By Megan Brophy '14, Ali Garwood '15, Sarah Fronseca '15, & Bryce Dahm '15
I submitted the essay on “Wolf Spider” from Intersections this fall as it caught my attention from its first edition. The group of writers surprised me with the humor as well as their determination for accurate information. We consulted Dr. Stephen Johnson for scientific literacy. The group then clarified and strengthened each revision of their paper. When the group presented to the seventh graders in Jackie Kilby’s science classroom, their work reached the seventh-grade audience. Moreover, their presentation to the middle school science students further strengthened the group paper as they selected details that might be memorable for a younger audience. One member of the Intersections group wrote in reflection that the seventh-graders were “intrigued (or grossed out) by the wolf spider. I enjoyed teaching them a little something about this creature and it was a fun group project to work on. I liked that we were able to choose what topic we did and how we wanted to present it…” The group also worked together to edit and polish.
A loud shriek echoed down the long, white hallway of the lower level of Graham and startled the handful of girls doing their laundry; I one of them. Curious as a Cheshire cat, I sauntered my way down the hall to discover the source of the sound deriving from the computer lab. I opened the door to find Sarah standing on the table in the corner with a horrified expression on her face and Meghan laughing manically at her overreaction to the problem: a brown spider, no larger than half an inch, scurrying across the floor toward the door. Sarah whipped out her cell phone and called Bryce, the manly environmentalist that he is, to come take care of the situation and allow Sarah to feel comfortable setting foot back onto the ground. Bryce burst in the doorway a few minutes later with a Tupperware container and, with care, scooped up the harmless little guy in one swift motion, carrying it outside and letting it go in the grass. After laughing about the fiasco, we were intrigued by this small creature and began to research into it. We found out that it was called a wolf spider, and this is the organism we decided to investigate for our research paper.
We began our researching process by first deciding a broad topic: local nature. From there, we determined a narrower topic to find more specific information – wolf spiders. Our main research question would be “what impacts do wolf spiders have on us as humans and on the global community?” This topic was narrow enough to allow us to focus on one subject in local nature and expand this idea over a large scale. It proved challenging enough because our presentation was aimed toward seventh graders, and to capture and hold their attention we had to be creative and focus on ideas that would be interesting to them. We did this by creating a colorful poster that contained various fascinating facts about the wolf spider and presenting a power point slide show with pictures and further details about the creature. We rewarded our audience by handing out spider-shaped cookies if they answered questions correctly after we had presented our information. Our topic was grounded enough because rather than revolving around moral issues, we focused on a more scientific subject. Some keywords used in our search for information included “wolf spider”, “Iowa”, “environmental impact”. “importance”, “arachnid”, and “mythology.” All of these keywords helped pinpoint information that was specific and related to our overall inquiry of the impact that wolf spiders have on their environment, as well as other species.
According to Iowa State University’s Department of Entomology, the wolf spider ranks as one of the most common spiders found in Iowa. These creatures range in size from half an inch to two inches, and are brown to gray in color with various lines and markings (Oklahoma State University). The wolf spider has eight legs; one pair of legs nearest the mouth and in front of the walking legs serves as sensory appendages that are also used for sperm storage in males (Gupta). One biologically necessary characteristic of wolf spiders is their eyesight: eight eyes are arranged in three rows with four small eyes comprising the first row, two large eyes in the second, and two medium-sized eyes making up the third row at the top of the head (Anders). Had the lights gone out in the computer lab of Graham as Bryce attempted to capture the wolf spider, we could have used the eye-shine of this little guy to our advantage; a reflective layer of cells in the back of each eye called the tapetum lucidum serves to increase the amount of light hitting the spider’s retina (Dbvoe, Small, and Zvargulis 26). By shining a flashlight at the wolf spider, we would have clearly seen the light reflected off its eyes, similar to a cat. Because wolf spiders are mainly nocturnal creatures, this characteristic is essential for survival – it enables them to utilize light and see better at night (Gupta). This unique trait led us to question what biological purpose lay behind such great eyesight of the wolf spider, and we discovered that the reason related to its eating habits.
