Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Science https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ These snails cut off their own heads when they want a new body

These snails cut off their own heads when they want a new body



The head (left) and body (right) of a regenerative, photosynthetic sea snail.

The head (left) and body (right) of a regenerative, photosynthetic sea snail.
Image: Sayaka Mitoh

They look like open pea pods with a shiny sheen, sea snails Elysia cf. the margin and Elysia atroviridis aren’t they your average gastropods. First, they are members of the sacoglossa, a the snail pile, known for taking seaweed from seaweed and integrating it the chloroplasts of these algae in their own cells, which allows them to receive energy from sunlight. these two species of snails are also capable of extreme regeneration; they I can they cut off their heads and grow entirely new bodies.

New research published today in Current Biology describes this incredible feat of autotomy or self-amputation. (It is worth mentioning that bodies do not generate new heads.) The discovery was made in the laboratory of Yoichi Yusa at Nara Women’s University in Japan, which cultures sea ​​snails from eggs to adulthood through the generations to better find out these slimy creatures.

Sayaka Mitoh, a university biologist and lead author of a recent article, stumbled upon the well-meaning self-dissection of snails when he came across a man in the lab whose head was no longer connected to his pickled body. . But his head was still moving.

“We didn’t expect them to do such an unusual autotomy,” Mitoch said in an email. “This find was a complete coincidence.”

Once the team found a self-torn man, they began investigating why and exactly how the fracture occurred. These observations include attempts to induce self-glazing, mimicking the kind of fleeting slips that a marine predator would make on a snail in the wild (perhaps, they suggested, the separation of the slugs from his body was similar to that of a fighter pilot using a discharge seat).

Researchers they tied a nylon cord around the place where the snail’s head met his body, where the snail seemed to be prone to splitting the body. They did this lightly enough, more like an overly tight tie than a suffocation – but snails don’t have a respiratory system like vertebrates, so there aren’t any big ones..

Although the true nature of autotomy remains unknown, the team was able to challenge autonomy in all but one snail. within a day. In the article, the Mitoh team suggests that autotomy may occur in the wild Elysia atroviridis because the snail is regularly burdened with planktonic parasites – perhaps leaving a parasite-ridden body to raise a new one is the easiest way to deal with the infection. The researchers found that snails can spend days without their hearts (located in body just below the plane of fracture), and, for a couple weeks the new bodies were almost full size. In the newspaper, the team claims that snails can pass without their bodies, surviving purely on them. photosynthetic possibilities.

“As long as they live a few days without a heart, it may sound impossible from our human point of view, these animals actually breathe through their skin and completely lack gills,” he said. Ellis Laetz, sea snail photosynthesis expert from the University of Groningen, The Netherlands who is not related to the new study. “I’m not surprised that they can last a week without a heart to pump oxygen hemolymph (like invertebrate blood) around their bodies while regenerating a new one.”

Laetz said in an email that the idea of ​​photosynthesis as a ration seems less likely because many of the mechanisms of kleptoplasty (this unique ability of kleptoplasty) taking chloroplasts from algae and use to harness them solar energy) are located in the body, not in the head.

“Chloroplasts are stored in the snail’s digestive gland, which is highly branched and is found mainly in the body of most succulent species. When a snail automates its body, it releases most of its chloroplasts and therefore most of the energy it could get from these chloroplasts, ”said Laetz. “I think the snail is more likely to nourish regeneration by feeding directly after automating its body, as the authors note.”

Much more research needs to be done to better understand how these spinning little snails escape their existence without the help (or hindrance) of most of their body shape. tnew observations show that there are many more questions to ask theme animals.

“We want to study whether other species of sacclos have this ability, to study the evolutionary model and the process of such extreme autotomy and regeneration,” Mitoch said. “The function of autotomy is also worth exploring. Moreover, we will further investigate the mechanisms underlying this phenomenon at the tissue and cellular levels. “

They may not have charisma on a corgi ” giraffe or on bizarre platypus DNAbut photosynthetic, self-circumcision sea ​​snails within the sacoglossa deserve all the same amount of attention. Headless bodies will continue to be studied, and disembodied heads even more so.

“Observations such as those presented in this article underscore the need for basic research on all branches of the tree of life,” Laetz said. “You never know when an animal as harmless as a sea snail has an ability that can lead to advances in applied research.”


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