OBJECTIVES:

• Classifying arthropods and other little garden critters over time
• How do the arthropod and other little critter populations change through time?
• Observing and classifying different types of arthropods over time
• Learn about how seasonal changes affect arthropod populations
• Learn to use a graph to show collected data with multiple variables

VOCABULARY:

• arthropod
• insect
• head, thorax, abdomen, antenna, compound eye, wings
• molt

MATERIALS:

• Insect anatomy pdf worksheet  (optional)
• Insect book pdf       
• Insect data book at home
• Insect data booklet
• Scissors
• Glue
• Index cards
• Creepy crawly line graph and example

BACKGROUND:

In this long-term project, students collect data related to arthropods. A scientist that studies arthropods and other creepy crawlies is called an entomologist They learn the characteristics of arthropods and various subtypes. Students work as teams at different plant stations. They shake vegetation to collect arthropods and other little critters on a white cloth or sheet. They then classify them, using their identification cards, count them, make observations, and record and ultimately graph their results. Over time, they should see arthropod habitat preferences and variations in arthropod populations due to seasonal change.

Arthropods are bilaterally symmetrical and have jointed body segments with a pair of appendages attached to each body segment. The body is covered with a cuticle (thickened substance) which comes off ("molts") as the arthropod grows. There is no internal skeleton. The circulatory system of arthropods is very simple, and they reproduce by laying eggs. Many insects go through metamorphosis during their life cycle. So, a butterfly is the adult insect, but the caterpillar is the same insect in one of its early stages and looks more like a "worm" than an insect. Many arthropods, like mosquitoes, spend most of their life in an aquatic form before they metamorphose into flying insects.

Identification of arthropod types is not easy, because there are so many "creepy crawlies" out there. Arthropods are divided into two major groupings. One group (called chelicerates) includes spiders, scorpions, ticks and horseshoe crabs. They have no antennae and the first pair of appendages are pincher-like. The second major grouping of arthropods (called mandibulates) include most of the common arthropods, such as bees, flies, butterflies, ants and beetles. We will be concentrating on the more common arthropods, which are characterized by a three-part body – head (a), thorax (b) and abdomen (c). Wing covers or elytra (d), wings (e) and antennae (f) are usually present.

PROCEDURE:

1. INTRODUCTORY LESSON – Review key points from the Introductory video/PowerPoint lesson: What are arthropods? What are their key characteristics?
2. ARTHROPOD ID CARDS – Students cut out the cards and assemble. They punch a hole on the side of each card and tie cards together with yarn to make a flip chart. Students will use these identification cards to help them identify arthropod species.
3. Students are grouped into 2 or 3-person teams and each team receives the Observation Booklet they will use during the year.
4. Class goes over experiment methodology, and each team fills in the Problems, Hypothesis, Materials and Procedures sections of their booklets.
5. Each team is given a specific location outside and team members describe the area and types of plants in it (if known) in their Observation Booklet.
6. Each team goes to their designated area of plants and puts a tray covered with cloth or white paper under the plants. One team member shakes the plant 10 times carefully, but firmly. Teams categorize the insects that have fallen onto the tray using their arthropod ID cards and put counts in their booklet in the "Try 1" column.
7. The other two team members take turns shaking the plant 10 times each in the same area and put counts into their booklets under the “Try 2” and “Try 3” columns.
8. Add up the totals of each type per day and enter in “Total” column.
9. Fill in observations and in the booklet draw one of the arthropods.
10. OBSERVATIONS OVER TIME – Teams should visit their stations and collect data at least twice monthly in October and November, once a month in December and January and twice a month in February and March. Note: Students may find few insects in the winter months and rainy periods.
11. RESULTS AND GRAPH – Students should graph their results at the end of March and discuss what arthropod types were the most common, what seasonal patterns they see overall and what patterns they see between plant stations. For example, at what time of the year did they find the most and least arthropods? Do certain arthropods prefer certain types of plants over others? How does the information students learned about arthropods fit with what they learned in 1st grade (light changes over the seasons) and 2nd grade (plant growth rate changes with the seasons)?