In his book Deserts, environmentalist Michael Allaby explains that “wolf spiders chase their prey, using their speed and strength to catch and overcome their insect prey. Web-spinning spiders lie in wait for prey and do not need good eyesight, but wolf spiders see well . . . they are able to detect small movements and form sharp images” (146). We learned that the feeding behavior of different species is determined by a combination of evolutionary and environmental pressures. The wolf spider performs one
of the most sophisticated mechanisms for acquiring food – by hunting – which requires that the organism locates, pursues, and handles prey singly. Some wolf spiders attack prey from their burrow, while others actively leave on a hunting voyage (Bernhard 35). Their prey normally includes insects and other invertebrates such as crickets, ants, grasshoppers, small frogs, lizards, mice, or other spiders. It is not uncommon for wolf spiders to attack insects larger than themselves. Once it captures its prey, a wolf spider will oftentimes roll onto its back and wrap its legs around it to hold it in place before biting (University of Michigan). As expected in the circle of life, the wolf spider also has many predators. A few of these include owls, shrews, toads, birds, small reptiles, and various predatory insects, the most prominent a predatory wasp. When a wolf spider is caught by this wasp, it is stung into paralysis and eaten alive by the wasp’s larvae. A wolf spider might even sacrifice a leg to escape when being preyed upon, which compromises its ability to capture prey or avoid predators in the long-run (Sharp). One major predator of wolf spiders are humans. That spider found in Graham was probably more scared than Sarah! Wolf spiders do have venom, but they rarely bite unless they are handled and feel threatened. Even if one did bite a human, their venom is not potent enough to be fatal. This is not to say a wolf spider bite would not be painful, though! If a bite were to occur, the worse consequences would include inflammation, pain, redness and itchiness, and these symptoms could last up to ten days (University of Kentucky). Though not nearly as dangerous as a brown recluse or black widow, it was probably best that Bryce did not handle the spider with his bare hands – just in case!
The sexual behaviors of wolf spiders are quite interesting. Males perform a specific type of courtship to obtain a mate and must approach the female waving his front legs to identify himself and make known his intentions – otherwise he may end up being her prey! He begins the courtship with jumping and a papal drumming, which communicates his desires for the lady-in-waiting. If his rhythmic serenade is worthy of her commitment, he mounts her. “The female often continues to move around and catch prey with the male on her back. He does not seem to think that her casualness compromises the passion of their relationship” (Sharp). After mating, the female lays dozens of eggs at one time and uses her silk to wrap them up for protection. She then carries the sac on her abdomen until her babies are ready to hatch. Once they hatch, the spiderlings live on their mother’s back for a few weeks until they are mature enough to live independent lives (Newton). Many people are simultaneously intrigued and disgusted by the sight of a female wolf spider carrying many squirming spiderlings on her back – it certainly is a unique characteristic of the wolf spider life cycle!
Like all organisms, wolf spiders play an essential role in the ecological systems they live. In fact, they are “more important to humans in the balance of nature than most other groups of animals” (Hillyard 179). Their effects stretch from locally to globally, and this can be seen through a variety of instances where wolf spiders are abundant. There are approximately 2,300 known species of wolf spiders found around the world wherever there are enough insects to eat (University of Michigan). One example of an impact by the wolf spider is in the tropics; here, they eat a plethora of pests and are themselves a meal for birds and other predators. If this natural balance becomes distorted, then the insect pests multiply so quickly that they are capable of completely consuming a food crop. With spiders as the predators, a rate of ninety-nine percent mortality in insects is nothing unusual (Hillyard 179). Spiders are increasingly being seen as indicators of ecological health because they respond more rapidly to changes in their particular environment as they are mobile and generally do not live long. This is especially noted in forests, where the number of spiders decreases rapidly as levels of atmospheric sulfur dioxide increase (181). Unfortunately, researchers are finding that “because of pollution and habitat destruction, the number and diversity of spiders is under serious threat” (182). The natural balance between spiders and insects is disrupted even at a local level, linked to excessive use of chemical pesticides (180).
