Camouflage Mirage

Target Audience: The grade level for this lesson is kindergarten through second grade (ages 5-7).

Estimated Time: This lesson’s time frame is approximately an hour for the activity and a half hour each day for the experiment. The experiment should be repeated once daily for five days.

Next Generation Science Standards: This lesson teaches to:

K-LS1-1 From Molecules to Organisms: Structures and Processes

2-LS4-1 Biological Evolution: Unity and Diversity

Overview: This lesson gives insight into the biological importance of camouflage using Ra­mu­lus ar­te­mis, the Vietnamese Stick Insect, as a model organism. Students will learn about the diversity of insects, camouflage as a survival mechanism, and how to perform scientific investigations through experimentation.

Learning Objectives:

Identify an insect and define what makes it unique, including what it may eat and the habitat where it may live.

Define camouflage and give examples of organisms that utilize camouflage as a survival mechanism.

Develop a hypothesis.

Carry out a scientific investigation including collecting data and replication of the experiment.

Draw conclusions based upon the data collected in the scientific investigation.

Background Information:

Insects are among the most diverse and unique animals present on earth. To be classified as an insect, an animal must possess an exoskeleton, three body segments (a head, thorax, and abdomen), six jointed legs that are symmetrically placed with three on each side of the body, and a pair of antennae. Insects will also feature either one or two pairs of wings, with some having no wings at all. There are over one million discovered species of insects that are present in every ecosystem and serve every role within that ecosystem (“About Insects,” n.d.). Many insects utilize “camouflage”, blending into the surrounding environment in order to hide. This is done to evade predation or to accomplish predation of another organism (Boudreau et al., 2011).

Stick insects are masters of camouflage. The Vietnamese Stick Insect, Ramulus artemis, is an insect of the order Phasmatodea that includes all walking sticks or stick insects. Its body is long and slender, typically green or brown, and can reach lengths of over 20 centimeters long if the front legs are in an extended position. Its behavior, as well as its appearance, contributes to its camouflage abilities. In the day-time hours, it stays very still and attaches to a similar looking substrate. It is a nocturnal creature and will most likely move to eat only at night. To blend into its environment, the Vietnamese Stick Insect will walk in a shaking, unsteady pattern in order to mimic a branch blowing in the wind (“Vietnamese Stick Insect,” n.d.).

The Vietnamese Stick Insect is a docile creature that is easy for children to handle. The insect should be allowed to walk onto the hand of the person handling it rather than directly picking it up. There are no hazards associated with the insect, making for a great pet. Please note before purchasing these insects for use in the classroom, a permit may be required from the USDA. This ensures that the organisms would not cause damage to the environment if it were to escape from the classroom (for more information on this permit, please see https://www.aphis.usda.gov/aphis/ourfocus/planthealth/import-information/permits/regulated-organism-and-soil-permits/insects-and-mites/ct_insects).

To keep this insect healthy in captivity, it requires an enclosure at least three times its body length. A glass enclosure such as a terrarium would be preferrable for students to able to make observations during the experiment. These insects eat the leaves of the following plants: blackberry, oak, raspberry, privet, rose, and hazel, as well as organic lettuce. Ensure that the food source has not been treated with any insecticides prior to feeding. The enclosure can be kept at room temperature and does not require any special lighting or certain humidity. A water dish is not needed; the enclosure can be sprayed lightly with water every other day (“Vietnamese Stick Insect,” n.d.).

Schedule:

Day 1: Complete Introductory Activity and Begin Experiment

Days 2-4: Repetition of Experiment and Data Collection

Day 5: Last Day of Experiment, Draw Conclusion, and Assessment of Concepts

Materials for the activity:

Stick Insect coloring page (credit: supercoloring.com)

Coloring utensils

Activity Instructions for Teacher:

Prior to students arriving to class, print out the appropriate amount of coloring pages so that each student has their own.

Pass out the coloring page to each student and instruct the students that they will be learning about insects today.

