The fleasmall insects hematophagesfeed on blood and take refuge in humid and shaded environments, both inside and outside the buildings. Despite theirs small sizewith females 4-5 mm and smaller males long, they are equipped with an extraordinary ability: jumping incredible distances, up to 30 times their length, and in some cases even 100 times. These jumps are possible thanks to a “evolutionary makeup“Extraordinary represented by resilinea protein that works like a sort of “biological spring” store elastic energy and release it In a moment for onelightning acceleration. In recent decades, scientific studies have the jump mechanism gradually clarifiedhighlighting the role of resiline and the structure of the rear legs that allows you to direct and orient the jump to the best.
Fleas jump in three phases
The jump of fleas is a complex mechanism based on a System of accumulation and release of energy. The process takes place through Several key steps: preparation of the jump; Release of energy and push towards the ground; Trajectory and leap control.
During the phase of preparation of the jumpfleas begin to position the rear legs, crouched in one configuration which could be defined as “in office“. During this phase, the equipmentral muscles contract and compress the chest. resilinean elastic protein that is able to store and release large quantities of energy. Resilina, at this point, is loaded with elastic energy like a tense spring. To prevent this energy from being released immediately, the joints of the rear legs are blocked.
Once the energy has been accumulated, the terminal part of the rear legs gives one pushed towards the ground. In this way the block of the joints is released, the Resilina expands quickly And transforms the elastic energy accumulated into movement. This mechanism allows an extremely rapid acceleration, with values of about 100 times the acceleration of terrestrial gravity.
The way the force is transferred to the ground (practically as the legs push on the ground) determines thejump orientation. Two historical hypotheses had tried to explain this aspect: theRothschild hypothesisaccording to which the push is transmitted through the trochanter (a part of the rear paw very similar to a knee in contact with the ground), el ‘Bennet-Clark hypothesisaccording to which force is applied through the tibia and tarsus.
The most recent studies, however, using electronic microscopy and high -speed kinetic analysis to investigate the phenomenon, have shown that the Second hypothesis is correct: The thrust force is transmitted through the tibia and tarsus, and not from the trochanger. This mechanism allows a Best control of the management of the jump And it allows fleas to modulate the trajectory.
La Resilina: the protein to jump
Resilina is an elastic protein that is found in many insects and its function is to store and release energy efficiently. The mechanical properties of this protein are out of the ordinary, in fact Resilina can be compressed and released with aenergy efficiency greater than 90%making it one of the biological elastic materials more performing known to date. Studies conducted with fluorescence microscopy have shown that resiline in fleas is found in specific regions of the chest.
This protein comes progressively loaded and then released in a fraction of millisecondallowing the flea to speed up quickly without requesting direct muscle force.
Comparison with other talked insects
Fleas is not the only insects to exploit a mechanism of accumulation and release of energy for the jump. For example, the Snow fleas (Boreus Hyemalis), belonging to the Mecoptera order, use a similar system. However, they use not only the rear legs, but also the median ones for the jump. This suggests a possible evolutionary link between these insects and real fleas. Other insects such as ride and flea choleotteri also use resiline for the jump, but with a different distribution within their bodies.
The understanding of the mechanisms with here these insects can perform their amazing jumps offers ideas for possible applications in robotics and materials of materials, exploiting the properties seen to develop New propulsion systems Elastic and efficient.
