{"id":4671,"date":"2026-01-14T13:12:01","date_gmt":"2026-01-14T02:12:01","guid":{"rendered":"https:\/\/www.babou-plongee.com\/blog\/?page_id=4671"},"modified":"2026-04-03T09:15:55","modified_gmt":"2026-04-02T22:15:55","slug":"janthina-janthina-le-petit-escargot-violet-des-oceans","status":"publish","type":"page","link":"https:\/\/www.babou-plongee.com\/blog\/janthina-janthina-le-petit-escargot-violet-des-oceans\/","title":{"rendered":"Janthina janthina \u2013 Le Petit Escargot Violet des Oc\u00e9ans"},"content":{"rendered":"<p data-start=\"456\" data-end=\"824\">Cette page est un compl\u00e9ment d&rsquo;information au sujet de <a href=\"https:\/\/www.babou-plongee.com\/blog\/le-petit-escargot-violet-des-oceans\/\">l&rsquo;article de notre blog consacr\u00e9 \u00e0 Janthina l&rsquo; Escargot Violet des Oc\u00e9ans.<\/a><\/p>\n<p data-start=\"456\" data-end=\"824\">Elle est le r\u00e9sultat de la compilation de diff\u00e9rents sites.<\/p>\n<p data-start=\"456\" data-end=\"824\">Ce petit mollusque marin est l\u2019un des organismes les plus surprenants du <strong data-start=\"529\" data-end=\"541\">pleuston<\/strong> \u2013 la communaut\u00e9 d\u2019animaux vivant \u00e0 la surface de l\u2019oc\u00e9an. Malgr\u00e9 sa taille modeste et sa coquille d\u00e9licate, <em data-start=\"650\" data-end=\"669\">Janthina janthina<\/em> est une cr\u00e9ature fascinante qui illustre parfaitement l\u2019adaptation \u00e0 un habitat extr\u00eame : la surface libre de l\u2019eau.<\/p>\n<table class=\" aligncenter\" style=\"width: 100%; border-collapse: collapse;\">\n<tbody>\n<tr>\n<td style=\"width: 50%;\"><a href=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180220.jpg?ssl=1\"><img alt=\"\" loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-4692\" src=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180220.jpg?resize=744%2C496&#038;ssl=1\" alt=\"\" width=\"744\" height=\"496\" srcset=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180220.jpg?resize=744%2C496&amp;ssl=1 744w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180220.jpg?resize=420%2C280&amp;ssl=1 420w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180220.jpg?w=1200&amp;ssl=1 1200w\" sizes=\"(max-width: 744px) 100vw, 744px\" data-recalc-dims=\"1\" \/><\/a><\/td>\n<td style=\"width: 50%;\"><a href=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180238.jpg?ssl=1\"><img alt=\"\" loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-4694\" src=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180238.jpg?resize=744%2C496&#038;ssl=1\" alt=\"\" width=\"744\" height=\"496\" srcset=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180238.jpg?resize=744%2C496&amp;ssl=1 744w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180238.jpg?resize=420%2C280&amp;ssl=1 420w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180238.jpg?w=1200&amp;ssl=1 1200w\" sizes=\"(max-width: 744px) 100vw, 744px\" data-recalc-dims=\"1\" \/><\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 50%;\"><a href=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180204.jpg?ssl=1\"><img alt=\"\" loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-4691\" src=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180204.jpg?resize=744%2C496&#038;ssl=1\" alt=\"\" width=\"744\" height=\"496\" srcset=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180204.jpg?resize=744%2C496&amp;ssl=1 744w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180204.jpg?resize=420%2C280&amp;ssl=1 420w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180204.jpg?w=1200&amp;ssl=1 1200w\" sizes=\"(max-width: 744px) 100vw, 744px\" data-recalc-dims=\"1\" \/><\/a><\/td>\n<td style=\"width: 50%;\"><a href=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180143.jpg?ssl=1\"><img alt=\"\" loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-4690\" src=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180143.jpg?resize=744%2C496&#038;ssl=1\" alt=\"\" width=\"744\" height=\"496\" srcset=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180143.jpg?resize=744%2C496&amp;ssl=1 744w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180143.jpg?resize=420%2C280&amp;ssl=1 