A cat approaches one to one lizard Stop in the sun and, with feline leap, is about to capture it, but the small reptile suddenly loses the tail and runs away. Well yes! Lizard, geckles and other animals are able to lose a stretch of the tail O portions of arts to escape predators: they remain amputated, but alive. The part to be amputated separates in a sort of weak point, but does not involve damage to the animal because it can regenerate over time thanks to a group of stem cells who have the ability to differentiate themselves in various cell lines for reform fabrics. The presence of bundles of nerve cells that keep the muscles active in the newly detached tail allow her to continue to move for a few minutes in order to distract The predator. It is an evolutionary mechanism, called autotomyreally efficient and for this reason very designed also for possible applications in the medical field. The man and most of the other mammals have lost this attitude during the evolution and this is why scientists are trying to find out what the group of genes responsible for the regrowth is, then assuming that they can reactivate their function also in damaged human fabrics. However, this mechanism is not totally free of consequences, since it involves a remarkable energy expenditure For the animal and the appendix it does not grow perfectly identical to the original.
As the amputated tail of lizards does to continue moving alone
The phenomenon of the self-examination was described for the first time by Aristotle as many as 2400 years ago observing lizards, but to reconstruct the entire process were Spallanzani and René Réamur long after, around the mid -18th centuryobserving the salami. The phenomenon is known how autotomy And every species that is able to fulfill it detaches a precise trait of an appendix, distracting the predator.
In the lizard and in the gecko the detachment is rapid And it happens in one precise area in which the vertebrae break more easily because they are crossed by a sort of slit, called “fracture plan“. The lizard suddenly contracts the muscles of the pelvis, breaking the vertebrae and causing the detachment of the tail. At the same time it has been discovered that the lizards have at the level of the breaking point, of the microscopic structures, called nanoporiwhich give great resistance to the tail even if it is tense. In a nutshell, a very resistant appendix, but at the same time able to disengage voluntarily and quickly.
The tail of the lizard and gecko, once lost, continues to move alone for a few minutes (so as to further distract the predator) thanks to the presence of Blazes of nerve cells they keep Activate the muscles. These are groups of neurons able to give impulses independently with respect to the brain and are defined Central pattern generators. The neuromuscular control mechanisms of the amputated tail are not yet well known and this is why a team of researchers from the University of Calgary has carried out an electromyography to the amputated queues of some geckles, implanting electrodes, and has taken them with high -speed cameras. It was possible to observe that the queues move In all directions Rather quickly and which sometimes turn upside down, continuing to oscillate even for 30 minutes. Apparently the different movements of the tail derive from a sort of independent neural circuitswhose operation is not yet clear.
The truck of lizards has high costs
The process of regenerating the tail or limbs is not “a children’s game”, first of all because it involves a remarkable energy expenditure To reconstitute the fabrics. It has been calculated that the energy cost of the synthesis of the tail in the lizard involves a 36% increase in the standard metabolic rate and this energy, in some way, is subtracted from other vital functions. In addition, the limited limbs and appendices do not always maintain the same shape and functionality of the originals and regeneration times are long.
In the crustaceans The complete regeneration of the chela is obtained after several cycles of wetsuit and in the meantime the impairment can influence the efficiency of the nutrition and the phases of the courtship. The lizards and geckles with regenerated queues move less far away and less quickly Compared to those with “original” queues and, therefore, the anti-predation responses also change. Sometimes, a regenerated tail has been observed in specimens of gecki bifid or trifida (i.e. that ends with 2 or 3 points) and this significantly reduces the balance of the specimens.
Which animals are able to lose the tail or a limb
The self-amputation of the tail of the lizard or gecko are perhaps the most studied, but different species of both invertebrates and vertebrates are able to activate this mechanism. The ability of autotomy is reduced during evolution And it is in fact rather rare in mammals. Different species of spiders They lose one of the 8 legs in case of danger, as well as many insects. The crab can lose a chela, i octopus they detach one of the 8 arms To distract the predator, the sea cucumbers (oloturies) are even able to expel the intestine through the anus in case of imminent danger. Star marine even generate new individuals from parts of the body detached due to the effect of trauma.
The phenomenon also occurs in mammalsbut very rarely. Some species of rodents voluntarily detach the tail, but they can’t regenerate it And they remain impaired. Probably the mechanism was also present in prehistoric animals: from recent studies it seems that already the mesosaurs, marine reptiles lived in the upper Cretacic (95-65 million years ago), were capable of losing a trait of the tail.
