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Their striped or mottled shells<\/a> become dark brown, matching wet tree bark, helping them stay hidden from hungry birds until the surface dries again.<\/p>\n Hidden in plain sight<\/p>\n Scientists recently discovered how this unusual form of camouflage<\/a> works. The two species involved are Hypselostyla camelopardalis from the Philippines and Reinia variegata from Japan. <\/p>\n Although they live far apart and are only distantly related, both developed the same ability on their own through evolution<\/a>.<\/p>\n The finding challenges a long-held belief that snail shell colors and patterns remain fixed throughout the animal\u2019s life.<\/p>\n Instead, these shells can change their appearance within moments as moisture levels rise and fall.<\/p>\n \u201cThe Philippine Hypselostyla camelopardalis and the Japanese Reinia variegata are tree-dwelling snails that both exhibit a reversible form of \u2018hydrochromism,\u2019\u201d explained Taro Yoshimura, a researcher at the University of Tokyo<\/a>.<\/p>\n He added, \u201cTheir mottled shell patterns completely disappear upon wetting, causing the shell to darken uniformly, and then rapidly reappear as they dry.\u201d<\/p>\n Unchanging in color<\/p>\n The secret isn\u2019t a chemical reaction or a special pigment. It comes from the shell\u2019s structure.<\/p>\n Researchers found that the shell\u2019s outermost protective layer, known as the periostracum, has countless tiny sponge-like pores.<\/p>\n When moisture fills those pores, the shell\u2019s appearance changes because light passes through the shell differently.<\/p>\n \u201cWe now understand the physical mechanism driving this phenomenon: a process known as refractive index matching. The two-layered structure of the outermost organic membrane of the shell (called the periostracum) has spongelike nano- to microscale voids that absorb moisture,\u201d explained Yoshimura.<\/p>\n He noted \u201cThe water-filled pores suppress light scattering, allowing light to pass through the membrane and reveal the dark pigments of the crystalline shell layer below.\u201d <\/p>\n An old mystery<\/p>\n To figure out exactly what was happening, they examined preserved snail shells from the University of Tokyo Museum collection using several advanced imaging techniques.<\/p>\n A field-emission scanning electron microscope revealed the shell\u2019s two-layer design.<\/p>\n A confocal laser scanning microscope captured the shell\u2019s rapid hydration during repeated wetting and drying tests. The team also measured how much light passed through the shell.<\/p>\n Light transmittance jumped from roughly 37% when the shell was dry to around 85% after it became wet.<\/p>\n For many years, scientists believed that shell patterns were permanent because they were created by pigments locked inside mineral layers during shell growth. <\/p>\n This study shows that appearance can also change because of the shell\u2019s physical structure interacting with water in the environment.<\/p>\n \u201cConventionally, molluscan shell coloration and patterning have been considered static features, strictly determined by pigments embedded within the calcified crystalline layers,\u201d said Yoshimura.<\/p>\n He added, \u201cOur study fundamentally challenges this established paradigm, altering their appearance in real time based on ambient humidity.\u201d<\/p>\n A shared path<\/p>\n He also noted that \u201cwitnessing natural selection<\/a> can drive entirely different organisms toward the exact same elegant evolutionary solution was an incredibly exciting discovery.\u201d<\/p>\n The fact that two distant species independently evolved also highlights a common pattern in evolution.<\/p>\n When different animals face similar challenges, they sometimes arrive at remarkably similar answers despite having separate evolutionary histories.<\/p>\n Inspiring new materials<\/p>\n This may hold value beyond biology<\/a>. Materials that respond to humidity could be useful in homes, environmental monitoring, medicine, and manufacturing.<\/p>\n Engineers have long looked to nature for ideas, and this snail shell offers another example of how simple physical<\/a> structures can perform complex tasks.<\/p>\n \u201cThe greatest advantage of the snails\u2019 mechanism is that it alters their optical properties autonomously in response to ambient moisture, without any external power source,\u201d said Yoshimura. <\/p>\n \u201cMy ultimate hope is to bridge the gap between evolutionary biology and material science, translating nature\u2019s zero-energy physical tricks into the practical development and commercialization of next-generation smart materials,\u201d he concluded.<\/p>\n This study was published in EurekAlert.<\/a><\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"While octopuses and cuttlefish are famous for changing their appearance, a pair of tiny tree snails has been…\n","protected":false},"author":2,"featured_media":541088,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[61,60,82,263],"class_list":["post-541087","post","type-post","status-publish","format-standard","has-post-thumbnail","category-wildlife","tag-ie","tag-ireland","tag-science","tag-wildlife"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/541087","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=541087"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/541087\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/541088"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=541087"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=541087"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=541087"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"Photos](\"https:\/\/www.newsbeep.com\/ie\/wp-content\/uploads\/2026\/07\/snails_wet-dry-shells_Hypselostyla-camelopardalis_Reinia-variegata_1s.webp\")
<\/a>Photos of the disappearing patterns on the (A) Hypselostyla camelopardalis and (B) Reinia variegata, when going from dry to wet. The scale bar in the bottom right is 10 millimeters. Credit: Yoshimura & Sasaki (2026). Click image to enlarge.Seeing in a new way<\/p>\n