Charles Darwin’s On the Origin of Species was a groundbreaking work resulting from decades of scientific observation and careful thought. Exactly 150 years after its publication on November 24, 2009 a paper was presented on a new species of spider named in his honor: the Darwin’s bark spider (Caerostris darwini). Have a look at this fascinating creature:
Click for more images
A few amazing tidbits:
- It creates the longest anchor lines (the tough singular threads that hold the central orb to other objects like tree branches) known among arachnids: over 80 feet!1
- The webs it spins are made from a material that is considered to be the most durable biological material known. It’s nearly twice as resilient as any other known silk, over ten times stronger than Kevlar!2
- It creates the largest orbs (the central spiral portion) known among arachnids: up to seven feet across, nearly 30 square feet!3
- The impressive webs are all spun by the female members thanks to the extreme sexual dimorphism of the species. Males are up to five times smaller and spend most of their time in some rather devoted sexual rituals.
It’s only found in Madagascar, an island full of novel creatures found nowhere else. The special abilities of this spider allow it to dominate a niche that other spiders simply can’t encroach upon: the open airspace above rivers and ponds. The huge nets it spins above bodies of water allow it to capture 30 or more insects at once– quite an effective method! Its apparatus allows it to catch so much food that it sometimes wraps several insects in one cocoon, an unusual habit among arachnids. Despite the size of their creations, the creators are not very large: adult females are usually less than one inch long.
The Darwin’s bark spider was discovered by Matjaz Kuntner, Ingi Agnarsson and team of the Smithsonian National Museum of Natural History in the Andasibe-Mantadia National Park. More detailed information on observations and methods can be found in “Web gigantism in Darwin’s bark spider”, the description of the species by Kunter and Agnarsson in the Journal of Arachnology. They are currently researching how the Darwin’s bark can create such long anchor lines. For more images see the articles referenced below as well as this page.
While I was looking up information on the Darwin’s bark I came across more amazing spider discoveries from recent times. Cerbalus aravensis is the largest spider of its kind in the Middle East, but it wasn’t discovered until early in 2010. It’s therefore quite unfortunate that the small area that appears to encompass its range is now in danger. Within the long list of discoveries from the Greater Mekong region was the world’s largest spider, Heteropoda maxima. Also known as the Giant huntsman spider it was discovered in 2001 in Laos. This speedy cave predator has a legspan of 12 inches! I find it rather inspiring that such incredible creatures existed without being known to science for so long. The diversity of our natural world is simply astounding.
- Kuntner, Matjaz; Agnarsson, Ingi. “Web gigantism in Darwin’s bark spider, a new species from Madagascar (Araneidae: Caerostris)”. The Journal of Arachnology (American Arachnological Society) 38: 346–356. [↩]
- Lalueza-Fox, C.; Agnarsson, I.; Kuntner, M.; Blackledge, T. A. (2010). “Bioprospecting Finds the Toughest Biological Material: Extraordinary Silk from a Giant Riverine Orb Spider”. PLoS ONE 5: e11234. [↩]
- Kuntner, Matjaz; Agnarsson, Ingi. “Web gigantism in Darwin’s bark spider, a new species from Madagascar (Araneidae: Caerostris)”. The Journal of Arachnology (American Arachnological Society) 38: 346–356. [↩]
