External Insect Morphology

Question 1

What are characteristics of arthropods? (8)

Answer 1

Segmented bodies

Paired appendages

Segmented appendages

Bilateral symmetry

Exoskeleton

Dorsal heart

Open circulatory system

Ventral nerve cord

Question 2

What is metamerism?

Answer 2

a state of division of insect body into primary body segments

Question 3

What is a metamere?

Answer 3

A primary body segments

Question 4

How many metameres does the head have?

Answer 4

1-5

Question 5

How many metameres does the thorax have?

Answer 5

6-8 metameres

Question 6

How many metameres does the abdomen have?

Answer 6

9-20

Question 7

What is tagmosis?

Answer 7

an evolutionary phenomenon of grouping body segments into functional units

Question 8

What is a tagma?

Answer 8

a grouped segment of a functional unit

Question 9

What are four advantages of the exoskeleton?

Answer 9

Acts as protective armor

Protects from invasion by pathogens and harmful agents

Impermeable to water

Acts as a base for muscle attachment

Question 10

What is a disadvantage of the exoskeleton, and what must be done to overcome it?

Answer 10

Does not expand

Must be shed in order to grow- molting

Question 11

What are the layers of the exoskeleton cuticle? (4)

Answer 11

Epicuticle
Exocuticle
Endocuticle
Epidermis

Question 12

What is the epicuticle?

Answer 12

Non-living outermost layer

Question 13

What makes up the layers of the epicuticle? (4)

Answer 13

Cement- outermost layer

Wax- layer under the cement

Outer epicuticle

Inner epicuticle

Question 14

What is the exocuticle?

Answer 14

non-living layer under the epicuticle

Question 15

What is the endocuticle?

Answer 15

non-living layer under to exocuticle, above the epidermis

Question 16

What features are found in both the exocuticle and endocuticle? (3)

Answer 16

non-cellular

made of chitin to provide strength and rigidity

made of resilin to provide flexibility

Question 17

What is the epidermis layer, and what its function?

Answer 17

innermost, living layer

secretes substances involved in molting

Question 18

What are sclerites?

Answer 18

plate of the body wall surrounded by sutures or membrane

Question 19

What are sutures?

Answer 19

the line of fusion of two plates

Question 20

What is the membrane in the exoskeleton?

Answer 20

a thin and pliable cuticle

Question 21

What are setae?

Answer 21

hair-like projections of the cuticle that arise from a trichogen cell

Question 22

What are scales, and an example?

Answer 22

flattened setae that serve a “covering” purpose

Ex- wings of butterflies and moths, or bodies of silverfish and beetles

Question 23

What are spines, and their three functions?

Answer 23

Outgrowths of the cuticle, not produced by the cells

helps in grasping, clinging, and protection

Question 24

What makes up the sensory segments of the head? (3)

Answer 24

Eyes

ocelli

antennae

Question 25

What makes up the feeding segment of the head?

Answer 25

paired mouthparts

Question 26

What 5 different types of mouthparts are there, and an example?

Answer 26

chewing- grasshopper piercing and sucking- mosquito sponging- housefly siphoning- moth and butterfly chewing and lapping- honey bee

Question 27

What 3 segments make up the thorax?

Answer 27

Prothorax (closest to the head) Mesothorax Metathorax (closest to the abdomen)

Question 28

What kind of modification lets an insect run?

Answer 28

Cursorial leg modification

Question 29

What kind of modification lets an insect swim?

Answer 29

Natatorial leg modification

Question 30

What kind of modification lets an insect jump?

Answer 30

Saltatorial leg modification

Question 31

What kind of modification lets an insect grasp?

Answer 31

Raptorial leg modification

Question 32

What are three facts about insect wings?

Answer 32

An important development Wings are outgrowths of the cuticle Type and size vary, depending on need

Question 33

What are the layers of the wings?

Answer 33

Veins surrounded by a cuticle

Question 34

What two veins are found in the wings?

Answer 34

Longitudinal vein and cross-vein

Question 35

What five types of wings exist?

Answer 35

membranous wings (flies with haltere) tegmina (leather-like forewings- cockroach) hemelytron (half-wing; forewing for true bugs) Elytron (hardened front wing) Scaled covered wings

Question 36

What 3 things are found in the abdomen, and what is not found?

Answer 36

Has no walking appendages Possesses the ovipositor- egg-laying device Possesses the stinger- a modified form of the ovipositor Cerci- sensory structures

Question 37

What does the glandular setae do?

Answer 37

produces secretions involved in protection or communication

Question 38

What does the ocelli do?

Answer 38

light detection

Question 39

What is the ommatidium?

Answer 39

single eyes that form the ommatidia (compound eye)

Question 40

What does the ommatidium do?

Answer 40

Detects a color

Question 41

What kind of vision do insects have?

Answer 41

Developed to be sensitive to changing patterns and movement, not for highly detailed views

Question 42

How do insects perceive color? (3)

Answer 42

Insects can see higher wavelengths than humans Humans can see lower wavelengths than insects Most cannot see red

Question 43

What does the mesothorax hold?

Answer 43

Forewings

Question 44

What does the metathorax hold?

Answer 44

hindwings

Question 45

What are the parts of an insect's leg?

Answer 45

Coxa > trochanter > femur > tibia > tarsus > pretarsus

Question 46

What are halteres? (2)

Answer 46

balancing organs to help the insect fly Hindwings are modified into halteres