If you feed a tiny flatworm plenty of food, its single body will quickly elongate as new heads emerge one after another.<\/p>\n
Within a few days, a single worm develops into a chain of four or five interconnected clones, temporarily linked together.<\/p>\n
However, this transformation is not the result of a new genetic mutation. It occurs when the worm's normal reproductive cycles overlap.<\/p>\n
Essentially, the worm goes into a feeding frenzy, starting to grow the next clone even before the last worm it created has separated.<\/p>\n
Scientists at the University of Warsaw in Poland have discovered that an abundance of food can trigger this striking transformation in four microscopic species of flatworms. Stenostomum<\/em> , living mainly in fresh water.<\/p>\n This study is available as a preprint on bioRxiv and has not yet been peer-reviewed.<\/p>\n Flatworms are soft-bodied, backboneless animals that often reproduce without mating, producing offspring that are genetically identical to themselves.<\/p>\n Typically, a flatworm develops a new head and corresponding body part within its existing body. After the new part has completed its development, it typically detaches and continues to live independently.<\/p>\n This method of asexual reproduction is known as paratomy and Stenostomum<\/em> It involves a flurry of gene activity that leads to a growth spurt and much-needed organization of the body's axis.<\/p>\n Flatworms are also known for their extraordinary developmental flexibility. In laboratory conditions, some species can be induced to grow heads shaped like those of other species without any changes to their DNA, or they can naturally regrow a head at each end.<\/p>\n In new experiments, food abundance altered the timing of reproduction. The worms grew so rapidly that the next reproductive cycle began even before the previous one was complete.<\/p>\n Subsequently, several developing sections of the clone remained connected, forming a temporary chain with multiple heads.<\/p>\n \u00ab"From the very beginning, we suspected that food might be the cause of the chain," Ludwik Gasiorowski, a zoologist at the University of Warsaw, told ScienceAlert.<\/p>\n \u00abHowever, I personally expected that this process would be triggered by the quality of food (that is, the types of prey), rather than its quantity.\u00bb.<\/p>\n Initially, the team proposed six types of microscopic prey for six species of fungi in the genus Stenostomum<\/em> .<\/p>\n Four species grew and reproduced stably when fed a single-celled freshwater organism containing green algae.<\/p>\n The researchers then varied the amount of this prey, and as food availability increased, prey chain formation increased significantly.<\/p>\n \u00ab"What surprised me most was how reliable and reproducible this effect was," Gasiorowski said.<\/p>\n \u00ab"If we want to get worms that are chained together, we just put them in a known high concentration of a certain prey for three days, and we will always see these chains.".<\/p>\n The abundance of food prompted the worms to breed Stenostomum<\/em> switch from normal asexual reproduction (left) to the formation of chains of linked clones (right). (G\u0105siorowski et al., bioRxiv, 2026)<\/p>\n<\/figcaption><\/figure>\n When the worms ingested the green cells of their prey, their digestive systems turned bright green and their bodies rapidly elongated.<\/p>\n \u00ab"After about two days, the first of the new heads becomes visible," Gasiorowski explained.<\/p>\n Initially, the developing head appears as two clear spots in the middle of the worm, as the developing brain pushes the darker intestinal tissue inward.<\/p>\n Then additional heads begin to appear along the lengthening body, which can be seen in the image below.<\/p>\n About four days after feeding begins, the longest chains contain four or five zooids connected tail-to-head.<\/p>\n Image of a chain Stenostomum brevipharyngium<\/em> , obtained using confocal microscopy, shows the varying degrees of development of individual heads (arrows). Scale bar: 100 \u00b5m (Comparative Invertebrate Zoology Group, University of Warsaw\/CC BY-NC 4.0)<\/p>\n<\/figcaption><\/figure>\n These chains are not permanent. After the oldest developing head has formed, the worms divide into smaller chains or individual worms. If there is enough food, they grow, form chains, and divide again.<\/p>\n The extra feeding speeds up the worm's growth in length, but it still takes about four days for a new head to form\u2014thus, the worm is large enough to begin another reproductive cycle before completing the first.<\/p>\n Researchers call these chain-like structures "paracolonies" because they resemble animals that form clonal colonies but eventually disintegrate.