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Why is there no such thing as a giant insect?

Aside from science fiction films, we have never seen flies the size of a hawk or centipedes the length of an anaconda. Why are insects mostly tiny?

The largest living insect sur Structure du globe…” data-image=”https://cdn.futura-sciences.com/buildsv6/images/midioriginal/8/4/f/84ff7edce5_123534_terre-apollo8.jpg” data-url=”https://www.futura-sciences.com/planete/definitions/structure-terre-terre-4725/” data-more=”Lire la suite”>terre is a butterfly measuring 35 cm in wingspan, and the largest insect is a The order of Coleoptera includes more than 350,000 species of insects, with complete metamorphosis, with grinding mouthparts, with more or less horny fore wings (elytra (masculine), from Greek "elutron" =…” data-url=”https://www.futura-sciences.com/planete/definitions/zoologie-coleoptere-1675/” data-more=”Lire la suite”>beetle 100 g and 10 cm long. During prehistoric times, however, there were La libellule, from the Odonata group.
Le…” data-image=”https://cdn.futura-sciences.com/buildsv6/images/midioriginal/0/4/a/04aa7af365_92373_shutterstock-rudmer-zwerver.jpg” data-url=”https://www.futura-sciences.com/planete/definitions/insectes-libellule-15869/” data-more=”Lire la suite”>dragonflies 68 cm giants called Meganeura. These have disappeared due to the decline in oxygen levels. Because it is indeed the respiratory system of More … “data-image =” https://cdn.futura-sciences.com/buildsv6/images/midioriginal/c/3/4/c3449c7cc8_49335_def-insecte-mariea- flickr.jpg “data-url =” https://www.futura-sciences.com/planete/definitions/classification-vivant-insecte-2305/ “data-more =” Read more “>insects which prevents them from growing excessively.

Insects: a very specific respiratory system

Unlike Pisces and mammals, insects have neither lung functions
The role of the two lungs is to carry out gas exchange between the human body and the ambient air. These exchanges take place at the level of the alveoli, where the blood is then enriched in oxygen and depleted in carbon dioxide …. “data-image =” https://cdn.futura-sciences.com/buildsv6/images/midioriginal /4/8/3/483ff8575d_50035566_poumons-wwwcfeducationca.jpg “data-url =” https://www.futura-sciences.com/sante/definitions/biologie-poumon-7024/ “data-more =” Read more ” >lungs ni gills. Their shell is pierced with small holes, the Medicine – Non-specific sign or mark that indicates to any observer that the person is sick (thinness or pallor for example). Unlike the sequel, the stigma usually disappears after healing. It does not give … “data-url =” https://www.futura-sciences.com/sante/definitions/medecine-stigmate-2131/ “data-more =” Read more “>stigmata, which carry oxygen in a network of fine canals, the Function of the trachea
The trachea allows oxygen-rich air to pass from the larynx to the lungs, while filtering the air to improve its quality. It is also the elimination route for air rich in carbon dioxide … “data-image =” https://cdn.futura-sciences.com/buildsv6/images/midioriginal/3/a/0/ 3a05f8a302_50034375_systeme-respiratory-wikimedia-03.jpg “data-url =” https://www.futura-sciences.com/sante/definitions/biologie-trachee-2134/ “data-more =” Read more “>tracheae. These ramify throughout their body and deliver oxygen to different tissues. The larger the insect, the more oxygen it needs and the larger and longer and wider the trachea must be to meet oxygen requirements.
However, there is a critical point between the legs and the body, where the opening can no longer be enlarged, which in fact limits the diameter of the trachea. The size of the trachea being limited, the volume of available oxygen is also available and the insect can no longer grow. If prehistoric insects were able to reach such a size, it is because theatmosphere was then richer in oxygen ; so lessair crossing the trachea to provide the same amount of oxygen. According to the researchers’ calculations, the maximum size that an insect can reach with the current oxygen level is about 15 cm (this is precisely the record).

Meganeura, the largest insect to ever live on Earth, measured almost 70 cm in wingspan.  © Romain Garrouste, MNHN

Skeleton, birds, flight: from handicaps to giant insects

Other hypotheses are put forward to explain why there is no such thing as a giant insect:

  • Insects have no internal skeleton but a Zoology
    The exoskeleton, or cuticle, is the hard outer shell of an arthropod (crustacean, insect, arachnid, etc.). It protects the animal and serves as a grip on the muscles, allowing movement, like … “data-image =” https://cdn.futura-sciences.com/buildsv6/images/midioriginal/1/c/9 /1c9957228d_50034208_dryococelus-australis-pterhalasz-wikimedia.jpg “data-url =” https://www.futura-sciences.com/planete/definitions/zoologie-exosquelette-433/ “data-more =” Read more “>exosquelette composed of chitine. The latter would have to be much too thick if it had to support too much weight.
  • Too large a size would expose them more to predators. A 2012 study emphasizes that the decline of giant insects coincides with the arrival of bat and the advent of birds. The latter would also have competed with giant insects by feeding on the same small insects.
  • Butterflies with too large wings would be difficult to maneuver in strong vent.
  • Finally, the small size of insects gives them a number of developmental advantages. The flea can jump nearly 340 times its own size, and the Ant Genres: Army Ants and Atta Ants
    Les…” data-image=”https://cdn.futura-sciences.com/buildsv6/images/midioriginal/5/6/6/566793976d_93683_shutterstock-pavel-krasensky.jpg” data-url=”https://www.futura-sciences.com/planete/definitions/insectes-fourmi-15969/” data-more=”Lire la suite”>ant can carry 1,000 times its weight. Performs to make men green with envy.

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