ã The Norwood Science Center 2005
Norwood Science Center
Animals
Grade 2
Background Information:
Crickets are insects that are frequently found in fields and meadows. Like all other insects, they have a segmented body, six legs, and an exoskeleton (bony or hard covering produced from the outer layer of skin). Their antennae are often longer than their body. Their wings lie flat over each other on top of the cricket's back. Crickets breathe through tiny openings on the sides of their body called spiracles. You can tell a male cricket from a female cricket by comparing the back ends of their bodies. A female cricket has a long tube projecting from the back. The tube, called an ovipositor, is used to lay eggs in the ground. The male cricket has no such tube.
There are several different kinds of crickets in the United States, but you'll most often find the common black field cricket, Gryllus assimilis. Field crickets live under rocks, boards, decaying logs, in the grass, or almost anywhere on the ground.
Crickets do not show the great physical change from stage to stage that other insects, such as butterflies, do. Cricket eggs are deposited in the soil sometime in the Fall and remain there throughout the Winter. With the arrival of warmer weather in the Spring, the eggs hatch into small crickets called nymphs. The nymphs look much like the adult crickets. The young nymphs feed and grow. When they become too big for their exoskeleton, the skin splits and a new larger exoskeleton forms and hardens. This is called molting. Nymphs can molt 5-13 times before they become adults. This process takes 5-8 months. Since crickets skip the pupal stage of development, they are said to go through incomplete metamorphosis.
Only a male cricket chirps. The chirp is produced when one wing is dawn across the other. The hard, rough surface on the underside of the wing is pulled across a hardened vein on the upper front of the other wing. The wing vibrates and makes the sound. Some crickets chirp right wing over left wing and others chirp left wing over right. The cricket's song is not just for your enjoyment. One kind of chirp is used to attract females. Another chirp is used as a warning to other males. Crickets are highly prized for their songs in China and Japan. The cricket is kept in a small bamboo cage so it can be fed and its song heard.
TITLE: CRICKETS
PURPOSE: Observe and study crickets
MATERIALS: (per pair of students)
Crickets (2)
Hands lens (2)
Petri dish, with cover
Prism viewer
Incomplete Metamorphosis Worksheet (2)
Scissors (2)
Petri dish cover
Glue stick
PROCEDURE:
Part 1: Observing the Cricket
01. Ask the following questions:
· What type of animal is a cricket? (an insect)
· What are some characteristics of a cricket? [three pairs of legs, antenna (maybe), three body parts (head, thorax, abdomen), compound eyes, and an exoskeleton (bones on the outside of its body)]
02. Distribute the hand lenses and a Petri dish containing a pair of crickets. Students should distinguish between each cricket by either giving each a number or name. Instruct them to write these differentiations in their notebooks.
03. Instruct students to carefully observe the cricket with the hand lens and identify as many of the following body parts as they can:
compound eyes / head
thorax (chest) / abdomen (belly)
04. Ask the students:
· Any other special body parts?
· Based on your observations, is the cricket an insect?
· What other animal does a cricket look like?
· Where is the cricket's mouth? How can you tell?
· Where are a cricket's eyes?
· Where are the cricket's antennae?
· What is their function of the antennae?
· Are your crickets male or female? How can you tell? (Point out that female crickets have a long, needlelike part extending from their abdomen called the ovipositor that deposits eggs.)
06. Ask the students, How do you think that crickets breath? (Point out that crickets breathe through small holes in the side of their abdomen called spiracles.) Have students try to observe the spiracles.
07. Explain to students that insects have compounds eyes that are actually hundreds and hundreds of lenses.
08. Distribute a prism viewer to each student. By looking through the prism, students can experience how the insect views the world through their compound eyes.
Part 2: Incomplete Metamorphosis
09. Distribute one Incomplete Metamorphosis Worksheet, Petri dish cover, glue stick, and pair of scissors to each student.
10. Taking turns, each member of the team should trace the circular shape of the Petri dish cover in the center of a page in their notebook.
11. Instruct students to cut out the four sections of the worksheet (the three stages of incomplete metamorphosis and the title section) and place them at the top of their desk.
12. Using the numbers on the classroom clock as reference, have students find the location of “three o’clock” on their traced circle. Students should glue the “egg” diagram at that location.
13. Have students locate “six o’clock” on their traced circle and glue the “nymph” diagram at that location.
14. Students should glue the “adult” diagram at the “nine o’clock” location on their circle.
15. By gluing the “title” section above the circle, the students have completed a visual representation of incomplete metamorphosis.
CONCLUSION:
01. After the students have observed the crickets, ask:
· How are crickets like plants? (Both are living organisms).
· How are crickets different from plants? (Crickets can move.)
· Since crickets do not make their own food, they cannot be called producers. What would you call them? (consumers.)
02. Guide students in the drawing of an insect in their notebook.
SOURCE:
01. Life Activities and Explorations. Houghton Mifflin Company, Boston, 1975.
02. Pets in a Jar. Viking Press, NY, 1975.
03. Food Chains and Webs. A Delta Science Module, Nashua, NH, 1989.
Crickets Gr. 2 07 Page 1 of 5