A nurse shark with vivid orange skin has been documented off Costa Rica\u2019s Caribbean coast. The first recorded case of xanthism (also known as xanthochromism) in cartilaginous fishes in the Caribbean was the first in this species. The shark, measuring roughly two meters (over six feet), was captured during a sport fishing trip near Tortuguero National Park at a depth of 37 meters and later released, according to a new paper summarizing the sighting and photographs shared from the trip.<\/p>\n
Researchers identify<\/a> the unusual coloration as xanthism, a pigmentation anomaly characterized by excess yellow or golden tones caused by a lack of red pigmentation. Nurse sharks (Ginglymostoma cirratum) typically display brown skin that helps them blend with the seabed, so the bright orange hue made this individual stand out dramatically from the species\u2019 usual appearance.<\/p>\n The shark also had white eyes \u201cwith no visible irises\u201d, a detail the authors suggest points to a rare case of albino-xanthochromism rather than xanthism alone. Until now, there had been no documentation of partial or full xanthism in cartilaginous fishes in the Caribbean or along Costa Rica\u2019s Pacific coast. The Federal University of Rio Grande-linked team notes that the finding expands what is known about pigment variation in the region\u2019s shark populations<\/a> and raises questions about underlying genetic diversity.<\/p>\n What xanthism is, and why this shark matters<\/p>\n Xanthism has been confirmed in only a handful of animals across the tree of life. It has produced striking yellow morphs among freshwater fish, and birds such as parrots and canaries have been seen with golden feathers. There have also been occasional reports of unusually yellow snakes<\/a> and lizards. The opposite condition, axanthism, involves a lack of yellow pigment.<\/p>\n The cause of xanthochromism is considered primarily genetic, akin to melanism or leucism, but other influences cannot be ruled out. As the authors emphasize, \u201cFactors such as inbreeding, environmental stress, elevated temperatures, and hormonal imbalances may also influence pigmentation,\u201d explain the authors. Diet has also been cited as a potential contributor in some animals, though the paper underscores that genetic pathways are central to producing the orange phenotype.<\/p>\n Nurse sharks are mid-level predators that feed on small fish, mollusks, and crustaceans. They are unusual among sharks<\/a> in that, unlike species that must swim constantly to breathe, they use a buccal pump that allows them to ventilate while stationary.\u00a0<\/p>\n Bright coloration or white eyes associated with albinism can make animals more visible to predators, leading researchers to argue that xanthism lowers survival<\/a> rates in the wild. In this case, however, the individual\u2019s size suggests it had already reached adulthood: \u201cit appears that this unusual pigmentation did not affect its survival.\u201d<\/p>\n Next questions for Caribbean shark genetics<\/p>\n The discovery highlights a previously unreported pigmentation pathway in Caribbean cartilaginous fishes. While the condition is usually tied to mutation, the team notes that environmental context could modulate expression. \u201cFurther research is needed to explore potential genetic or environmental factors influencing this rare pigmentation anomaly in sharks,\u201d the researchers said.<\/p>\n Given how infrequently xanthism is observed across animals, the Costa Rica case adds a rare datapoint from a region where the condition had not been recorded. For field biologists documenting future sightings, especially with clear photographs of skin and eyes, could help determine how widespread such pigment anomalies<\/a> are and whether regional environmental pressures play any role in their emergence.<\/p>\n","protected":false},"excerpt":{"rendered":"A nurse shark with vivid orange skin has been documented off Costa Rica\u2019s Caribbean coast. The first recorded…\n","protected":false},"author":2,"featured_media":88519,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[20233,64,63,10404,13453,336,22938,2270,66016,5036,66017,128,66018,2269,20198,338,66019],"class_list":["post-88518","post","type-post","status-publish","format-standard","has-post-thumbnail","category-wildlife","tag-animal","tag-au","tag-australia","tag-caribbean","tag-costa-rica","tag-genetics","tag-marine-biology","tag-nature","tag-nurse-shark","tag-ocean","tag-orange-shark","tag-science","tag-sea-creatures","tag-shark","tag-skin","tag-wildlife","tag-xanthism"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/88518","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=88518"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/88518\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/88519"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=88518"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=88518"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=88518"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}