<\/p>\n The team also tested whether being in the chain provided any direct benefit to the worms. They found no evidence that the connected regions shared the digestive work.<\/p>\n However, in experiments, chains of worms of the same species Stenostomum<\/em> were less likely to be chosen by a predator than single worms, although this tendency was not observed in the case of the other species.<\/p>\n This is not necessarily due to the fact that the chains Stenostomum<\/em> possessed great intelligence to somehow outsmart the predators.<\/p>\n Gasiorowski noted that even if an advantage exists, it may be a result of larger body size (and therefore more cilia to propel the worms through water), rather than having multiple connected heads.<\/p>\n \u00ab"We still know very little about the ecology of these microscopic invertebrates\u2014we don't even know who their main predators are in the wild, which limits our ability to study some of the ecological mechanisms," he said.<\/p>\n \u00ab"Even if worms are selected for their ability to increase their body size, chain formation remains an accidental by-product of development.".<\/p>\n Although for Stenostomum<\/em> This is only a temporary phase, and some related flatworms are known to form permanent chains, suggesting that this form may be beneficial to them.<\/p>\n For example, Catenula lemnae<\/em> can form chains containing more than 15 connected sections, while in another related species of flatworms up to 50 such sections have been observed.<\/p>\n Time chain at Stenostomum brevipharyngium<\/em> (top) and a constant chain at Catenula lemnae<\/em> (bottom). Arrows indicate the heads of successive zooids. Scale bars: 100 \u00b5m (Comparative Invertebrate Zoology Group, University of Warsaw\/CC BY-NC 4.0)<\/p>\n<\/figcaption><\/figure>\n However, Gasiorovsky's team failed to remain viable. C. lemnae<\/em> in laboratory conditions, so they do not know whether the reproductive strategy is C. lemnae<\/em> a more established version of food chains Stenostomum<\/em> .<\/p>\n See also:<\/strong> Newly discovered microbe has evolved into a cannibalistic 'supergiant'\u00ab<\/strong><\/p>\n \u00ab"We cannot directly test whether the alternation of asexual reproduction and chain formation follows the same logic as in Stenostomum<\/em> \u00bb"," Gasiorowski said, although given their close relationship, "it seems plausible that the chains Catenula<\/em> developed from conditions similar to those we observe in Stenostomum<\/em> \u00bb.<\/p>\n If we know so little about the aquatic worlds inhabited by these worms, these questions remain intriguing and worthy of attention for now.<\/p>\n The results of the study are available on the preprint server bioRxiv.<\/p>\n ScienceAlert articles are written, fact-checked, and edited by humans; they are never generated by artificial intelligence. Don't miss a single article; subscribe here.<\/p>\n Scientists have discovered a hidden fault beneath New Jersey that could cause the 2024 earthquake.<\/p>\n<\/li>\n Stunning footage shows dolphins hunting using shells off Australia's east coast \u2013 and possibly passing on the skill to others.<\/p>\n<\/li>\n Test Yourself: This Week's Microscope Riddle<\/p>\n<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":" If you feed a tiny flatworm plenty of food, its single body will quickly elongate as new heads emerge one after another. Within a few days, a single worm\u2026<\/p>","protected":false},"author":1,"featured_media":20500,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-20499","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","hvn-theme-has-thumbnail"],"_links":{"self":[{"href":"https:\/\/imgist.ru\/en\/wp-json\/wp\/v2\/posts\/20499","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/imgist.ru\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/imgist.ru\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/imgist.ru\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/imgist.ru\/en\/wp-json\/wp\/v2\/comments?post=20499"}],"version-history":[{"count":4,"href":"https:\/\/imgist.ru\/en\/wp-json\/wp\/v2\/posts\/20499\/revisions"}],"predecessor-version":[{"id":162032,"href":"https:\/\/imgist.ru\/en\/wp-json\/wp\/v2\/posts\/20499\/revisions\/162032"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/imgist.ru\/en\/wp-json\/wp\/v2\/media\/20500"}],"wp:attachment":[{"href":"https:\/\/imgist.ru\/en\/wp-json\/wp\/v2\/media?parent=20499"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/imgist.ru\/en\/wp-json\/wp\/v2\/categories?post=20499"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/imgist.ru\/en\/wp-json\/wp\/v2\/tags?post=20499"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}} Related news<\/h3>\n
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