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18.3: Arthropods and Insects

Difficulty Level: At Grade Created by: CK-12

Lesson 18.3: True or False

Name___________________ Class______________ Date________

Write true if the statement is true or false if the statement is false.

_____ 1. Some estimate that 80% of all species living on earth today are arthropods.

_____ 2. The body segments of an arthropod are the antipode, midpode, and postpode.

_____ 3. Coxal glands get rid of wastes.

_____ 4. Trilobites were terrestrial arthropods.

_____ 5. Arthropods were the first terrestrial animals.

_____ 6. Centipedes and millipedes are characterized by their poison claws.

_____ 7. When crustaceans grow, they shed their exoskeleton by molting and grow a new one.

_____ 8. Hexapoda refers to the six legs of insects.

_____ 9. All insects have only two body regions: thorax and abdomen.

_____ 10. Wings are part of the endoskeleton of an insect.

_____ 11. Some insects use their wings to make sound.

_____ 12. Many insects have a larval stage.

_____ 13. All insects in a colony have the same job.

_____ 14. Termites are solitary insects.

_____ 15. Some crops depend on insects to pollinate them.

Lesson 18.3: Critical Reading

Name___________________ Class______________ Date________

Read these passages from the text and answer the questions that follow.

Structure and Function of Arthropods

Arthropods range in length from about 1 millimeter to 4 meters (about 13 feet). They have a segmented body with a hard exoskeleton. They also have jointed appendages. The body segments are the head, thorax, and abdomen. In some arthropods, the head and thorax are joined together as a cephalothorax.

The arthropod exoskeleton consists of several layers of cuticle. The exoskeleton prevents water loss and gives support and protection. It also acts as a counterforce for the contraction of muscles. The exoskeleton doesn’t grow as the animal grows. Therefore, it must be shed and replaced with a new one periodically throughout life. This is called molting. The jointed appendages of arthropods may be used as legs for walking. Being jointed makes them more flexible. Try walking or climbing stairs without bending your knees, and you’ll see why joints are helpful. In most arthropods, the appendages on the head have been modified for other functions. The figure below shows some of head appendages found in arthropods. Sensory organs such as eyes are also found on the head.

Arthropod Head. Arthropods have evolved a variety of specialized appendages and other structures on their head. (Image courtesy of CK-12 Foundation and under the Creative Commons license CC-BY-NC-SA 3.0.)


1. Do arthropods vary in size? If so, by how much?

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2. How do arthropods keep from drying out?

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3. What do arthropods use for movement?

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4. What are the main body segments of arthropods?

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5. How do arthropods sense their environment?

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Lesson 18.3: Multiple Choice

Name___________________ Class______________ Date________

Circle the letter of the correct choice.

  1. A protective, waterproofing structure consisting of several cuticle layers is the __________.
    1. endoskeleton
    2. exoskeleton
    3. labium
    4. ocelli
  2. Shedding of the exoskeleton is called
    1. molting.
    2. bolting.
    3. incision.
    4. extrasensation.
  3. Structures that collect liquid wastes from the blood of some arthropods and concentrate it are the
    1. Macrolipid tubules.
    2. Malphigian tubules.
    3. coxal glands.
    4. toxal glands.
  4. The caterpillar is the __________ stage of a butterfly
    1. larval
    2. pupal
    3. gamete
    4. adult
  5. There are fossil records of the earliest arthropods to evolve, the __________.
    1. millipedes
    2. ticks
    3. mites
    4. trilobites
  6. Arthropods that are mainly aquatic, scavengers or predators, and have two pairs of antennae and claws are in the subphylum
    1. Myriapoda.
    2. Chelicerata.
    3. Crustacea.
    4. Hexapoda.
  7. Arthropods that mainly terrestrial, can be predators or parasites, and have eight walking legs and two body segments are in the subphylum
    1. Myriapoda.
    2. Chelicerata.
    3. Crustacea.
    4. Hexapoda.
  8. Ants communicate with chemicals called
    1. silica.
    2. metronomes.
    3. biomes.
    4. pheromones.

Lesson 18.3: Vocabulary I

Name___________________ Class______________ Date________

Match the vocabulary word with the proper definition.


_____ 1. process in which a larva undergoes a major transformation to change into the adult form, which occurs in amphibians, arthropods, and other invertebrates

_____ 2. excretory structures that collect waste from the blood and concentrate it

_____ 3. a tube-like structure for gas exchange

_____ 4. sensory structure in invertebrates such as arthropods that detects chemicals and other stimuli

_____ 5. oldest known arthropod, which is now extinct and known only from numerous fossils

_____ 6. jaw-like head appendage in arthropods for holding and swallowing food; or the upper jaw of a mammal or other vertebrate

_____ 7. jaw-like head appendage in arthropods for grasping, biting, and chewing food; or the lower jaw of a mammal or other vertebrate

_____ 8. process in which an animal sheds and replaces the outer covering of the body, such as the exoskeleton in arthropods

_____ 9. excretory structure that transports waste from the digestive tract to the anus

_____ 10. life cycle stage of many insects that occurs between the larval and adult stages and during which the insect is immobile, may be encased within a cocoon, and changes into the adult form

_____ 11. a fused head and thorax

_____ 12. phylum containing insects, spiders, and lobsters


a. antenna

b. Arthropoda

c. cephalothorax

d. coxal glands

e. Malphigian tubules

f. mandible

g. maxilla

h. metamorphosis

i. molting

j. pupa

k. trachea

l. trilobite

Lesson 18.3: Vocabulary II

Name___________________ Class______________ Date________

Fill in the blank with the appropriate term.

1. A sensory organ on the head of some arthropods that detects chemicals is a(n) __________.

2. Enclosed in a cocoon is the __________.

3. __________ are excretory structures that transfer waste from the digestive tract to the anus.

4. The __________ is the lower jaw.

5. The __________ is the upper jaw.

6. __________ is the shedding of the exoskeleton.

7. __________ are excretory structures that collect waste from the blood and concentrate it.

8. The first arthropods, which are now extinct, are the __________.

9. A fused head and thorax segment is a __________.

10. The __________ is a tube-like structure through whic gases travel.

11. __________ describes the transformation of a larval to adult form.

12. Honeybees communicate to other honeybees about the location of a food source with the __________.

Lesson 18.3: Critical Writing

Name___________________ Class______________ Date________

Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.

What advantages do flying insects have over arthropods that cannot fly?

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