  The ancient Greeks christened the animal oktopus, which means, unimaginatively  and inaccurately, "eight foot."   The correct label for the appendages is actually "arms."  This and other brief facts, e.g.,  why octopuses don't tie themselves in knots,  will be included in this article and intended for curious individuals  with an interest in surgery, evolution and zoology.

Octopuses belong to the class Cephalopods, an ancient group of invertebrates (animals that lack a spinal column)  that appeared in the late Cambrian period several million years before the first primitive fish began swimming in the ocean.   All cephalopods inhabit marine environments, none are found in fresh water.  All are strictly carnivorous, and most hunt for prey.  They generally grow quickly and have a short life span.   As a consequence they do not have a chance to pass on what they learn to the next generation.

Cephalopods have gangly limbs encircling their mouths, the octopus possesses cone-shaped limbs (arms) with rows of suckers or suction cups.  An octopus, like other cephalopods, has three hearts, two pump blood to the gills, and one central heart pumps oxygenated blood to the body.  Like other cephalopods, octopus blood is blue because it binds oxygen using a blue, copper containing protein called hemocyanin.  (Human blood is red because the oxygen binding protein hemoglobin contains iron.)

The hundreds of highly sensitive suction cups and the prehensile (capable of grasping or seizing) arms of an octopus are as effective in holding and manipulating objects as the human hand.   The cups will stick to just about  everything, with one important exception.  They will not grab onto the octopus itself, otherwise the animal would find itself entangled and helpless.  Researchers observed the behavior of amputated octopus arms, which remain very active for up to an hour after separation.  Those observations showed that the arms never grabbed octopus skin, though they would attach to a skinned  octopus arm.  Apparently a chemical produced by octopus skin temporarily prevents their suckers from adhering.  According to the report, the results show for the first time that the skin of the octopus prevents octopus arms from attaching to each other or to themselves in a reflexive manner.  The octopus, surprisingly, can vary the stiffness of its arms, temporarily transforming the flexible limbs into stiffened segments to allow the octopus to move and interact with objects.

Cephalopods may have brain cells similar to humans and some species have been used to study how our brains work.  If similarities are found, it would significantly alter the perspective on the emergence of life elsewhere in the universe. 

Octopuses are considered by many to be the most intelligent of invertebrates, they have highest brain-to-body mass ratios.   In addition, they have the manipulative ability to get into fishermen's crab traps, eat the crabs, and escape.  They can solve simple mazes, open childproof bottles, build dens and can dismantle the aquariums they are kept in and can grow a new arm when one is bitten off.   Once the arm is regrown it is basically as good as new.  Octopuses have been known to  throw rocks and smash aquarium glass, and on occasion to cause short circuits by crawling out of the tank and shooting a jet of water at an overhead lamp.  Octopus dexterity is a marvel. 

Octopuses are among the few animals in the world that can change color, matching it with their surroundings, rendering them nearly invisible, or alternatively give themselves a pattern that makes them stand out.  Many thousands of  color- changing cells called chromatophores just below the surface of the skin are responsible for these remarkable transformations.  The most obvious reason to change color is to hide from predators.  An octopus can change not only its coloring, but also the texture of its skin to match rocks, corals and other items nearby. 

Throughout the years scientists have gained greater insight about the intelligence of the octopus.   Recently, the octopus has become a new scientific model for researchers looking to study tissue regeneration.  Findings could enhance progress in the Holy Grail of modern biology and create a storehouse of repair parts for the body.  Octopuses  are utterly different from all other animals, even ones they are related to. Moreover, they have somehow gained seemingly extraterrestrial capabilities and represent the pinnacle of an evolutionary track alternate to man and there is still much to learn from these marvelous creatures.

Max Sherman is a medical writer and pharmacist retired from the medical device industry. He has taught college courses on regulatory and compliance issues at Ivy Tech, Grace College and Butler University. Sherman has an unquenchable thirst for knowledge on all levels.  Eclectic Science, the title of his column,  will touch on famed doctors and scientists, human senses, aging,  various diseases, and little-known facts about many species, including their contributions to scientific research. He can be reached by email at  [email protected].