No back, no problem for some juvenile sea spiders.
organisms can regenerate almost complete lower half – including muscles, reproductive organs and anus – or without them, researchers report Jan. 23 Proceedings of the National Academy of Sciences.
The ability to regrow body parts is uncommon, but some species manage to do it.some sea cucumber heads Can make a whole new body (Serial number: 21/3/8). Sea spiders and some other arthropods—a group of invertebrates with exoskeletons—can regenerate parts of their legs. But the researchers think the new legs are the limit of any arthropod’s strength, perhaps because the hard exterior somehow prevents them from regenerating other body parts.
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After the first molt, the anal tubercle and the two legs begin to re-form, appearing as short stumps attached to the new body part (center, bottom) at the animal’s rear end. G. Brunnis and others/Member of the National Academy of Sciences 2023 -
After the sea spider sheds its exoskeleton for the second time, its anal tubercle and legs are taking shape. G. Brunnis and others/Member of the National Academy of Sciences 2023 -
After the third molt, the animal appeared to be back to normal again. G. Brunnis and others/Member of the National Academy of Sciences 2023
An unfortunate event first led evolutionary biologist Georg Brenneis to discover sea spiders (Pycnogonum litorale) Might be able to handle more complex repairs too. He accidentally injures a young specimen with tweezers in the lab. “It’s not dead, it’s moving, so I just left it,” says Brenneis of the University of Vienna. a few months later, The sea spider has an extra leg He and evolutionary biologist Gerhard Scholtz of the Humboldt University of Berlin met in 2016 in natural science.
In the new study, most of the 19 young spiders recovered and regenerated missing muscles and other parts of their lower bodies after amputation, though the regeneration wasn’t always perfect. Some juveniles have six or seven legs instead of eight.
None of the four adults were reborn. This may be because adult animals no longer molt as they grow, suggesting a link between regeneration and molting, Brenneis said. The two juvenile sea spiders also did not regenerate at all. The animals survived with only four legs and no anus. Instead of defecating, the couple spit waste out of their mouths.
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This young sea spider has three small stumps (middle, bottom) which, if left untreated, would develop into the animal’s last two body parts, which include the two pairs of legs and its anal tubercle. G. Brunnis and others/Member of the National Academy of Sciences 2023 -
This photo shows the same sea spider, but with the rear of its developed body — the three stumps in the previous photo — removed. G. Brunnis and others/Member of the National Academy of Sciences 2023 -
After the first molt, there is no sign of regrowth. This animal has four legs instead of eight. G. Brunnis and others/Member of the National Academy of Sciences 2023 -
After the third molt, the animal still had only four legs and no anal tubercle. Because it doesn’t have an anus, it spits out excrement through its mouth. G. Brunnis and others/Member of the National Academy of Sciences 2023
The next step, Brenneis said, is to figure out whether other arthropods also regenerate faster than scientists thought, and how sea spiders do it. “I want to see how it works.”
