99 Million-Year-Old Fossil of Spider Mom Protecting Its Young Preserved Found in Amber

A team of researchers from the Capital Normal University in China has found evidence of a mother spider protecting its hatchlings encased in amber that dated back to 99 million years ago.

Phys.org reported that the spider fossil was in a stance that resembles modern spider species when protecting their offspring. For example, some spider moms would produce silk to hold their eggs closely. Researchers said that the spider was a member of the Lagonomegopidae family that has long been extinct.

How Do Spider Moms Protect Their Eggs

An article on the website Northern Wetlands said that spider moms protect their eggs by wrapping them in silk that forms into an egg sac by spinning a few spider threads that barely hold the egg. Since egg sacs of different species differ in color and shape, they are easily identified.

However, finishing an egg sac is where most of spider moms' parental duties end. Although, there are also some spider species where making egg sacs is just the start of their parenting journey.

Spider moms guard their eggs and spiderlings against predators and parasites. The egg sac is a symbol of their maternal commitment because it is tastier than other insect egg sacs. Some wasps become parasites of spider egg sacs wherein once spiderlings leave their silk egg wrappings, wasps lay their own eggs inside it, and wasp larvae would munch up all the spider eggs once it hatched.

Some spider species would guard their hatchlings after hatching, but some would carry them on their backs. This will give the spider moms the freedom to hunt while still caring for their hatchlings and helping them get out of their sacs.

Spider Mom Protecting Her Offspring Preserved in Amber

Going back some 99 million years ago, the protective instinct of a spider mom was well preserved in Burmese amber. According to Phys.org, researchers found four chunks of amber extracted from a mine in Myanmar that encased some extinct species of spiders. One of the fossils features a spider mom who used its silk to tie the eggs in a protective position.

Researchers noted that the egg sac is broken inside the amber but can be seen under the body of the female spider. They also noticed baby spiders and spider thread in the other three chunks of amber. Also, one of them had an undefined arthropod leg and perhaps a cockroach or a wasp.

Daily Mail reported that one of the amber chunks contained two dozens of prelarvae and egg membranes still wrapped in the egg sac. Meanwhile, the other one has about 26 baby spiders, and the third one has 34 spiderlings.

Furthermore, researchers assume that the spiderlings are all siblings from the female spider encased in the amber because they are the same size. Using a CT scan, they identified two large eyes in front of the female spider's head and revealed 3D details of the spiderlings.

Researchers hypothesize that the hatchlings likely died after emerging from their eggs, while the legs and appendages preserved beside them were most likely from their mother.

The full findings of their study, titled "Maternal Care in Mid-Cretaceous Lagonomegopid Spiders," were published in Proceedings of the Royal Society B.

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