420w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-180143.jpg?w=1200&amp;ssl=1 1200w\" sizes=\"(max-width: 744px) 100vw, 744px\" data-recalc-dims=\"1\" \/><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr data-start=\"826\" data-end=\"829\" \/>\n<h2 id=\"-apparence-et-habitat\" data-start=\"831\" data-end=\"861\"><strong data-start=\"834\" data-end=\"861\"> Apparence et Habitat<\/strong><\/h2>\n<p data-start=\"863\" data-end=\"1141\"><em data-start=\"863\" data-end=\"882\">Janthina janthina<\/em> est un <strong data-start=\"890\" data-end=\"905\">gast\u00e9ropode<\/strong> marin d\u2019eau sal\u00e9e qui passe <strong data-start=\"934\" data-end=\"974\">toute sa vie \u00e0 la surface de l\u2019oc\u00e9an<\/strong>, jamais au fond. Son corps et sa coquille ont une <strong data-start=\"1025\" data-end=\"1051\">couleur violet intense<\/strong>, ce qui lui donne son nom commun d\u2019escargot violet.<\/p>\n<p data-start=\"1143\" data-end=\"1156\">Sa coquille :<\/p>\n<ul data-start=\"1157\" data-end=\"1500\">\n<li data-start=\"1157\" data-end=\"1290\">\n<p data-start=\"1159\" data-end=\"1290\">est <strong data-start=\"1163\" data-end=\"1188\">tr\u00e8s fragile et mince<\/strong>, souvent de quelques centim\u00e8tres de diam\u00e8tre (jusqu\u2019\u00e0 ~4 cm).<\/p>\n<\/li>\n<li data-start=\"1291\" data-end=\"1500\">\n<p data-start=\"1293\" data-end=\"1500\">pr\u00e9sente un <strong data-start=\"1305\" data-end=\"1331\">contre-ombrage invers\u00e9<\/strong> : la face inf\u00e9rieure de la coquille (qui est vers le haut quand il flotte) est plus sombre, ce qui aide \u00e0 se camoufler en surface.<\/p>\n<\/li>\n<\/ul>\n<p data-start=\"1502\" data-end=\"1727\">L\u2019escargot vit \u00e0 la <strong data-start=\"1522\" data-end=\"1586\">surface des oc\u00e9ans tropicaux et subtropicaux du monde entier<\/strong> (distribution circumequatoriale), dans des zones o\u00f9 les courants concentrent les organismes flottants.<\/p>\n<hr data-start=\"1729\" data-end=\"1732\" \/>\n<h2 id=\"-mode-de-vie-et-d\u00e9placements\" data-start=\"1734\" data-end=\"1771\"><strong data-start=\"1737\" data-end=\"1771\"> Mode de Vie et D\u00e9placements<\/strong><\/h2>\n<p data-start=\"1773\" data-end=\"1972\">Contrairement \u00e0 la plupart des escargots marins, <em data-start=\"1822\" data-end=\"1841\">Janthina janthina<\/em> ne nage pas et ne marche pas sur le fond. Il se maintient en surface gr\u00e2ce \u00e0 un <strong data-start=\"1922\" data-end=\"1946\">\u00ab radeau de bulles \u00bb<\/strong> qu\u2019il fabrique lui-m\u00eame :<\/p>\n<ul data-start=\"1974\" data-end=\"2228\">\n<li data-start=\"1974\" data-end=\"2065\">\n<p data-start=\"1976\" data-end=\"2065\">Il s\u00e9cr\u00e8te un <strong data-start=\"1991\" data-end=\"2008\">mucus collant<\/strong> depuis son pied.<\/p>\n<\/li>\n<li data-start=\"2066\" data-end=\"2228\">\n<p data-start=\"2068\" data-end=\"2228\">En y emprisonnant des bulles d\u2019air, il construit une <strong data-start=\"2121\" data-end=\"2144\">structure flottante<\/strong> qui l\u2019aide \u00e0 rester en permanence en surface.<\/p>\n<\/li>\n<\/ul>\n<p data-start=\"2230\" data-end=\"2389\">Si ce radeau se d\u00e9tache ou se rompt, l\u2019animal <strong data-start=\"2276\" data-end=\"2301\">ne peut plus remonter<\/strong> \u00e0 la surface et coule, ce qui est fatal pour lui.<\/p>\n<p data-start=\"2391\" data-end=\"2678\">Ainsi, ses <strong data-start=\"2402\" data-end=\"2418\">d\u00e9placements<\/strong> ne sont pas actifs : il d\u00e9rive <strong data-start=\"2450\" data-end=\"2486\">au gr\u00e9 des vents et des courants<\/strong>. Lors de vents forts ou de temp\u00eates, des milliers d\u2019individus peuvent se retrouver <strong data-start=\"2570\" data-end=\"2590\">\u00e9chou\u00e9s ensemble<\/strong> sur les plages, comme observ\u00e9 ici.