World news – Heads up: some sea slugs grow new bodies after being beheaded


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TOKYO – Scientists have discovered the ultimate case of regeneration: some beheaded sea slugs can have hearts and completely new bodies Regrowth.

This « miracle of nature, » reported on Monday in a biology journal, could ultimately help scientists better understand and tackle the regeneration of human tissue.

Biology researcher Sayaka Mitoh said she love studying Japanese sea snails because they are small, cute and weird. They can even briefly photosynthesize like a plant that gets food from the sun.

One day in the laboratory she saw something strange: a sea snail had beheaded itself and the head kept moving and living on. Then a few more did the same, according to a study in Current Biology.

PhD student and professor of aquatic ecology at Nara Women’s University, Yoichi Yusa, tried it herself and cut off the heads of 16 sea slugs. Six of the creatures began to regenerate, three were successful and survived. One of the three even lost and dragged his body twice. Two different species of Japanese sea slugs have performed this regeneration trick.

Other creatures may shed body parts if necessary, such as when some lizards drop their tails to escape a predator. This is a biological phenomenon called an autotomy.

« We think this is the most extreme case of autotomy, » said Yusa. « Some animals can autotomize their legs, limbs, or tails, but no other animal sheds their entire body. » Scientists had thought that such a relatively large animal – one of the species of sea slug – can grow up to 6 inches long – without one Heart couldn’t survive to pump blood and nutrients to the brain, said Canadian marine biologist Susan Anthony, who wasn’t part of the study.

But the same thing that makes this species spectacular is probably what you do helps pull the trick, said Anthony and Yusa.

When these sea slugs eat a certain type of algae, they can photosynthesize their food from sunlight and oxygen like a plant for about 10 days, Yusa said. What likely happens after the beheading is the head acting like a plant, he said. It turns green and gets its energy from oxygen and sunlight. The fact that it gets tiny helps, he said.

These species probably developed the feat to fight off parasites, said Mitoh and Yusa.

Humans might be able to do something useful from the marine animals to learn, said several scientists. What’s particularly intriguing is that these marine slugs are more complex than flatworms or other species known to regenerate, said Nicholas Curtis, a biology professor at Ave Maria University who wasn’t part of the study.

« It is of course a miracle of nature, but understanding the underlying molecular mechanisms could help us understand how our cells and tissues can be used to repair damage, « Curtis said in an email.

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