Bacino e coda chakasa
Chakasa pelvis and tail

di leonardo maffi e Alessio "Scale" Scalerandi
by leonardo maffi and Alessio "Scale" Scalerandi

Versione 1.4 del 28 luglio 2004
Version 1.4, july 28 2004

Bacino, osso sacro, e ossa coda chakasa.
Chakasa pelvis, sacrum and tail bones.

Forse esistono modi migliori e più leggeri per progettare una coda, ad esempio ispirandosi alla coda prensile di Corucia zebrata (Solomon Islands skink), studiata da Kevin C. Zippel:
Probably there are better and lighter designs for a Prehensile Tail, for example the design of the Corucia zebrata (Solomon Islands skink) tail, studied by Kevin C. Zippel:

Corucia zebrata, una lucertola delle isole Salomone, uno scincide.
Corucia zebrata, the Solomon Island Skink, "Prehensile Tail" or "Monkey Tail" skink.

Osso sacro chakasa (con una ampia superficie per l'attacco dei muscoli e tendini della coda, che è molto potente e muscolare. Questo design è ispirato dalla parte anteriore del cranio di elefante, dove ci sono gli attacchi per i muscoli della proboscide, e un po' anche dal bacino di certi dinosauri dotati di una coda robusta). Il punto A mostra dove l'osso sacro è connesso con l'ileo.
Chakasa sacrum, with a large area for a strong connection with the tail muscles.

Bacino e coda di leonessa, per confronto.
Lioness pelvis and tail, for comparisons.

Bacino umano, per confronto.
Human pelvis, for comparisons.

Cranio d'elefante, per confronto. (Una proboscide d'elefante pesa circa 100-140 kg ed è lunga circa 2 m, può sollevare 200-400 kg a seconda delle dimensioni dell'elefante. L'intero corpo umano ha circa 639 muscoli, mentre una proboscide d'elefante ha circa 100.000 muscoli).
Elephant skull, for comparisons (An elephant trunk weighs about 140 kilograms (300 pounds), is about long 2 meters long (seven feet) and can lift 200-400 kg. The human body has about 639 muscle, the elephant trunk contains more than 100,000 muscles.)

Osso sacro chakasa, con una ampia superficie per l'attacco dei muscoli della coda.
Chakasa sacrum, with a large area for a strong connection with the tail muscles.

Punte della coda chakasa: 1 = coda normale, vista da sopra. 2 = coda con punta osso-cornea sviluppata (es. come quella di Tigrerossa), vista da sopra. 3 = con arma di metallo e cuoio. 4 = sul lato inferiore della punta della coda c'è una zona di pelle nuda che migliora la presa (dello stesso colore della pelliccia), detta "codastrello".
Chakasa tailtips: 1 = normal tailtip, upper view. 2 = tail tip with developed horned point, upper view. 3 = with a weapon made of metal and leather. 4 = on the lower side of the tail tip there is with a furless grippin skin patch (same colour of the fur).

Ultima vertebra della coda chaakasa, con organi a sigaro, e punta osso-cornea non sviluppata e sviluppata.
Last chakasa tail vertebra with cygar-shaped organs, with a not developed horn point and with the point.

Struttura delle vertebre della coda chaakasa; ciascuna è incastrata nella successiva con una articolazione sferica (ma in effetti di solito tali articolazioni si piegano di pochi gradi ciascuna). Le vertebre finali sono piatte e molto più leggere, e sono agganciate con le vicine solo orizzontalmente e non verticalmente.
Chakasa tail vertebrae design.

More about the "Monkey Tail" skink, cited from Cornell Science News, 1994:
  Solomon Islands skinks (Corucia zebrata) evolved an important adaptation for their leisurely lifestyle: a prehensile (or grasping) tail that coils around branches like a corkscrew, serves as a fifth limb when the front legs are busy and saves the lizard if it starts to fall.
   Kevin C. Zippel, a longtime keeper of pet lizards and Cornell senior in biological sciences, performed a comparative anatomical analysis of the skink tail and other muscle arrangements. He found a system that is rare in the animal world and previously undocumented in animal tails. Zippel discovered bundles of cone-shaped muscles, "Like stacks of sno-cones," as he puts it, that are strongly attached to a tunic-like sheath but barely attached to the bones of its tail vertebrae. Between the muscle bundles and the bone is a layer of energy-storing fat. The muscle arrangement is so unusual that it defies comparison.
   "Lots of animals have prehensile organs," said Zippel, who did the study for a senior honors thesis. "Prehensile monkey tails are articulated linkages, and they work like our arms, with flexor and extensor muscles and the attached bones serving as points of support and resistance to compressive forces. The other main system is the muscular hydrostat, like an elephant's trunk, where there is no bone but the muscles on one side shorten, the other side lengthens and a tendinous sheath prevents a change in circumference."
   It was not until the late 1970s that a third, combined muscle arrangement was described in sharks, Zippel noted. Sharks' distinctive swimming motion comes from conical muscles that are connected to their vertebral columns as well as to three-dimensional arrays of tendons in and around their muscles. And shark muscles are the closest comparison to what the student found in the skink tail, according to John E.A. Bertram, assistant professor of anatomy in Cornell's College of Veterinary Medicine and Zippel's adviser.
   Under Bertram's tutelage, Zippel presented his findings July 29 to the Society for the Study of Amphibians and Reptiles in Athens, Ga. He is preparing an article for the Journal of Morphology.
   "This study of skinks and chameleons demonstrates the independent derivation (in evolution) of prehensile tails," Bertram commented. "In evolution, there is often no single, perfect solution and usually several adequate solutions." At Cornell, Bertram teaches classes in biomechanics.
   The omnidirection capability of the skink tails gives Zippel and Bertram an idea for a better robot. Most robotic appendages are patterned on the human arm and wrist; they move back and forth, up and down, and sometimes rotate.
    "Skink tails, with their stacks of muscle cones, have them all beat," Zippel said. "One part of the tail can remain rigid while other parts are flexible, and they can twist and turn in virtually any direction. The tail alone can support the weight of the entire animal," he said, noting the morphological definition of a prehensile tail. "Robotics engineers should check them out."

[Vedi anche la pagina di Scale - See Scale's page too]

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