By Marta Serafinko<\/p>\n
April 7 (Reuters) – A species of small fish has been observed by the thousands climbing a vertical waterfall 15 metres (50 feet) tall in the Democratic Republic of Congo in a behaviour that illustrates the surprising and ingenious ways animals can adapt to \u200cextreme environments.<\/p>\n
The researchers documented how this species of shellear fish, whose scientific name is Parakneria thysi, scales the Luvilombo Falls in the upper \u200cCongo Basin, a vast river system spanning Central Africa and home to the world’s second-largest rainforest. Researchers observed the fish ascending the vertical rock face during seasonal floods at the end of the \u200brainy season, typically in April and May.<\/p>\n
While this species can reach about 9.8 centimetres (3.9 inches) long, the researchers observed only small to medium-sized individuals – about 3.7 to 4.8 cm (1.5 to 1.9 inches) long – journeying up the falls.<\/p>\n
Observations suggest a fish may take nearly 10 hours to complete the slow and demanding climb to the top, moving in short bursts and resting frequently. Larger individuals of the species appeared to be too heavy for their fins to support the climb.<\/p>\n
“This discovery highlights the importance \u200cof maintaining the continuity of watercourses, particularly in the \u2060context of the Congo Basin, where studies on fish behaviour are virtually nonexistent,” said Pacifique Kiwele, a researcher in ichthyology and a member of the scientific staff at the Universit\u00e9 de Lubumbashi in the Democratic Republic of Congo who was the \u2060lead author of the study published in the journal Scientific Reports.<\/p>\n
“It prompts scientists to be even more vigilant in their observations, as anything is possible. Who would have believed it without being close enough to check, and document it with photographic and film material, that indeed some fish are able to climb waterfalls? It illustrates that there are \u200bwonders \u200bout there that surpass our imagination,” Kiwele said.<\/p>\n
Some other fish species are capable of scaling \u200bwaterfalls through various means but the researchers said this species \u200cis the first one documented in Africa.<\/p>\n
The researchers recorded the behaviour of this shellear fish on four occasions in 2018 and 2020, observing them moving up the rock face through what is called the splash zone – areas kept wet by spray rather than direct water flow.<\/p>\n
So how do they do it? The fish cling to wet rock surfaces using their pectoral fins, supported by pelvic fins and aided by tiny hook-like projections known as unculi, which help them grip surfaces, the researchers said. Then they push themselves upward by wiggling their bodies from side to side.<\/p>\n
Scaled to human size, it would be comparable to a person \u200cclimbing hundreds of metres (yards) vertically.<\/p>\n
The ascent is also risky. Some fish lose their grip when \u200bsudden jets of water hit them, knocking them off the rock face – particularly when they \u200bflip upside down to navigate overhanging sections.<\/p>\n
Given the volume of water at \u200bthe base of the falls, fish that fall are most likely able to start climbing again. However, those landing directly \u200conto rocks may not survive, the researchers said.<\/p>\n
So why do they \u200bdo it? The researchers said the fish \u200bmay climb upstream to find suitable living conditions and areas of the waterway with less competition and fewer predators.<\/p>\n
The researchers identified two major human threats to the species: illegal fishing using fine-mesh mosquito nets that can easily catch the fish, and water extraction for irrigation, which has \u200bin some years depleted the Luvilombo River.<\/p>\n
The discovery underscores how \u200clittle is known about fish behaviour in the Congo Basin, the researchers said.<\/p>\n
“It is quite possible that other fish species living in \u200brapid habitats … are capable of overcoming similar vertical obstacles,” Kiwele said, adding that researchers plan further fieldwork to confirm preliminary observations in \u200banother fish family.<\/p>\n
(Reporting by Marta Serafinko in Gdansk, Poland; Editing by Will Dunham)<\/p>\n","protected":false},"excerpt":{"rendered":"By Marta Serafinko April 7 (Reuters) – A species of small fish has been observed by the thousands…\n","protected":false},"author":2,"featured_media":592519,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[64,63,186967,68772,289301,289302,289303,10445,128,338],"class_list":{"0":"post-592518","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-wildlife","8":"tag-au","9":"tag-australia","10":"tag-congo-basin","11":"tag-democratic-republic-of-congo","12":"tag-fish-behaviour","13":"tag-fish-species","14":"tag-pacifique-kiwele","15":"tag-researchers","16":"tag-science","17":"tag-wildlife"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/592518","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=592518"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/592518\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/592519"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=592518"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=592518"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=592518"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}