Spiders can be advantageous even at a local level! Humans can “conserve spiders as allies in the battle against destructive insect pests and tolerate occasional spiders in fruits and vegetables or risk chemical residues on their food” (180). In this manner, each individual wolf spider consumes about five to fifteen small insects per day and would be a great natural way of removing chemical pesticide use. An interesting fact about spiders is that “agriculturists are finding that spiders should be encouraged generally in crops, orchards, vineyards, plantations, and forests” (181). With Iowa as a state largely focused on crop production and ensuring that it is efficient and healthy, this method of using the natural cycle of life to destroy pests might prove more beneficial in the long-run. “Whenever humans use chemical agents to combat the “destructive” insects of field . . . they also unwittingly destroy part of the world of the ground. In so doing they interfere, not infrequently to their own disadvantage, with this delicately balanced system of natural interactions” (Grzimek 50). Research has shown that to mass-release spiders for this use on fields is not practical – rather those that are naturally available must be encouraged. “Wolf spiders are highly mobile and ready to colonize new fields. They prey on pest insects before the latter can increase to damaging levels” (Hillyard 180). The most prominent downfall to this process is that many consumers of produce are reluctant to purchase it due to the possibility of having a spider or two in their product. This leads to a controversial topic relating to spiders – arachnophobia.
Arachnophobia – as demonstrated by Sarah’s response to seeing the little creature scurrying about on the floor – is prominent in many cultures around the world. This fear of spiders can be correlated with biophilia – a term coined by Harvard professor and Pulitzer Prize-winning author Edward O. Wilson. This is the idea that humans have an “innate tendency to focus upon life . . . and affiliate with them emotionally” (Bekoff 121). This theory incorporates the idea that humans have evolved to respond much more strongly with natural stimulus – such as animals – over artificial ones. The responses may be that we find pleasure in animals or respond negatively to them. One example of this is that “humans have a proclivity to fear snakes but not frayed electrical wires” (122). This type of behavior is thought to result from inborn tendencies – products of our evolution in relationship with nature. Snakes and spiders are largely feared and this is perhaps because “ancient people who were naturally more wary of these two animals must have fared better . . . than people who were not”. This contrasts the fact that humans are not yet prepared by evolution to learn as quickly about artificial objects like wall outlets and guns (121). Thus, the expression of fear and avoidance by Sarah at discovering the wolf spider most likely resulted from years of evolution where one’s survival once depended on it. While some protostome species instill a sense of fear for many people, spiders and other creatures have represented fortune for some cultures – some even provide food or medical treatments. Others are widely recognized and respected for their functional and beneficial influences on ecosystems (Grzimek 41).
This respect or fear is found in myths and literature throughout the course of history. Arachnid – the classification of spiders – is a term derived from Greek mythology in which the mother of all spiders was originally a woman named Arachne (Grzimek 35). Highly skilled in weaving and spinning wool, she boasted of her talent. Arachne claimed that the jealous goddess Athena could not do any better than her and this upset Athena in the worst way. Challenged to a weaving contest by Athena, Arachne obliged and promised to “suffer whatever punishment the goddess deemed necessary”. Arachne’s work was so exquisite and flawless that Athena became outraged and tore the tapestry to pieces. Because Arachne was ashamed and felt guilty for her actions, she surprised Athena by hanging herself. Athena took pity on her and decided to bring her back to life in the form of a spider (Lee). “Arachne lived out the remainder of her life spinning thread from her belly and using it to weave a web – behaviors that would be carried on by all descending spiders” (Grzimek 35). This story demonstrates how spiders have played major roles as benevolent and feared figures in various cultural myths and beliefs.
From a simple encounter with a wolf spider in the basement of a dorm building, we acquired much knowledge about these creatures. From mythological stories to mating habits to their physical characteristics, these arachnids certainly have much more going on than most humans are aware of. Overwhelmed with fear, Sarah – and plenty of others who are petrified by spiders – usually do not think about the environmental impacts of such small organisms. Globally and locally, wolf spiders prove to play essential roles in the ecosystems they thrive in. Wolf spiders can be beneficial when used as a natural pest control for agriculture, and they prove to keep insect populations under control. We are thankful that we were able to gather all of this information about the wolf spider and present it to middle school students as a way to demonstrate that not all spiders are harmful and are even important for the health of our planet! Next time we are startled by a spider, hopefully we think twice before stomping on it and instead handle it much like Bryce did as he took it back out to the natural world – with care and respect.
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