TENTACLE: MUSCULAR HYDROSTAT

Japanese creators of explicit artwork were at some point forbidden to depict penile penetration.  Given their close association to octopi and squid (eating them), they simply substituted tentacles, giving rise to a genre of pornography called “tentacle” porn.  The idea turned out to be a sci-fi-ish bonanza mixing monsters with sex.  I came to this subject because of a fine article about the physiology of octopi called “The Footed Void,” but then I looked up the physiology of tentacles.  Most of us get to the gripping suckers and that’s enough -- PLENTY, in fact,  But there’s more.  Tentacles are muscular hydrostats.

A muscular hydrostat is a biological structure found in animals. It is used to manipulate items (including food) or to move its host about and consists mainly of muscles with no skeletal support. It performs its hydraulic movement without fluid in a separate compartment, as in a hydrostatic skeleton.

A muscular hydrostat, like a hydrostatic skeleton, relies on the fact that water is effectively incompressible at physiological pressures. In contrast to a hydrostatic skeleton, where muscle surrounds a fluid-filled cavity, a muscular hydrostat is composed mainly of muscle tissue. Since muscle tissue itself is mainly made of water and is also effectively incompressible, similar principles apply.

In a muscular hydrostat, the musculature itself both creates movement and provides skeletal support for that movement. It can provide this support because it is composed primarily of an incompressible “liquid" and is thus constant in volume. The most important biomechanical feature of a muscular hydrostat is its constant volume. Muscle is composed primarily of an aqueous liquid that is essentially incompressible at physiological pressures. In a muscular hydrostat or any other structure of constant volume, a decrease in one dimension will cause a compensatory increase in at least one other dimension.The mechanisms of elongation, bending and torsion in muscular hydrostats all depend on constancy of volume to effect shape changes in the absence of stiff skeletal attachments.

Consider some examples in other animals.  

• Whole bodies of many worms 
• Feet of mollusks  (including arms and tentacles of cephalopods (octopuses and squids) 
• Tongues of mammals and reptiles.
• Trunks of elephants
• The snout of the West Indian manatee

The tongue is a muscular hydrostat.  Ever since a defiant student gave me the tongue flap, having picked it up from counterculture intentionally offensive rock bands and knowing what it meant -- which I did not -- I’ve wondered why it was disturbing even without conscious association with sex.  It goes to a more visceral level than the middle finger.  Now I realize that sexual performance and pleasure come from the “muscular hydrostat” function of some bodily parts:  mouth (snout, really, so including upper lip and nose -- as “Eskimo” kissers knew) penis, vagina -- all of them capable of changing shape and equipped with senses of exquisite sensitivity.  Even newborns know to “root” for the nipple and recognize it.  Food, sex, pleasure, survival.  If you think a condom interferes, think of dentures.

Cialis and Viagra work by promoting engorgement of the hydrostatic muscles through the circulation system, which suggests why some people get terrible headaches but also why successful sex can relieve a headache by cycling through engorgement to evacuation.  Cell walls are usually what control intracellular water.  Some scientist is probably quietly investigating the cell walls of those tissues that constitute hydrostatic muscles.  If I knew who they were, I’d ask them about whether brain cells operate in the same way as hydrostatic muscles -- inconveniently confined in the bony vault of the skull. (An octopus has no such restraint on its brain, so it’s big.  Is it because so many neurons are needed to manage its tentacles?  As it turns out, an octopus has everything in its head -- including testicles.)

Interesting that “tongue-flappers” intending offense and intimidation often also use skulls as a motif.  It’s also worth noting that tongue-flapping suggests both penis and vagina, both penetration and engulfment, but in the end it is the brain that notes this across space, without touching, only seeing, using empathy -- which can be powerful enough to take people to orgasm.  (Tentacle porn.)  The skeletally supported middle finger is more of an intellectual symbol.

I’m unclear about whether the rectum is a hydrostatic muscle, but it must be.  There are no bones throughout the intestinal system -- it is all smooth muscle with a few voluntary sphincters.   It’s well-known that the body’s management of the intestines depends upon the management of water -- too little means dry immovable feces, too much means diarrhea.  The nerve network embedded in the intestines works from the same hormonal control molecules (serotonin, et al) that operate the brain.   

Changes throughout the body are generally controlled by hormones, which are molecules created in various organs, distributed through the blood stream and lymph.  Hormone systems plus the sympathetic/parasympathetic nervous system are entwined with emotions, which can mix desire/pain/fear/satisfaction.  Some people will very much resent me even talking about such technicalities, because they feel analysis takes the mystery out of it.  But I am Bibfeldtian: “both/and.”  Knowing how a movie is made does not spoil the illusion for me.

We are in a time when bodies, and particularly the mucous membranes that are markers for hydrostatic muscle tissue, are legally and publicly exposed and invaded in the name of security (since they are often cavities that make good hiding places) and exploited as torture sites, including emotional torture.  In Euro-American cultures the areas are shown explicitly and rather freely, in photos as well as graffiti.  Part of torture is breaking cultural taboo.  And yet I’m reading “The Son,” by Phillip Dreyer, one of those best-selling historical ordeal stories that regularly break taboos by talking about sex and excrement in detail.  The taboo increases the thrill.  Fifty shades of thrill.

Identifying these areas as hydrostatic helps explain why inflammation of them can be erotic, since inflammation concentrates intracellular water, causing swelling and increased circulation.  The tumescence of inflammation is close to erotic engorgement.  This is the principle of Spanish Fly.  But too much inflammation is lethal.

I’ve started a sci-fi story about a girl who has no arms and therefore has tentacles added by surgeons who might transplant them from octopi or might supply robot arms built on those principles.  I always prefer organic, but the suckers are a problem so I’ll have to figure out why and how they need to be removed, but I would leave in the exquisite tactile and taste functions, plus the strength.  Being hugged by someone with tentacle-arms -- what would it be like?  Or what would the person herself feel as she embraced or stroked another.  (The idea of Medusa tentacle-hair is worn out -- anyway, those were snakes and snakes have skeletons.  Not really tentacles.)

Part of this speculation leaves sex alone and goes to memories of an elderly woman in the hospital where I was a chaplain.  Her bones had dissolved.  She couldn’t even sit up in bed.  She was a human mollusk, with a level of frustration beyond rage, verging on madness.  It was not a time to point out to her the pleasures of hydrostatic muscles, nor did the doctors seem able to invent something like a hydrostatic corset that would replace the function of a spine (a hydrostatic backbone).  She was just an unfortunate old woman.  Would a person with tentacle arms be fortunate or unfortunate?