Some young sea spiders can regrow their hind limbs


No backside, no problem for some little sea spiders.

Creatures can regenerate Almost complete parts of her lower halves — including the muscles, genitals, and anus — or do without them, researchers report Jan. 23 Proceedings of the National Academy of Sciences.

The ability to regrow body parts is not very common, but some species do manage to get rid of it. Some sea slug heads It can make a completely new body (SN: 3/8/21). Sea spiders and some other arthropods—a group of invertebrates with an exoskeleton—can regrow parts of their legs. But the researchers believed that the new legs were how strong any arthropods were, perhaps because their tough exteriors somehow prevented them from regenerating other body parts.

  1. A micrograph of a young sea spider was amputated with the last quarter of its body, including its legs and anal tubercle.
  2. Micrograph of a juvenile sea spider after the first molt showing a short stub attached to a new body part at the hind end of the animal.
  3. Micrograph of an adult sea spider with new anal tubercle and legs beginning to take shape.
  4. Micrograph of a juvenile sea spider with its anal tubercle and fully repaired legs.

An unfortunate accident was the first to discover the evolutionary biologist George Brenes in those sea spiders (Pycnogonum litorale) It may be able to handle more complex repairs as well. He accidentally injured one small specimen he was working on in the lab with the tweezers. “It wasn’t dead, it was moving, so I kept it,” says Brenis of the University of Vienna. after several months, The sea spider has an extra leg Instead of a scar, he and evolutionary biologist Gerhard Schultz of Humboldt-University of Berlin reported in 2016 in physics.

In the new study, most of the 19 baby spiders recovered and rebuilt lost muscles and other parts of their lower half after amputation, although the regeneration wasn’t always perfect. Some juveniles wore six or seven legs instead of eight.

None of the four adults regenerated. This may be because adults no longer shed their skin as they grow, suggesting that regeneration and moulting are linked in some way, Brenes says. Two of the baby sea spiders also didn’t regenerate at all. The animals survived with only four legs and no anus. Instead of defecating, the pair squirted waste out of their mouths.

  1. Micrograph of a small sea spider with three small arms below its body.
  2. Micrograph of the same young sea spider without the three arms.
  3. Micrograph of a small four-legged sea spider.
  4. Micrograph of a small sea spider with four legs spread out.

The next step, Brenes says, is to see if other arthropods also regenerate more often than scientists thought, and how sea spiders do it. “I’d like to see how it works.”


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