<\/p>\n<hr data-start=\"2680\" data-end=\"2683\" \/>\n<h2 id=\"\ufe0f-alimentation\" data-start=\"2685\" data-end=\"2708\"><strong data-start=\"2688\" data-end=\"2708\">\ufe0f Alimentation<\/strong><\/h2>\n<p data-start=\"2710\" data-end=\"2808\"><em data-start=\"2710\" data-end=\"2729\">Janthina janthina<\/em> est un <strong data-start=\"2737\" data-end=\"2761\">pr\u00e9dateur sp\u00e9cialis\u00e9<\/strong> des organismes qui vivent aussi \u00e0 la surface :<\/p>\n<ul data-start=\"2810\" data-end=\"3208\">\n<li data-start=\"2810\" data-end=\"3208\">\n<p data-start=\"2812\" data-end=\"2883\">Il se nourrit principalement de <strong data-start=\"2844\" data-end=\"2870\">cnidaires n\u00e9ustoniques<\/strong> tels que :<\/p>\n<ul data-start=\"2886\" data-end=\"3208\">\n<li data-start=\"2886\" data-end=\"2955\">\n<p data-start=\"2888\" data-end=\"2955\"><em data-start=\"2888\" data-end=\"2909\"><strong data-start=\"2889\" data-end=\"2908\">Velella velella<\/strong><\/em> (les \u00ab voiliers \u00bb ou <em data-start=\"2931\" data-end=\"2952\">by-the-wind sailors<\/em>)<\/p>\n<\/li>\n<li data-start=\"2958\" data-end=\"3018\">\n<p data-start=\"2960\" data-end=\"3018\"><em data-start=\"2960\" data-end=\"2983\"><strong data-start=\"2961\" data-end=\"2982\">Physalia physalis<\/strong><\/em> (gal\u00e8re portugaise \/ bluebottle)<\/p>\n<\/li>\n<li data-start=\"3021\" data-end=\"3208\">\n<p data-start=\"3023\" data-end=\"3208\"><em data-start=\"3023\" data-end=\"3044\"><strong data-start=\"3024\" data-end=\"3043\">Porpita porpita<\/strong><\/em><br data-start=\"3044\" data-end=\"3047\" \/>Ces petites cr\u00e9atures flottantes sont souvent confondues avec des m\u00e9duses et sont <strong data-start=\"3129\" data-end=\"3169\">leur principale source de nourriture<\/strong>.<\/p>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p data-start=\"3210\" data-end=\"3440\">J&rsquo;ai photographi\u00e9 de petites <em data-start=\"3254\" data-end=\"3264\">Physalis<\/em> sur la plage : ce sont probablement des <strong data-start=\"3305\" data-end=\"3324\">proies directes<\/strong> de ces escargots violets ! C\u2019est un bel exemple d\u2019interaction trophique directement observable apr\u00e8s un \u00e9chouage.<\/p>\n<p data-start=\"3442\" data-end=\"3582\">L\u2019escargot utilise un <strong data-start=\"3464\" data-end=\"3488\">proboscis extensible<\/strong> pour capturer et consommer ces organismes g\u00e9latineux.<\/p>\n<table class=\" aligncenter\" style=\"width: 100%; border-collapse: collapse;\">\n<tbody>\n<tr>\n<td style=\"width: 50%;\"><a href=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-083444.jpg?ssl=1\"><img alt=\"\" loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-4688\" src=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-083444.jpg?resize=744%2C496&#038;ssl=1\" alt=\"\" width=\"744\" height=\"496\" srcset=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-083444.jpg?resize=744%2C496&amp;ssl=1 744w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-083444.jpg?resize=420%2C280&amp;ssl=1 420w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-083444.jpg?w=1200&amp;ssl=1 1200w\" sizes=\"(max-width: 744px) 100vw, 744px\" data-recalc-dims=\"1\" \/><\/a><\/td>\n<td style=\"width: 50%;\"><a href=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-084103.jpg?ssl=1\"><img alt=\"\" loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-4689\" src=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-084103.jpg?resize=744%2C496&#038;ssl=1\" alt=\"\" width=\"744\" height=\"496\" srcset=\"https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-084103.jpg?resize=744%2C496&amp;ssl=1 744w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-084103.jpg?resize=420%2C280&amp;ssl=1 420w, https:\/\/i0.wp.com\/www.babou-plongee.com\/blog\/wp-content\/uploads\/2026\/01\/Babou-Cote-Ocean-084103.jpg?w=1200&amp;ssl=1 1200w\" sizes=\"(max-width: 744px) 100vw, 744px\" data-recalc-dims=\"1\" \/><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr data-start=\"3584\" data-end=\"3587\" \/>\n<h2 id=\"\u2764\ufe0f-reproduction-et-cycle-d\" data-start=\"3589\" data-end=\"3627\"><strong data-start=\"3592\" data-end=\"3627\">Reproduction et Cycle de Vie<\/strong><\/h2>\n<p data-start=\"3629\" data-end=\"3723\">L\u2019un des traits les plus \u00e9tonnants de <em data-start=\"3667\" data-end=\"3686\">Janthina janthina<\/em> est sa <strong data-start=\"3694\" data-end=\"3721\">strat\u00e9gie reproductrice<\/strong> :<\/p>\n<ul data-start=\"3725\" data-end=\"4430\">\n<li data-start=\"3725\" data-end=\"3923\">\n<p data-start=\"3727\" data-end=\"3923\">L\u2019esp\u00e8ce est <strong data-start=\"3740\" data-end=\"3756\">protandrique<\/strong> : les individus commencent leur vie en tant que <strong data-start=\"3805\" data-end=\"3814\">m\u00e2les<\/strong>, puis se transforment en <strong data-start=\"3840\" data-end=\"3852\">femelles<\/strong> \u00e0 mesure qu\u2019ils grandissent.