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Figure 1. Photographs and drawings of a lagonomegopid spider (CNU-ARA-MA2016101) and an egg sac in Burmese amber CNU009432. (a) Habitus, dorsal view; (b) three-dimensional CT reconstruction, dorsal view, gray represents CNU-ARA-MA2016101, yellow represents egg sac; (c) schematic drawing of the dorsal habitus; (d) habitus, ventral view; (e) cross section of the egg bag, details in the boxes are enlarged and shown in other figures; (f) three-dimensional computed tomography reconstruction of the egg sac, dorsal view; (g) silk thread from the spider egg sac; (h) egg sac details, showing prelarvae and egg membranes (arrow); (i) egg sac details, showing prelarvae and egg membranes (arrows); (j) Lateral view of left tarsus I, showing trichobothria (asterisks). Scale bars represent 2mm (a, c, d), 0.5mm (e), 0.2mm (h, i, j) and 0.01mm (g); scale bars are absent in (b) and (f). Credit: DOI: 10.1098 / rspb.2021.1279
A trio of researchers from Capital Normal University in China have found evidence of a spider mother protecting her young in an amber sample dating to 99 million years ago. In their article published in Proceedings of the Royal Society B, Xiangbo Guo, Paul Selden and Dong Rend describe where the sample was found and what they learned about the spider it contains.
Many modern spider species have taken steps to ensure the survival of their offspring – females have been seen squatting to cover hatchlings, for example, and producing silk to tie and hold eggs tightly together. In this new effort, researchers found evidence of a Mid-Cretaceous mother spider exhibiting the same behavior.
Researchers found four pieces of amber that had been extracted from a mine in Myanmar that contained buried spiders. In one of the pieces, they found an adult female with some of her egg sac still intact under her body. The study of facial features showed that the spider was part of the extinct Lagonomegopidae family. The researchers also noted that the female was in a position very similar to that of modern female spiders who work to protect their eggs from predators. Closer examination showed that the female also used her own silk to tie the eggs together. Notably, some scientists have suggested that silk production in spiders began with attempts to tie the eggs together, and once it was established, they began to use it for other purposes, such as the construction of canvases.
The other three pieces of amber contained baby spiders and spider thread. One of them also had what appeared to be an arthropod leg and a wasp. The researchers suggest that each piece of amber is likely to contain related spiders, all of which have been identified as members of the Lagonomegopidae family. The researchers note that the adult female and groups of young spiders all had large eyes, suggesting they were free-range hunters rather than website builders. They also note that one of the pieces contains pieces of material suggesting that the spiders had recently left a nest.
Spiders use pre-stretched silk to lift their prey from the ground
Xiangbo Guo et al, Maternal care in mid-Cretaceous lagoonomegopid spiders, Proceedings of the Royal Society B: Biological Sciences (2021). DOI: 10.1098 / rspb.2021.1279
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Quote: Former mother spider preserved in amber protecting her young (2021, September 15) retrieved September 15, 2021 from https://phys.org/news/2021-09-ancient-spider-mom-amber-young.html
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