Nature Notes: Eight-Legged Wonders
Spiders are one of those species that tend to get a bad reputation, being the subject of many myths and folklore throughout history. Being depicted as a sign of death, destruction, and bad luck, people sometimes think spiders have it out for them. Today, many do not think twice before squishing them with a shoe or sucking them up into their vacuum. The reality is that the majority of spiders in the Midwest are harmless, with only a few species capable of causing us harm by biting.
Spiders fall into the class of Arachnids, having 8 legs, 2 body parts, and lacking antennae/wings. The head and thorax are fused forming the cephalothorax which is connected to the abdomen. The legs connect to the cephalothorax, however, spiders have another pair of appendages called pedipalps, located near the head. Spiders also possess fangs which help with injecting venom. With over 50,000 identified species residing on all continents except Antarctica, spiders are a very diverse species. Scientists are sure there are hundreds of undiscovered species of spiders still out there, living deep in the rainforests.
Spiders are an incredible species that have some mind-blowing adaptations while serving as an important part of the ecosystem. We tend to fear what we do not know, learning more about spiders is the first step to understanding and accepting them as your eight-legged neighbor!
Silk is created from the spiders’ spinnerets, a specialized organ, which they will use in a multitude of ways. Spider silk is incredibly strong and has a stronger tensile strength than steel! As well as being incredibly elastic, it is important that silk be very strong. The most well-known function of silk is to create a web that insects will get trapped in, making an easy meal for the spider. Not all webs will look the same. Some webs may look picturesque like they were carefully made with love, while some other webs may look as if the spider forgot how to make a web and just completely panicked. Nonetheless, there are four basic types of webs, cobwebs, sheet webs, funnel webs, and orb webs.
Cobwebs are the web we tend to see indoors the most, in the corners of a room or along window sills. Spiders that make cobwebs include, cellar spiders, common house spiders, and even black
widows! These irregular webs look
messy and jumbled, but this serves a purpose. The chaotic mess of a web will slow down insects walking through, giving the spider plenty of time to snag itself a meal. These webs will also protect the spiders while they sit in the center waiting for their next meal.
Sheet webs are shaped like a bowl, with a flat section underneath, like a cup and saucer. These webs are commonly found in shrubs and bushes or on the ground. Spiders that spin sheet webs include hammock spiders and dwarf sheet spiders. Hammock spiders will frequently hide in a curled-up leaf that is a part of the sheet web. Whereas dwarf sheet spiders prefer to create their webs on the ground in slight depressions. These webs will capture prey as they fall into the bowl, getting caught in the sticky silk.
Funnel webs resemble a sheet web, but have a hole that funnels downwards. This funnel is where the spider will sit waiting for prey, it can also back further into the opening to hide from any threats. Grass spiders will create their funnel web on the ground, pouncing on insects that walk across the web. Barn funnel weavers can be found outdoors, but are most commonly seen indoors in the corner of garages and basements.
Grass spider funnel web covered in dew. 📷 Nora W.
Orb webs are usually the webs we picture when we think of a spider web. With their spiral appearance and circular shape orb webs are stunning. Oftentimes the spider will be in the middle of the web but have an area nearby that they can hide in when not at the web. Many orb-weavers will remake their webs daily since they get damaged easily from wind, rain, and morning dew. Spiders that will spin orb webs include giant lichen orb-weavers, marbled orb-weavers, and garden spiders.
L: Orb web covered in dew. 📷 Nora W. Center: Banded garden spider. 📷 Delaney D. R: Marbled orb-weaver. 📷 Nora W.
On the Hunt
Not every species of spider will create webs to trap their prey, several species will actually ambush their dinner instead. These predatory spiders will create a small silk structure for them to rest in. Spiders such as wolf spiders and jumping spiders will go out in search of a meal, and pounce on the unsuspecting insect. These spiders often have great camouflage capabilities, which help fool the unsuspecting insect. Webless spiders will often lay eggs in sacs that are guarded by the female, or even carry the egg sacs on their back.
L: Female fishing spider protecting nursery web. R: Recently hatched spiderlings. 📷 Delaney D.
Bug Smoothies Anyone?
Web building spiders will immobilize their prey by wrapping it up in silk before enjoying a meal. Whereas spiders that ambush their prey will use their pedipalps to hold the prey while biting it. The bite that is delivered to insects injects venom, paralyzing the victim and causing chemical reactions to take place. The chemical reaction taking place inside the insect's body is causing it to break down into a soup-like consistency. Spiders will then use their straw-like mouths to suck up the liquid inside.
In a true feat of nature, a spider may take flight in an act called ballooning! To do so they will aim their abdomen into the air, and shoot out a string of silk. Wind will catch the silk making the spider airborne. Some may travel hundreds of miles, even ballooning over large bodies of water. Not all spiders will travel as far, some only taking flight in a desperate act to get away from a predator. See this phenomenon in action with this National Geographic video!
Spiders are a natural pest control – feeding on hundreds of insects that would otherwise be bothersome to us. Not only do they keep the buzzing mosquitoes away from you, but they also help keep pests from damaging crops, saving farmers money! Besides serving as an essential predator of insects, spiders are also a great source of food for other animals. Spiders are prey for birds, reptiles, and even other spiders!
The greatest threat to spiders is the loss of habitat, especially in rainforests and caves. When out in nature, keep an eye out for spider webs, and try to avoid breaking them. Another major threat is the lack of public support and awareness of spiders, due to fear. So what can we do about this? Spreading the word and education on spiders can help overcome those biases and fears. Highlighting all the benefits of spiders and the beauty of spiders can help bring us closer to understanding our eight-legged friends. Next time you come across a spider in your household, think twice about squishing them, and instead gently relocate them outdoors.
L: Yellow garden spider with a grasshopper. 📷Delaney D. Center: Giant lichen orb-weaver eating a dragonfly. R: Fishing spider with caterpillar. 📷 Nora W.