<\/p>\n<\/li>\n<li data-start=\"3924\" data-end=\"4099\">\n<p data-start=\"3926\" data-end=\"4099\">Les <strong data-start=\"3930\" data-end=\"3939\">m\u00e2les<\/strong> produisent du sperme qui est lib\u00e9r\u00e9 vers l\u2019ext\u00e9rieur, et la f\u00e9condation a lieu lorsque le sperme atteint une femelle.<\/p>\n<\/li>\n<li data-start=\"4100\" data-end=\"4300\">\n<p data-start=\"4102\" data-end=\"4300\">Les <strong data-start=\"4106\" data-end=\"4114\">\u0153ufs<\/strong> sont <strong data-start=\"4120\" data-end=\"4142\">retenus et incub\u00e9s<\/strong> par la femelle jusqu\u2019\u00e0 ce qu\u2019ils \u00e9closent en une <strong data-start=\"4192\" data-end=\"4209\">larve veliger<\/strong> (larve nageuse), qui poss\u00e8de encore un opercule.<\/p>\n<\/li>\n<li data-start=\"4301\" data-end=\"4430\">\n<p data-start=\"4303\" data-end=\"4430\">Ces larves nagent avant de devenir adultes et de produire leur propre radeau de bulles.<\/p>\n<\/li>\n<\/ul>\n<hr data-start=\"4432\" data-end=\"4435\" \/>\n<h2 id=\"-distribution-g\u00e9ographique\" data-start=\"4437\" data-end=\"4472\"><strong data-start=\"4440\" data-end=\"4472\"> D<\/strong><strong data-start=\"4440\" data-end=\"4472\">istribution G\u00e9ographique<\/strong><\/h2>\n<p data-start=\"4474\" data-end=\"4553\"><em data-start=\"4474\" data-end=\"4493\">Janthina janthina<\/em> est une esp\u00e8ce <strong data-start=\"4509\" data-end=\"4521\">mondiale<\/strong> des eaux chaudes ou temp\u00e9r\u00e9es :<\/p>\n<ul data-start=\"4555\" data-end=\"4987\">\n<li data-start=\"4555\" data-end=\"4660\">\n<p data-start=\"4557\" data-end=\"4660\">Pr\u00e9sente dans <strong data-start=\"4571\" data-end=\"4617\">les oc\u00e9ans Atlantique, Pacifique et Indien<\/strong>.<\/p>\n<\/li>\n<li data-start=\"4661\" data-end=\"4811\">\n<p data-start=\"4663\" data-end=\"4811\">Fr\u00e9quemment <strong data-start=\"4675\" data-end=\"4732\">trouv\u00e9e \u00e9chou\u00e9e apr\u00e8s des temp\u00eates ou des vents forts<\/strong> sur des plages de divers continents.<\/p>\n<\/li>\n<li data-start=\"4812\" data-end=\"4987\">\n<p data-start=\"4814\" data-end=\"4987\">En Australie, on la trouve sur les c\u00f4tes tropicales et temp\u00e9r\u00e9es, mais elle est aussi signal\u00e9e dans bien d\u2019autres r\u00e9gions tropicales.<\/p>\n<\/li>\n<\/ul>\n<hr data-start=\"4989\" data-end=\"4992\" \/>\n<h2 id=\"-pourquoi-on-les-voit-souvent-\" data-start=\"4994\" data-end=\"5047\"><strong data-start=\"4997\" data-end=\"5047\"> Pourquoi on les voit souvent sur la plage ?<\/strong><\/h2>\n<p data-start=\"5049\" data-end=\"5157\">Ces escargots ne sont <strong data-start=\"5071\" data-end=\"5115\">pas des habitants permanents du littoral<\/strong> : ils d\u00e9rivent en pleine mer. Cependant :<\/p>\n<ul data-start=\"5159\" data-end=\"5468\">\n<li data-start=\"5159\" data-end=\"5313\">\n<p data-start=\"5161\" data-end=\"5313\">Lors de <strong data-start=\"5169\" data-end=\"5199\">\u00e9v\u00e9nements m\u00e9t\u00e9orologiques<\/strong> (vents, courants, temp\u00eates), leur radeau peut \u00eatre pouss\u00e9 vers la c\u00f4te.<\/p>\n<\/li>\n<li data-start=\"5314\" data-end=\"5468\">\n<p data-start=\"5316\" data-end=\"5468\">Ils sont <strong data-start=\"5325\" data-end=\"5353\">ultra l\u00e9gers et fragiles<\/strong>, donc ils se retrouvent facilement sur le rivage, souvent en grand nombre.<\/p>\n<\/li>\n<\/ul>\n<p data-start=\"5470\" data-end=\"5665\">C\u2019est probablement ce qui a caus\u00e9 <strong data-start=\"5504\" data-end=\"5544\">l\u2019\u00e9chouage r\u00e9cent \u00e0 Hiengh\u00e8ne<\/strong>\u00a0: une combinaison de courants et de vents qui ont pouss\u00e9 ces organismes en surface vers la plage.