Ancient Spider’s Web Preserved In Amber

Fossils in amber provide a window for palaeontologists into ancient ecoystems.

An amateur fossil hunter looking for dinosaur fossils along the Sussex coast (England), has found a 140 million-year-old piece of amber (fossilised tree resin), which contains the remains of a spider’s web.  This discovery is being claimed by scientists as the oldest spider’s web evidence ever found in the fossil record.

Spider Fossil

The amber and the tiny, tangled fragments of web have been dated to the Early Cretaceous (Berriasian/Valanginian faunal stages), a time when the Earth was much warmer and dinosaurs dominated the Earth.  The web’s structure seems similar to those webs woven by modern orb spiders.  Orb spiders weave a spiral of silk, many with sticky droplets on them to help trap insects.

The amber, which was found on a Sussex beach (near Bexhill) was handed over to palaeobiologist Professor Martin Brasier who analysed the contents of the amber nodule.  His findings are reported in the Journal of the Geological Society.  The minute threads of spider silk are about 1 millimetre long and suspended in the amber nodule along with bits of burnt tree sap, insect droppings, microbes and fossilised vegetable matter.  The amber nodule was found by amateur fossil hunter Jamie Hiscocks.

Prof. Brasier, a member of the faculty at the University of Oxford commentated:

“This amber is very rare. It comes from the very base of the Cretaceous period, which makes it one of the oldest ambers anywhere to have inclusions in it.”

Earliest Evidence of Actinobacteria

Professor Brasier and his colleagues have also found the earliest evidence of Actinobacteria a tiny group of organisms that break down wood and resins into soil particles, potentially rewriting the history of soil evolution.  An examination of the threads contained in the amber indicate that they were spun by spiders closely related to modern day Orb spiders, or Garden spiders.  Spiders are members of the Phylum Arthropoda, the largest phylum of animals.  Fossils of spiders are extremely rare in the fossil record, although palaeontologists believe that spiders evolved during the Devonian (410-355 million-years-ago).

Professor Brasier stated:

“We actually have the sticky droplets preserved within the amber.  These turn out to be the earliest webs that have ever been incorporated in the fossil record to our knowledge.  You can match the details of the spider’s web with the spider’s web in my garden.”

Spider Silk Trapped in Sticky Resin

The spider silk became trapped in sticky resin (most probably from a conifer), the resin may have been produced by the tree to help heal a wound in the tree bark, perhaps as a response to fire damage.  There is evidence of a fire event, this is indicated by the burnt sap contained within the amber nodule.

The arrow in the diagrams released to the media is pointing at a tiny strand of spider silk.  These remains were identified by Professor Brasier and his team when they viewed the amber as different sections and studied these slices using microscopic imaging, a technique known as confocal microscopy.  The large, dark blobs are pieces of burnt tree sap.

Experiments using modern cherry trees have demonstrated that very similar threads can be obtained by trapping modern spider webs in resin.

More Amber Nodules to Study

Just a tiny proportion of the deposits have so far been examined, and Professor Brasier and his colleagues believe that amber nodules such as this one have the potential to yield many more exciting finds, largely due to the development of increasingly powerful imaging techniques.

He said:

“It is a very exciting time to be a palaeontologist, because of all these wonderful techniques being developed.  We are able to view things and see detail in ways that we’ve never been able to before.”

The discovery suggests that orb web spinning spiders existed far earlier than had been previously thought, at a time before flowering plants appeared on the planet and triggered an explosion in flying insects.  The Bexhill site has revealed a number of other finds, including charcoal indicating that forest fires were common in the area during this time in Earth’s history.

Amber from the North Sea

The amber deposit, which is hidden beneath the tide for much of the time, is also believed to be the first significant amber deposit in Britain.  Most famous amber deposits have been found in France, Germany, the Caribbean and Lebanon.  A lot of jewellery is made from Baltic amber, this dates from the Palaeogene period, so it is approximately 90 million years younger than the Bexhill find.  Occasionally, pieces of Baltic amber are found on the Norfolk coast, having floated across the North Sea.  Amber, as it is a natural substance filled with air spaces, is buoyant and can float in sea water.

Despite the intense interest in the newly discovered spider silk, questions have been asked by members of the press about whether dinosaur DNA could ever be extracted from amber, thus leading to a real-life Jurassic Park.  For the time being let us marvel at the miraculous way in which this ancient evidence of a spider’s activity has been preserved.

For replicas of iconic invertebrates from the fossil record: Replicas of Fossil Animals.