Wonders of Orb-Weavers
Published 9-7-2018
Recently a new visitor appeared in a corner of our backyard deck. She was resting on a beautiful silken web. It was a barn spider. I made a mental note to instruct my young grandchildren on the wonderful diversity of spiders on our next visit with them. Perhaps we will need to convert them from arachnophobes to arachnophiles. Knowledge borne of patient instruction will be our educational goal. This easily spotted specimen was dark brown with a large, round abdomen about 3/4” long.
What are spiders? They belong to a biological class of joint-legged arthropods, the most plentiful phylum in the animal kingdom by far. Arthropods include spiders and insects but spiders are distinct from the far more numerous insects. Spiders possess eight legs instead of six, only two body sections rather than insects’ three and they do not possess antennae or wings. They are carnivorous. There are over 45,000 spider species on the planet while there are well over one million different insect species. Of the 45,000 existing spider species there are 2800 orb-weaving spider species—180 of them in North America. Orb-weaving spiders make wheel or circular shaped webs. They are the third most plentiful family of spiders in existence. One of the most well known capabilities of spiders, orb-weavers in particular, consists of their web-spinning designed to ensnare their life-sustaining meals.
Few people have failed to read or encounter the plot of E. B. White’s Charlotte’s Web, a 1952 top children’s fantasy classic about Charlotte, the barn spider, who helped save Wilbur the runt piglet from slaughter by weaving messages of support for preserving Wilbur’s life on her web. Woven into the plot of the story is the fragility of life, including the frequent mention of flies which are naturally caught in Charlotte’s web. Charlotte eventually dies, but not before her genetic line continues in the birth of new spiderlings. There are many more positive life lessons woven through the classic’s story plot.
The web of orb weavers is a startling marvel of strength. Hundreds of feet of organic proteinaceous silk is produced by the spider and distributed through the animal’s spinnerets—silk spinning organs. The material from which spider webs are made is a marvel of function designed by the Creator of all Things. The diameter of spider webs is 1/10 of human hair, but ten times stronger than steel pound for pound. It is flow tolerant—stiff, then stretchy, then stiff again.
Construction of the orb-weavers’ web is an engineering feat practically unmatched in the animal world. She begins by floating a web line into the wind with the goal of attaching the end to a location some distance away. The spider attaches another single web to the original line to form a “Y.” Other spokes are constructed from the center point. Hundreds of concentric strands are then built on these spokes toward the middle. They are precisely spaced and meticulously attached as the spider extends the silken web from his spinnerets and attaches the sticky strands one spoke at a time in a deliberate act of precision engineering. Details of the intricate process are documented in many easily accessed YouTube videos—a wonderful resource for both young people and adults fascinated by the instinctive, mostly unlearned behavior of animals in the natural world.
Our spider is ready to capture her next meal. While she needs no help from humans in her predatory exploits, children and adults have been known to fling captured flies into the webs to observe the exhilarating result. Orb-weavers have poor eyesight but rely on vibrations from insects entrapped in the sticky web. Spiders have tiny brains only as large as a poppy seed. It is not really a brain typical of mammals but rather a tiny mass of “nerve tissue.” Somewhat complex architectural decision making is possible along with ability to sense the location of trapped flies trembling with desire to escape.
What neurological wonders result in such fascinating, deliberate behavior? Bioscientists are unable to propose a reductionist explanation. How is this behavioral pattern “encoded by neural networks?” Neuroethologists are “scientists who study the evolutionary and comparative approach to the study of animal behavior and its underlying mechanistic control by the nervous system.” The foregoing definition uses evolutionary as an adjective which hopefully explains the astonishing behavioral characteristics and ability of one of the most remarkable animals on Planet Earth. Other science writers offer us no additional help, offering description as a weak substitute for true explanation. Orb-weavers appear to possess a consciousness which cannot be explained except by the Creator of life itself.
Wikipedia introduced their lengthy article on “Animal Consciousness” with this statement: “In 2012 a prominent group of neuroscientists signed the “Cambridge Declaration on Consciousness,” which “unequivocally” asserted that “humans are not unique in possessing the neurological substrates that generate consciousness. Non-human animals, including all animals and birds, and many other creatures, also possess these neural substrates.” (emphasis mine)
The term consciousness generates a lively interest from behavioral scientists to theologians and many experts in between. We have submitted several posts on consciousness in humans and animals in the past. Our current post travels somewhat farther into discussion of a lower form of consciousness, this time in insects. Consciousness in humans, of course, is far more highly developed in terms of sentience and executive control. Consciousness in lower creatures, however, is also a bestowment of the Creator of All Things. Here is a link to our past post “Consciousness in Animals”—living things lower than man:
https://jasscience.blogspot.com/2017/02/consciousness-in-animals.html
https://jasscience.blogspot.com/2018/09/wonders-of-orb-weavers.html