Ask students “Do you know what makes an insect an insect? When you look down at the ground and you see something moving, how do you figure out what it is?” Have students raise their hands and make guesses.

After students speculate and make guesses, explain that scientists have a way of figuring out what makes an insect an insect because all insects share unique features (exoskeleton, head, thorax, abdomen, antennae, and six legs). Using the coloring page, point out these features on the stick bug and count the legs. Ask students “Is this an insect?” and have them answer. Ask students to think of other insects they are already familiar with. If they say organisms that are not insects, point out the feature that excludes them from being an insect (i.e. a spider has eight legs, millipedes and centipedes have more than six).

Explain to student that the insect on their page is an insect called a walking stick or stick insect. Introduce the concept of camouflage by having the students first only color the insect. Ask students “Why is the stick insect shaped like that?” and have them answer. Explain that the insect is using camouflage in order to hide from other animals that would try to eat it. Explain that the insect can mimic the branches of a tree by appearing as the same shape and color. To test students understanding of this concept, ask students to camouflage the stick insect they already colored by coloring in the branches and the background. Ask students “What other animals can you think of that also use camouflage?”

Materials for the Experiment:

Clear enclosure, such as an aquarium, with lid that allows air flow (https://www.amazon.com/Aqueon-Aquarium-Fish-Tank-Size/dp/B01MRCNVSY/ref=sr_1_7?_encoding=UTF8&c=ts&dchild=1&keywords=Aquariums&qid=1605193158&s=pet-supplies&sr=1-7&ts_id=2975461011 and https://www.amazon.com/Exo-Terra-Screen-Cover-Gallon/dp/B00LH2HOZO/ref=pd_bxgy_img_2/134-1815261-3691807?_encoding=UTF8&pd_rd_i=B00LH2HOZO&pd_rd_r=8805b660-e6a9-4d6f-9ef1-7aa5eff788c1&pd_rd_w=TZIFK&pd_rd_wg=2fRHN&pf_rd_p=ce6c479b-ef53-49a6-845b-bbbf35c28dd3&pf_rd_r=8SAHE5TGAVTJZYAZ7TEH&psc=1&refRID=8SAHE5TGAVTJZYAZ7TEH for example)

An adult Vietnamese Stick Insect (can be purchased https://www.backwaterreptiles.com/feeders/stick-insects-for-sale.html)

Branches that can be collected from around the school yard, cut into two separate similar lengths and shapes

Non-toxic paint in a bright color (suggested pink, red or blue, but not green or brown)

Instructions for Experiment:

The day before the experiment, paint one of the branches with the non-toxic paint and allow to dry completely overnight so that all paint fumes evaporate. Print out the appropriate number of data sheets so that each student has their own.

Place the natural looking tree branch (the one that has not been painted) on one side of the enclosure and place the painted tree branch on the other far side of the enclosure so that the branches have space between them.

After the activity is finished, explain to students that they will now perform an experiment to test the Stick Insect’s camouflage ability. The experiment is being performed to give the Stick Insect a choice of branch, and test whether it picks the one into which it can best camouflage.

Explain what a hypothesis is and ask students whether they think the Stick Insect will prefer the natural branch or the painted branch and why. Have students circle their hypothesis on their data sheet.

Procedure for Days 1-4:

Have a student helper remove an adult Vietnamese Stick Insect by allowing it to walk onto their hand.

Place the insect in the middle of the enclosure in between the two choices of branches and return the lid.

Check back after 24 hours and observe which side of the enclosure the insect has chosen.

Record the data on the data sheet.

Repeat steps 1-4 for the next four days.

Procedure Day 5:

Make the final observation of what side of the enclosure (and what branch) the insect has chosen and record the data on the data sheet.

Review the data and draw a conclusion of whether the insect prefers the natural branches, or the painted branches based on how many times the Stick Insect was present on each branch or side of the enclosure. Record the conclusion on the data sheet.