<\/p>\n<hr data-start=\"5667\" data-end=\"5670\" \/>\n<h2 id=\"-\u00c0-retenir\" style=\"padding-left: 40px;\" data-start=\"5672\" data-end=\"5691\"><strong data-start=\"5675\" data-end=\"5691\"> <span style=\"color: #339966;\">\u00c0 retenir<\/span><\/strong><\/h2>\n<p style=\"padding-left: 40px;\" data-start=\"5693\" data-end=\"6320\"><span style=\"color: #339966;\">\u2714 <em data-start=\"5695\" data-end=\"5714\">Janthina janthina<\/em> est un <strong data-start=\"5722\" data-end=\"5758\">esp\u00e8ce pelagique et pleustonique<\/strong> qui ne vit qu\u2019\u00e0 la surface de l\u2019eau gr\u00e2ce \u00e0 un <strong data-start=\"5806\" data-end=\"5826\">radeau de bulles<\/strong> qu\u2019elle construit elle-m\u00eame. <\/span><br data-start=\"5895\" data-end=\"5898\" \/><span style=\"color: #339966;\">\u2714 Elle se nourrit principalement de <strong data-start=\"5934\" data-end=\"5957\">cnidaires flottants<\/strong> comme <em data-start=\"5964\" data-end=\"5973\">Velella<\/em> et <em data-start=\"5977\" data-end=\"5987\">Physalia<\/em>. <\/span><br data-start=\"6028\" data-end=\"6031\" \/><span style=\"color: #339966;\">\u2714 Elle a une <strong data-start=\"6044\" data-end=\"6076\">biologie reproductive unique<\/strong>, changeant de sexe au cours de sa vie. <\/span><br data-start=\"6155\" data-end=\"6158\" \/><span style=\"color: #339966;\">\u2714 Les \u00e9chouages massifs sur les plages sont souvent li\u00e9s \u00e0 des <strong data-start=\"6221\" data-end=\"6279\">conditions m\u00e9t\u00e9orologiques ou oc\u00e9aniques particuli\u00e8res<\/strong>.<\/span><\/p>\n<hr \/>\n<h2 id=\"-d\u2019o\u00f9-vient-la-couleur-viol\" data-start=\"93\" data-end=\"155\">D\u2019o\u00f9 vient la couleur violette de <em data-start=\"134\" data-end=\"153\">Janthina janthina<\/em> ?<\/h2>\n<p data-start=\"157\" data-end=\"429\">La couleur violette intense de <em data-start=\"188\" data-end=\"207\">Janthina janthina<\/em> <strong data-start=\"208\" data-end=\"257\">n\u2019est pas due \u00e0 un simple pigment de coquille<\/strong>, comme chez beaucoup de mollusques. Elle provient d\u2019un <strong data-start=\"313\" data-end=\"359\">m\u00e9lange de pigments organiques sp\u00e9cifiques<\/strong>, principalement des <strong data-start=\"380\" data-end=\"395\">porphyrines<\/strong>, produites par l\u2019animal lui-m\u00eame.<\/p>\n<hr data-start=\"431\" data-end=\"434\" \/>\n<h2 id=\"-une-couleur-produite-par-l\u2019\" data-start=\"436\" data-end=\"477\">Une couleur produite par l\u2019escargot<\/h2>\n<p data-start=\"479\" data-end=\"618\">Contrairement \u00e0 certaines esp\u00e8ces qui tirent leurs couleurs de leur alimentation, <em data-start=\"561\" data-end=\"580\">Janthina janthina<\/em> <strong data-start=\"581\" data-end=\"616\">synth\u00e9tise ses propres pigments<\/strong> :<\/p>\n<ul data-start=\"620\" data-end=\"873\">\n<li data-start=\"620\" data-end=\"768\">\n<p data-start=\"622\" data-end=\"768\">Les <strong data-start=\"626\" data-end=\"641\">porphyrines<\/strong> sont des mol\u00e9cules proches de celles impliqu\u00e9es dans l\u2019h\u00e9moglobine ou la chlorophylle (mais avec une fonction diff\u00e9rente ici).<\/p>\n<\/li>\n<li data-start=\"769\" data-end=\"873\">\n<p data-start=\"771\" data-end=\"801\">Ces pigments sont int\u00e9gr\u00e9s \u00e0 :<\/p>\n<ul data-start=\"804\" data-end=\"873\">\n<li data-start=\"804\" data-end=\"821\">\n<p data-start=\"806\" data-end=\"821\">la <strong data-start=\"809\" data-end=\"821\">coquille<\/strong><\/p>\n<\/li>\n<li data-start=\"824\" data-end=\"838\">\n<p data-start=\"826\" data-end=\"838\">le <strong data-start=\"829\" data-end=\"838\">mucus<\/strong><\/p>\n<\/li>\n<li data-start=\"841\" data-end=\"873\">\n<p data-start=\"843\" data-end=\"873\">et parfois aux <strong data-start=\"858\" data-end=\"873\">tissus mous<\/strong><\/p>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p data-start=\"875\" data-end=\"898\">C\u2019est ce qui explique :<\/p>\n<ul data-start=\"899\" data-end=\"1036\">\n<li data-start=\"899\" data-end=\"932\">\n<p data-start=\"901\" data-end=\"932\">la <strong data-start=\"904\" data-end=\"932\">teinte violette uniforme<\/strong><\/p>\n<\/li>\n<li data-start=\"933\" data-end=\"1036\">\n<p data-start=\"935\" data-end=\"1036\">le fait que la couleur <strong data-start=\"958\" data-end=\"994\">reste visible m\u00eame apr\u00e8s la mort<\/strong>, tant que la coquille n\u2019est pas d\u00e9grad\u00e9e.