L’araignée qui se prenait pour un paon
Pour ce premier post, j’ai choisi une espèce qui allie la beauté du paon à la crainte que peuvent inspirer les araignées. Le bestiaire qui enrichira progressivement ces pages oscillera entre ces deux extrêmes, l’élégance et la répugnance.
Un Post Scriptum tout de suite, avant notre « bestiole du jour » : n’hésitez pas à me proposer des idées !
Commençons par la carte d’identité pour les spécialistes et les amateurs de phylogénie. Les araignées du genre Maratus sont des arthropodes du sous-ordre des aranéomorphes, de la famille des araignées sauteuses (les Salticidae). Celles qui nous intéressent sont endémiques des États du Queensland et des Nouvelle-Galles-du-Sud, en Australie. Pas de quoi effrayer les arachnophobes, l’animal ne mesure que quelques millimètres. Ses grands yeux sont typiques des araignées sauteuses qui ne tissent pas de toile, mais bondissent sur leurs proies : ce comportement s’est traduit par la sélection (naturelle) d’une vue perçante.
Le plus étonnant est l’abdomen des mâles. Il est flanqué de deux appendices, d’ordinaire repliés sous le corps. Ils se déploient au moment de la parade nuptiale. Face à une femelle, le mâle redresse alors deux de ses huit pattes et exhibe son abdomen étendu iridescent et paré de mille couleurs selon un motif propre à chaque espèce. Ces attributs ont valu à l’araignée son nom anglais, peacock spider, c’est-à-dire l’araignée-paon. Cette démonstration s’accompagne d’une danse frénétique : il s’agit de se montrer au mieux de sa forme pour convaincre la femelle de sa bonne santé, promesse de descendance vigoureuse. La pression sur les mâles est énorme : ceux qui ne conviennent pas à une femelle pour un accouplement seront, à défaut, un excellent mets !
Quand il les décrivit pour la première fois, à la fin du XIXe siècle, le révérend, et zoologiste à ses heures, Octavius Pickard-Cambridge (1828-1917) indiqua: « C’est difficile de trouver les mots pour décrire la richesse et la beauté des couleurs de ces araignées ». Qu’en pensez-vous ?
Maratus speciosus © J. Otto
Maratus volans © J. Otto
Maratus splendens © J. Otto
Maratus amabilis © J. Otto
Une espèce encore sans nom du genre Maratus. © J. Otto
Et une vidéo :
Quelques références pour en savoir plus :
- J. C. Otto et D. E. Hill, An illustrated review of the known peacock spiders of the genus Maratus from Australia, with description of a new species (Araneae : Salticidae : Euophryinae), Peckhamia, vol. 96.1, 2011.
- M. B. Girard, M. M. Kasumovic et D. O. Elias, Multi-modal courtship in the peacock spider, Maratus volans (O.P.-Cambridge, 1874), PLoS ONE, vol. 6(9), e25390, 2011.
- Plusieurs vidéos d'araignées paon sur la chaine YouTube de J. Otto.
- Par ailleurs, devenez Fan des araignées paon sur leur page Facebook !
Tres joli post ! Cette araignée papillon que je connaissais pas est vraiment impressionnante !
Araignée paon, plutôt que papillon.
Incroyable! chez Maratus volans, on dirait un dessin de Pablo Picasso sur la bête !
Très belle preuve de la diversité des moyens et créativité sans limite dont dispose notre bonne mère nature surtout pour la procréation des espèces.
Les questions que je me pose sont celle de la vision des femelles araignées Maratus, est-on certain que la beauté picturale démontrée sur ces photos, celle que l'on voit reste préservée pour la capacité visuelle des araignées? que voient-elles réellement, le sait-on?. Par ailleurs, y-a-t-il pour les araignées du sens plus large à la symbolique différentiée des motifs sur l'abdomen en fonction des familles si ce n'est la distinction ou confirmation d'appartenance à une même famille. D'ailleurs est-elle systématique pour les araignées d'une même famille?.
La vision dépend de l'espèce. D'une façon générale, la plupart des araignées ont huit yeux simples (par opposition aux yeux à facettes des insectes) et ont une vision le plus souvent mauvaise. Mais les araignées qui chassent, telles les Salticidae et donc celles du genre Maratus sont une exception : elles ont une très bonne vision. Elles sont ainsi capables de repérer une proie à plus de deux mètres, ce qui pour un animal de quelques millimètres est une performance.
Le 27 janvier 2012, une étude parus dans Science avait montré que les araignées évaluent la profondeur de champ en comparant une image nette et une autre floue, les deux se formant à des endroits différents de la rétine (celles des deux plus gros yeux des araignées sauteuses est constituée de quatre couches de cellules photosensibles, la rétine humaine n'en ayant qu'une seule!). L'intensité du flou renseignerait l'animal sur la distance à laquelle l’objet se trouve par rapport à l’œil.
Quand aux couleurs, au moins quatre des huit yeux sont sensibles aux couleurs et l'on a identité des photorécepteurs sensibles au vert, au rouge et aux ultraviolets. Avec ces trois types de récepteurs, les araignées femelles Maratus sont suffisamment équipées pour détecter les couleurs des abdomens des mâles, même si elles les voient sans doute différemment de ce que nous voyons.
N.B. On a découvert en 2012 une espèce d'araignée sauteuse vivant des des grottes au Laos. Elle chasse et pourtant... elle n'a pas d'yeux.
Super merci pour ces réponses
Peut-être une candidate pour une future bestiole du jour : Prohierodula pista (famille des Mantidae)
désolé de la faute de frappe: Prohierodula picta (un artefact de mon super ordi)
Merci ! Les vidéos sont fantastiques !
incroyable ce que peut nous livrer la nature
Je pense qu'elle n'a pas fini de nous étonner dame nature
wow!! This spider have the amazing colors and looks amazing. Thanks to aware us with this beautiful creature.
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