We love spiders at the Tacoma Nature Center, and once you know more about them, we think that you will love them, too.
We talk about “spiders” as if they are one thing, but spiders are not all alike. Some are big, some are small, some spin webs to catch prey, some don’t. Some are adapted to live outdoors, others are adapted to live in buildings, caves or other protected areas. In their more than 300 million years on Earth, spiders have adapted to all kinds of habitats and conditions and thrive on every continent but Antarctica.
Let’s start with the first thing most of us think of when we think of spiders — webs. Spiders are predators, meaning they eat other animals. A typical spider in this area can eat an estimated 2,000 insects a year. Spider webs are how some species of spiders catch their food.
Webs are made of spider silks, substances that have never been re-created by science. There are seven kinds of silk that spiders can make, depending on their species and gender. Spider silk is a protein that is at least as strong as steel, so spider webs can withstand wind, rain and being hit by spider prey. Each strand of the spider web is typically made of several strands of silk layered together for strength.
To capture insects, the web needs to be more than strong — it needs to be sticky so the prey can’t get away. We’ve all seen a fly or other insect wrapped up by a spider in the middle of a web. Insects and other prey fly or fall into the middle of a sticky web that holds them until the spider can reach them, immobilize them and wrap them up. The spider doesn’t stick to the web because it knows where the sticky threads are.
2,000 The estimated number of insects a typical spider in the South Sound can eat in a year.
The downside of having a sticky web exposed to dust, wind and other elements is that it gets ruined in a hurry, so sticky strands of spider webs typically last only one day. Spiders have to do continual repair to their webs. Some spiders have to make a brand new web each day They will eat their web so they don’t waste that protein, rest up a little and then get started on the day’s new web. Spiders were very early adaptors of the concept of recycling materials.
As much as we humans think of spiders as having webs, not all spider species spin webs to catch prey. Some species are passive hunters, building silk-lined funnels and waiting for prey to wander in. Others are active predators that hunt their prey just like a lion. There are also ambush hunters that take cover and pounce on prey that comes close. There is truly a spider for every niche.
There are around 3,000 species of spiders in North America. We don’t have that many locally, but we do have a wide variety of spiders here — indoors and outdoors. Did you know the spiders you see outside are usually totally different species than the spiders you find indoors and under buildings. The spiders that associate with buildings are generally not adapted to be outside. They live their entire lives indoors, largely unseen by humans.
Spiders are especially obvious to humans this time of year. That is not because there are suddenly more of them. This is the mating season for most species — they need to mate and lay eggs before the winter comes. Many spiders we see in the fall are males on the move looking for females. Males have to wander in search of more secretive and sedentary females to mate with in lots of spider species.
Fun with spiders
There are lots of ways for your family to explore different worlds of spiders as you make your way through your day.
Get down on the ground and follow a jumping spider for awhile, watch how it moves and how far it jumps. Or sit quietly and observe as a garden spider constructs a web. You will notice a pattern as these engineers weave their silk strands back and forth, layering them for strength. Think about how fast the webs come together. And remember this — nobody taught this spider how to build that web. They are born knowing how to build a web.
Pay attention to how many different kinds of spiders you see in a day. When you look closely, you will start to notice that the spiders you pass by every day are very different from each other. Look closely at a spider web, then see if you can draw it. What do you notice about the size, shape and pattern of the webs that different species of spiders create? Here is an online guide to help you identify spiders: spiders.us/species/filter/washington.
Here is a craft project where kids can to construct a spider web using a cardboard box, some yarn and their imagination: tinyurl.com/zvlgtx8.