<\/p>\n<\/li>\n<\/ul>\n<hr data-start=\"1038\" data-end=\"1041\" \/>\n<h2 id=\"\u2600\ufe0f-un-r\u00f4le-fonctionnel-:-\" data-start=\"1043\" data-end=\"1095\">Un r\u00f4le fonctionnel : camouflage et protection<\/h2>\n<h3 id=\"-camouflage-invers\u00e9\" data-start=\"1097\" data-end=\"1122\">Camouflage invers\u00e9<\/h3>\n<p data-start=\"1123\" data-end=\"1226\"><em data-start=\"1123\" data-end=\"1142\">Janthina janthina<\/em> flotte <strong data-start=\"1150\" data-end=\"1174\">coquille vers le bas<\/strong>, l\u2019animal \u00e9tant suspendu sous son radeau de bulles.<\/p>\n<p data-start=\"1228\" data-end=\"1304\">La partie visible depuis le ciel est donc la <strong data-start=\"1276\" data-end=\"1302\">face ventrale violette<\/strong> :<\/p>\n<ul data-start=\"1305\" data-end=\"1457\">\n<li data-start=\"1305\" data-end=\"1383\">\n<p data-start=\"1307\" data-end=\"1383\">Vue du ciel : le violet sombre se confond avec la surface sombre de l\u2019oc\u00e9an.<\/p>\n<\/li>\n<li data-start=\"1384\" data-end=\"1457\">\n<p data-start=\"1386\" data-end=\"1457\">Vue depuis l\u2019eau : la surface claire est masqu\u00e9e par l\u2019\u00e9clat du soleil.<\/p>\n<\/li>\n<\/ul>\n<p data-start=\"1459\" data-end=\"1536\">C\u2019est un <strong data-start=\"1468\" data-end=\"1494\">contre-ombrage invers\u00e9<\/strong>, parfaitement adapt\u00e9 \u00e0 la vie en surface.<\/p>\n<hr data-start=\"1538\" data-end=\"1541\" \/>\n<h3 id=\"-protection-contre-les-uv\" data-start=\"1543\" data-end=\"1574\">Protection contre les UV<\/h3>\n<p data-start=\"1575\" data-end=\"1614\">Les porphyrines ont aussi la capacit\u00e9 :<\/p>\n<ul data-start=\"1615\" data-end=\"1715\">\n<li data-start=\"1615\" data-end=\"1649\">\n<p data-start=\"1617\" data-end=\"1649\">d\u2019<strong data-start=\"1619\" data-end=\"1649\">absorber une partie des UV<\/strong><\/p>\n<\/li>\n<li data-start=\"1650\" data-end=\"1715\">\n<p data-start=\"1652\" data-end=\"1715\">de prot\u00e9ger les tissus expos\u00e9s en permanence au soleil tropical<\/p>\n<\/li>\n<\/ul>\n<p data-start=\"1717\" data-end=\"1815\">Un avantage crucial pour un animal vivant <strong data-start=\"1762\" data-end=\"1783\">en pleine surface<\/strong>, sans possibilit\u00e9 de se cacher.<\/p>\n<hr data-start=\"1817\" data-end=\"1820\" \/>\n<h2 id=\"-et-l\u2019alimentation-dans-tout\" data-start=\"1822\" data-end=\"1860\">Et l\u2019alimentation dans tout \u00e7a ?<\/h2>\n<p data-start=\"1861\" data-end=\"2052\">M\u00eame si <em data-start=\"1869\" data-end=\"1888\">Janthina janthina<\/em> se nourrit de <strong data-start=\"1903\" data-end=\"1916\">physalies<\/strong> (elles-m\u00eames bleut\u00e9es\/violettes),<br data-start=\"1950\" data-end=\"1953\" \/><strong data-start=\"1956\" data-end=\"2012\">sa couleur ne vient pas directement de sa nourriture<\/strong>, contrairement \u00e0 certains nudibranches.<\/p>\n<p data-start=\"2054\" data-end=\"2216\">Cependant, il est probable que son r\u00e9gime riche en cnidaires ait <strong data-start=\"2119\" data-end=\"2144\">influenc\u00e9 l\u2019\u00e9volution<\/strong> de cette coloration, par s\u00e9lection naturelle (camouflage + protection).<\/p>\n<hr data-start=\"2218\" data-end=\"2221\" \/>\n<h2 id=\"-en-r\u00e9sum\u00e9-encadr\u00e9-p\u00e9dagog\" style=\"padding-left: 40px;\" data-start=\"2223\" data-end=\"2260\"><span style=\"color: #339966;\">En r\u00e9sum\u00e9<\/span><\/h2>\n<p style=\"padding-left: 40px;\" data-start=\"2262\" data-end=\"2469\"><span style=\"color: #339966;\">\u2714 Couleur due \u00e0 des <strong data-start=\"2282\" data-end=\"2309\">pigments porphyriniques<\/strong><\/span><br data-start=\"2309\" data-end=\"2312\" \/><span style=\"color: #339966;\">\u2714 Pigments <strong data-start=\"2323\" data-end=\"2350\">produits par l\u2019escargot<\/strong>, pas recycl\u00e9s depuis ses proies<\/span><br data-start=\"2382\" data-end=\"2385\" \/><span style=\"color: #339966;\">\u2714 R\u00f4le : <strong data-start=\"2394\" data-end=\"2424\">camouflage + protection UV<\/strong><\/span><br data-start=\"2424\" data-end=\"2427\" \/><span style=\"color: #339966;\">\u2714 Adaptation cl\u00e9 \u00e0 la vie <strong data-start=\"2453\" data-end=\"2469\">pleustonique<\/strong><\/span><\/p>\n<hr \/>\n<h2 id=\"-pourquoi-cet-\u00e9chouage-est-il\" data-start=\"277\" data-end=\"340\"><strong data-start=\"283\" data-end=\"340\">Pourquoi cet \u00e9chouage est-il inhabituel \u00e0 Hiengh\u00e8ne ?