Spider Survey

Arachne was a girl who was the best weaver in all the Greek Isles. She could weave such beautiful things on her loom that she challenged the goddess Athena to a weaving contest. This made Athena angry! Athena unraveled all of Arachne’s work and changed her into a spider. Arachne and her descendants were doomed to weave all their lives.

Spiders are arachnids

Scientists place spiders in a group called Arachnids (class Arachnida), named after the legendary girl Arachne.

All spiders have eight legs, two body parts, simple eyes (most have eight eyes!), no wings, no antennae, and a body covered by an exoskeleton. (Insects [class Insecta] also have a body covered by an exoskeleton; however, they have six legs, three body parts, and antennae. Insects also may have wings and compound eyes.)

The two body parts of the spider are the cephalothorax and the abdomen. The cephalothorax is a combination head and thorax;
this is where the legs, eyes, and mouthparts are. Spinnerets are located on the underside of the abdomen. Spinnerets produce silk, which is a protein material called fibroin. The spider’s body also has sensory hairs that allow the spider to detect vibrations.

Nearly all spiders are venomous. Most spiders found in the United States cannot bite through human skin and would not cause damage if they did. In Australia there are several spider species that must NOT be handled. Be sure you know what types of spiders are found in your area before using this lesson in Australia. The venom is delivered through poison ducts that come from a gland at the base of the chelicerae on each side of the spider’s mouth. The pedipalps located on each side of the chelicerae may be used for feeling. They also may have tiny sharp teeth along the edge to help the spider grasp prey.

A spider typically begins life wrapped in a waterproof egg sac.
The sac may contain from 1 to 3,000 eggs. When spiderlings hatch, they may cling to the back of their mother for several days. Other spiders, like those described in the children’s book Charlotte’s Web, climb to a high spot, raise their abdomens, and squirt out a silk “balloon” that catches the wind and carries the spiderling to a new home.

Spider silk is the strongest natural fiber found. For its size, it is stronger than steel. It can stretch to five times its original length without breaking. There are at least seven different types of silk. No spider makes all seven kinds.

Orb weavers make five or six of the seven types of silk, more than any other spider. They make webs with a scribbly pattern in white in the center. The silk is a liquid as it leaves the spinnerets; it hardens as it is drawn out. One kind of silk goes into the framework of a web. A second type gets coated with stickum as it passes through the spinnerets. The third type of silk is for tying up prey. The fourth is used for making egg sacs. The fifth is strung out behind and tacked down as the spider walks, like a safety rope.

How spiders get food

Web-tending spiders build webs and wait for a meal to arrive. Because they are inactive, web-tending spiders can go for a month or more without food. Once something does hit the web, the spider must decide if it is food or something that will harm it. Because most web-building spiders have poor eyesight, they use the vibrations in the web to determine if the item in the web is food or an enemy. If it is food, the spider wraps it in silk. A pinch from the chelicerae immobilizes the prey and injects enzymes that begin to liquefy the prey’s internal structures. When the spider is ready to eat, it sucks out this predigested liquid.

More active hunters, such as the wolf spider, use more energy and require more food than web-dwelling spiders. Crab spiders hide in flower petals to capture bees. The fishing spider can walk on a thin film of water and carries a bubble of air underwater in its search for prey.

Leaders should review the following:

Leaders should make their own preliminary inventory of spider activity in the habitat area before taking learners there. Spiders, like their insect prey, are more active during warmer weather.

Fall and Spring are the best seasons for this lesson. If the lesson is offered in the Fall, learners could monitor spider activity over the school year to discover for themselves when spiders are most active.

Using the information in the "FYI” section, lead a discussion about spiders. Adapt the information to the age of the learners. Using pictures from illustrated children’s books, compare and contrast the body parts of spiders and insects. Ask older learners to draw pictures to show these differences.

Ask learners if they have seen spiders in the habitat area. Where have they seen them? What were the spiders doing?

With the whole group, create an observation sheet to record information about spider webs. Coach learners to write questions for the sheet that document information such as web size; types of plants or other objects webs attach to; location of spiders; presence and location of wrapped prey; location of the web in regard to sun, shade, or other factors important to spiders.

Make a photocopy of the group’s observation sheet for each learner. Take the learners to the pond to get a more focused idea of the spider activity at this time of year. Ask learners not to handle the spiders or disturb the webs. What questions do learners have about spiders? Have learners do some library research to learn more about spiders.

Older learners could use a compass and measuring tape to create a map of spider web locations in the habitat.

Before beginning this section of the lesson, decide how much time you will give learners to observe the habitat area spiders. Learners will get the most from this activity if they spend time observing a spider and its web before designing an investigation. They might do just one exercise, observe the webs each week for a month, or observe the webs over the whole school year. Be sure to explain these guidelines to learners before they begin their investigation design.

After learners have had time to observe the behavior of spiders in the pond habitat, group them in their teams and ask them to follow the steps outlined in the 4-H Science Inquiry Model to create an experiment design, including a materials list. Avoid experiments that could harm the spiders. Experiments could test food preferences, web location preferences, and spiders’ reactions to various stimuli; or monitor activity at different temperatures.

When all the teams have completed their experiment design, ask them to share them aloud with the group. Allow learners to ask the teams questions about their designs.

Pass out the materials requested by each team. Facilitate data collection in the habitat as needed over the predetermined time period.

At the end of the experiment period, ask the teams to analyze and interpret their observations and the data they collect from any experiments, and give a summary report to the group. Ask each team to explain how they could apply what they learned to spiders that do not live at the school. The next time they find a spider in their bedroom, how will they respond?