Introduction to Insect & Spider Body Parts

Author: Nicole VanderSal

Overview: This lesson gives an introduction to the basic insect and spider body plans and then goes into more detail of specific insect mouthparts, wings, and leg types, different spiders and other common invertebrates. The students use a worksheet to guide them while they closely examine specimens. If no specimens are available, the lesson can be easily modified by having students draw their own insects using the different leg types and mouthparts and describing what habitat and food resources their insect uses.

Lesson Concepts:

  • All insects have inherited the same basic body plan: three body sections and six legs.
       — Insect mouthparts and legs have been modified to serve different functions.
       — By looking at the structure of these body parts, we can often figure out what habitat an insect lives in and what food it eats.

  • All spiders have the same basic body plan: two body sections and eight legs.
       — Different types of spiders make different webs and have different body shapes.

  • There are also many other invertebrates that are neither spiders nor insects.

Main Goals:The main goal of this activity is to show students what insects and spiders are (how to identify an insect and spider) and how they differ. These differences can indicate where the spider or insect lives or what it eats.

Grade Span: 6–8

Materials:

  • Specimens or pictures of different insects and spiders

  • Blank paper for each student

  • Insects, Spiders and Other Invertebrates handout (pdf) for each student [See a sample of the handout filled in (pdf)]

  • Hand lenses, magnifying glasses or dissecting microscopes for observing specimens

Time: 40 minutes

Grouping: Students should observe at least two specimens or pictures, but pairs of students can share supplies.

Teaching Tips:
Good insects to use for specimens or pictures include: grasshopper, fly, butterfly/moth, beetle, wasp/bee. Because it is difficult to distinguish between spiders without knowing what web they build, it is better to use pictures that include webs for this.

Procedure:

I. An Introduction to Insects

  1. On their blank sheet of paper, have student do a quick drawing of an insect. (3 minutes)

  2. Ask students to explain what their insect looks like. Introduce the word "Character(s)" at this point to describe the specific features (traits) that the insects have.

  3. As students describe their insects, list the characters on the board. Your list can be divided into two parts: What all insects have and What some insects have. The first list should include: body sections (three), number of legs (six), eyes (normally two but some insects have lost their eyes because they live in caves), antennae (two), mouthparts and legs. There are other characters that some insects have, so if students list these, write them on a list of what some insects have. These include the number of wings (zero, two, or four: wings are often used to identify the type of. Focus on the characters that all insects have in common, because these are the characters that we use to identify an insect from other invertebrates. (5 minutes)

  4. Pass out the Insects, Spiders and Other Invertebrates handout (pdf) to each student. Complete the drawing and fill in the blanks together as a class to ensure that all students have the same information. (5 minutes) Students may already know what the body parts of an insect are called, but if not make analogies to the head and the abdominal and thoracic cavities of humans (if you have talked about this before).

    1. The drawing: Talk about the functions of each section and have students draw the structures as you talk about them:

         — The head is where the eyes, mouth, and antennae are located, so the insect sees, smells, eats and tastes with the head ("ears" of insects are generally located on the thorax, abdomen or legs).
         — The thorax is where all of the muscles for moving the insect are located. The wings and legs all attach to this section.
         — The abdomen is where digestion and reproduction occur (i.e., the stinger of bees is actually the structure they use to lay eggs: it just happens to also work very well for defense also).

    2. The sentences: Fill in the blanks of the sentences to demonstrate the idea that the different body sections of an insect have different functions.

      Briefly mention that the bottom of the worksheet shows some of the different body parts that insects have. You can often tell insects apart by looking at these characteristics.

II. Identifying Insect Body Parts

Have students look at the specimens or pictures and try to figure out what legs, wings and mouthparts their insects have. If you have all students looking at the same specimens/pictures, you can go over each specimen/picture as a whole class. (10 minutes)

  • Grasshoppers have one pair of jumping legs, two pairs of thick wings (they are not hard, but also not clear, one pair covers the other pair), and chewing mouthparts

  • Flies have normal legs, one pair of clear wings, and poking (mosquitoes) or licking mouthparts (the spit up enzymes, break down food externally and then lick it back up)

  • Butterflies/moths have normal legs, scaly wings (the scales come off if you touch them), and sucking mouthparts (usually curled up tightly unless eating)

  • Beetles can have jumping, digging or swimming legs, one pair of hard wings and a pair of clear wings hidden underneath, and chewing mouthparts

  • Wasps/bees have normal legs, two pairs of clear wings, and chewing or sucking mouthparts

III. An Introduction to Spiders

Explain that the first section of a spider is just like the first two sections of an insect squished together. It is called the cephalothorax [where the eyes (most spiders have eight eyes), mouthparts (fangs), pedipalps (small legs by the mouth), and legs all attach]. The abdomen of the spider is similar to insects (digestion and reproduction) but they also produce silk here (comes out of spinnerets at the rear of the abdomen). (7 minutes)

If you have pictures of spiders or other invertebrates, you can have the students look at those now. Otherwise you can move on to the assessment option described below.

IV. Assessment: Drawing an Insect (10 minutes)

  1. Divide the class into pairs or groups of threes or fours and give each group a piece of paper with two descriptions of insects on them (see sample scenarios below). Have the students draw what they think the insects would look like.

  2. When the drawings are complete, have someone from each group draw one of their insects on the board and have the class guess what habitat it lives in and what it eats.

Note: If students are too shy to draw up on the board, the teacher can draw different insects on the board and have the class guess their lifestyle. However, this activity is designed in part to have the students become more comfortable drawing and talking in front of the class, so please emphasize that there are no right or wrong insects that they draw, and it is alright to be creative!

Sample scenarios:

  1. An insect that eats other insects that live on the top of flowers

  2. An insect that lives on lily pads and eats insects on top of and in the water

  3. An insect that sneaks up on frogs and eats the slime from the back of the frogs

  4. An insect that gets its food from flowers that are all very close together

  5. An insect that gets its food from flowers that are very far apart

  6. An insect that lives in streams and eats fish

  7. An insect that drinks the blood of sea otters

  8. An insect that lives in the tops of trees and catches insects that fly by

You can choose to have all of the groups draw the same two or three scenarios and see what different insects they come up with, or have them all do different ones and have the class guess what their scenario was.

You can also have students make up more options to draw and you have to guess the scenario if there is still more time.

Extensions: This lesson is the first in a series of lessons about collecting insects and spiders in the schoolyard, curating and identifying specimens.

 
Copyright