<\/strong><\/h2>\n<p data-start=\"342\" data-end=\"629\">Les \u00e9chouages de <em data-start=\"359\" data-end=\"378\">Janthina janthina<\/em> sont <strong data-start=\"384\" data-end=\"412\">par nature impr\u00e9visibles<\/strong>.<br data-start=\"413\" data-end=\"416\" \/>Cet escargot violet vit en pleine mer, <strong data-start=\"455\" data-end=\"482\">\u00e0 la surface de l\u2019oc\u00e9an<\/strong>, parfois tr\u00e8s loin des c\u00f4tes. Il ne se d\u00e9place pas activement : il d\u00e9rive au gr\u00e9 des vents et des courants, accroch\u00e9 \u00e0 son radeau de bulles d\u2019air.<\/p>\n<p data-start=\"631\" data-end=\"821\">En Nouvelle-Cal\u00e9donie, <strong data-start=\"654\" data-end=\"743\">aucune s\u00e9rie d\u2019observations scientifiques ne recense r\u00e9guli\u00e8rement ce type d\u2019\u00e9chouage<\/strong>, contrairement aux mammif\u00e8res marins. Cela signifie que ces \u00e9v\u00e9nements sont :<\/p>\n<ul data-start=\"822\" data-end=\"945\">\n<li data-start=\"822\" data-end=\"841\">\n<p data-start=\"824\" data-end=\"841\">soit <strong data-start=\"829\" data-end=\"838\">rares<\/strong>,<\/p>\n<\/li>\n<li data-start=\"842\" data-end=\"872\">\n<p data-start=\"844\" data-end=\"872\">soit <strong data-start=\"849\" data-end=\"869\">pass\u00e9s inaper\u00e7us<\/strong>,<\/p>\n<\/li>\n<li data-start=\"873\" data-end=\"945\">\n<p data-start=\"875\" data-end=\"945\">soit <strong data-start=\"880\" data-end=\"898\">non document\u00e9s<\/strong>, car concernant de petits organismes fragiles.<\/p>\n<\/li>\n<\/ul>\n<p data-start=\"947\" data-end=\"1135\">Le fait que des habitants n\u00e9s ici disent n\u2019en avoir jamais vu est donc <strong data-start=\"1018\" data-end=\"1042\">tout \u00e0 fait cr\u00e9dible<\/strong>.<br data-start=\"1043\" data-end=\"1046\" \/>Les \u00e9chouages de <em data-start=\"1063\" data-end=\"1073\">Janthina<\/em> n\u00e9cessitent une <strong data-start=\"1090\" data-end=\"1133\">combinaison tr\u00e8s sp\u00e9cifique de facteurs<\/strong> :<\/p>\n<ul data-start=\"1136\" data-end=\"1366\">\n<li data-start=\"1136\" data-end=\"1203\">\n<p data-start=\"1138\" data-end=\"1203\">pr\u00e9sence en mer de populations importantes d\u2019escargots violets,<\/p>\n<\/li>\n<li data-start=\"1204\" data-end=\"1256\">\n<p data-start=\"1206\" data-end=\"1256\">abondance de leurs proies (comme les physalies),<\/p>\n<\/li>\n<li data-start=\"1257\" data-end=\"1301\">\n<p data-start=\"1259\" data-end=\"1301\">vents persistants orient\u00e9s vers la c\u00f4te,<\/p>\n<\/li>\n<li data-start=\"1302\" data-end=\"1366\">\n<p data-start=\"1304\" data-end=\"1366\">courants favorables au transport du pleuston vers le littoral.<\/p>\n<\/li>\n<\/ul>\n<p data-start=\"1368\" data-end=\"1547\">Lorsque ces conditions sont r\u00e9unies, le ph\u00e9nom\u00e8ne peut \u00eatre <strong data-start=\"1428\" data-end=\"1445\">spectaculaire<\/strong>, mais aussi <strong data-start=\"1458\" data-end=\"1475\">tr\u00e8s ponctuel<\/strong>, parfois \u00e0 l\u2019\u00e9chelle de plusieurs d\u00e9cennies pour une m\u00eame zone c\u00f4ti\u00e8re.<\/p>\n<p data-start=\"1549\" data-end=\"1762\">Cet \u00e9chouage observ\u00e9 \u00e0 Koulnou\u00e9 est donc <strong data-start=\"1590\" data-end=\"1626\">un \u00e9v\u00e9nement naturel remarquable<\/strong>, r\u00e9v\u00e9lateur de la vie discr\u00e8te mais riche de la surface oc\u00e9anique, habituellement invisible aux yeux des plongeurs comme des riverains.<\/p>\n<hr \/>\n<h2 id=\"\u26a1ce-ph\u00e9nom\u00e8ne-existe-aille\" data-start=\"2123\" data-end=\"2213\"><strong data-start=\"2132\" data-end=\"2211\">Ce ph\u00e9nom\u00e8ne existe ailleurs dans le monde, m\u00eame dans des zones inattendues<\/strong><\/h2>\n<p data-start=\"2214\" data-end=\"2793\">Des archives naturalistes montrent que <em data-start=\"2253\" data-end=\"2272\">Janthina janthina<\/em> <strong data-start=\"2273\" data-end=\"2328\">peut \u00eatre observ\u00e9 \u00e9chou\u00e9 loin de son habitat normal<\/strong> quand les conditions oc\u00e9aniques le permettent \u2014 par exemple sur des plages du Pacifique, d\u2019Hawa\u00ef ou de Californie, souvent associ\u00e9 \u00e0 des photos de vastes accumulations apr\u00e8s des vents ou des courants particuliers.<br data-start=\"2579\" data-end=\"2582\" \/>Cela prouve qu\u2019une esp\u00e8ce <em data-start=\"2608\" data-end=\"2619\">pelagique<\/em> comme <em data-start=\"2626\" data-end=\"2639\">J. janthina<\/em> peut <strong data-start=\"2645\" data-end=\"2792\">appara\u00eetre sur les plages localement m\u00eame dans des zones o\u00f9 elle n\u2019est pas souvent not\u00e9e par les gens ou dans les enregistrements scientifiques<\/strong>.<\/p>\n<hr data-start=\"2795\" data-end=\"2798\" \/>\n<h3 id=\"-en-r\u00e9sum\u00e9\" style=\"padding-left: 80px;\" data-start=\"2800\" data-end=\"2816\"><span style=\"color: #339966;\">En r\u00e9sum\u00e9<\/span><\/h3>\n<ul>\n<li style=\"list-style-type: none;\">\n<ul>\n<li style=\"list-style-type: none;\">\n<ul data-start=\"2818\" data-end=\"3510\">\n<li data-start=\"2818\" data-end=\"2949\">\n<p data-start=\"2820\" data-end=\"2949\"><span style=\"color: #339966;\"><strong data-start=\"2820\" data-end=\"2827\">Non<\/strong>, il n\u2019existe pas de <strong data-start=\"2848\" data-end=\"2936\">registre scientifique connu d\u2019\u00e9chouages de <em data-start=\"2893\" data-end=\"2912\">Janthina janthina<\/em> en Nouvelle-Cal\u00e9donie<\/strong> \u00e0 ce jour.<\/span><\/p>\n<\/li>\n<li data-start=\"2950\" data-end=\"3222\">\n<p data-start=\"2952\" data-end=\"3222\"><span style=\"color: #339966;\"><strong data-start=\"2952\" data-end=\"2959\">Oui<\/strong>, il est tout \u00e0 fait possible \u2014 et m\u00eame logique biologiquement \u2014 que ces escargots <strong data-start=\"3042\" data-end=\"3102\">puissent s\u2019\u00e9chouer par centaines ou milliers \u00e0 Hiengh\u00e8ne<\/strong>, simplement parce que leurs populations flottent en pleine mer et que les vents\/courants les poussent vers le rivage.<\/span><\/p>\n<\/li>\n<li data-start=\"3223\" data-end=\"3510\">\n<p data-start=\"3225\" data-end=\"3510\"><span style=\"color: #339966;\">Le fait que m<strong data-start=\"3237\" data-end=\"3277\">es voisins n\u2019en aient jamais vu ici<\/strong> n\u2019est pas une preuve qu\u2019ils n\u2019y ont jamais \u00e9t\u00e9 : ces \u00e9v\u00e9nements sont <strong data-start=\"3347\" data-end=\"3427\">typiquement sporadiques et d\u00e9pendants des saisons, des vents et des courants<\/strong>, et souvent non document\u00e9s scientifiquement dans beaucoup de r\u00e9gions du Pacifique.<\/span><\/p>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<div class=\"entry-summary\">\nCette page est un compl\u00e9ment d&rsquo;information au sujet de l&rsquo;article de notre blog consacr\u00e9 \u00e0 Janthina l&rsquo; Escargot Violet des&hellip;\n<\/div>\n<div class=\"link-more\"><a href=\"https:\/\/www.babou-plongee.com\/blog\/janthina-janthina-le-petit-escargot-violet-des-oceans\/\" class=\"more-link\">Voir la suite<span class=\"screen-reader-text\"> &ldquo;Janthina janthina \u2013 Le Petit Escargot Violet des Oc\u00e9ans&rdquo;<\/span>&hellip;<\/a><\/div>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_seopress_robots_primary_cat":"","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","footnotes":""},"class_list":["post-4671","page","type-page","status-publish","hentry","entry"],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.babou-plongee.com\/blog\/wp-json\/wp\/v2\/pages\/4671"}],"collection":[{"href":"https:\/\/www.babou-plongee.com\/blog\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.babou-plongee.com\/blog\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.babou-plongee.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.babou-plongee.com\/blog\/wp-json\/wp\/v2\/comments?post=4671"}],"version-history":[{"count":3,"href":"https:\/\/www.babou-plongee.com\/blog\/wp-json\/wp\/v2\/pages\/4671\/revisions"}],"predecessor-version":[{"id":5053,"href":"https:\/\/www.babou-plongee.com\/blog\/wp-json\/wp\/v2\/pages\/4671\/revisions\/5053"}],"wp:attachment":[{"href":"https:\/\/www.babou-plongee.com\/blog\/wp-json\/wp\/v2\/media?parent=4671"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}