Zoology - TERRESTRIAL MANDIBULATES

Phylum Arthropoda

THINGS YOU NEED TO KNOW FROM THIS CHAPTER…

1. General characteristics of uniramians…
1. Where do you find most uniramians?
2. How many pair of antennae do they have?
3. How do they carry out respiration?
4. What are some examples of myriapods?
5. What are the tagmata of insects?
2. Class Diplopoda – what are they?
1. How many somites?

i. How many pairs of appendages per somite do they have?

2. What do they eat?
3. How do they defend themselves?
2. Class Chilopoda – what are they?
1. How many somites do they have?

i. How many pairs of appendages per somite do they have?

2. Where do you find the poison claws?
3. How do they see?
4. Where do you find them?
5. What do they do for a living?
6. Are they dangerous?
3. Class Insecta
1. Why are they, perhaps, the most important arthropod group?
2. Where are the appendages attached?

i. How many pairs of legs?

ii. How many pairs of wings?

3. Why have insects been such a successful group of animals? (Hint: You should be able to think of several reasons)
4. What type of eyes do they have?
5. What are their mouthparts called?
6. What are the segments of the thorax called?

i. What attaches to each segment?

1. Why can insects walk on ceilings?

ii. Where are the wings attached?

1. What do the wings consist of?

7. How many segments does the abdomen have?
8. Digestive system

i. What does the foregut consist of?

ii. What happens in the crop?

iii. What happens in the gizzard?

iv. What happens in the ceca?

v. What happens in the hindgut?

vi. What do most insects feed on?

1. What does phytophagus mean?

2. What does saprophagous mean?

3. What does hyperparasitism mean?

4. What does parasitoid mean?

9. How do insects carry out respiration?

i. Does their blood carry oxygen?

10. Sensory perception of insects?

i. What are sensilla? What do they detect?

ii. How do they hear?

iii. How do most insects see?

11. Reproduction

i. How do females attract males?

ii. How do males impregnate females?

iii. How many times in a lifetime does a female mate?

iv. Do they ever show parental care?

1. What does parental care do for survival of young?

12. What is metamorphosis?

i. What are the stages between molts called?

ii. What is unique about the last molt?

iii. What is the most common type of metamorphosis?

1. What are the stages of this lifecycle called?

iv. What type of metamorphosis is seen in grasshoppers?

1. What are the stages of this lifecycle called?

2. What are some other insects that do this?

v. What are the only insects that show direct development?

13. What is diapause?
14. How do insects defend themselves?
15. What are pheromones?
16. What is bioluminescence?
17. What is the social behavior seen in honey bees?
18. What is the social behavior seen in termites?
19. What is the social behavior seen in ants?
20. How do insects benefit humans? (Hint: You should be able to think of several examples.)
21. How do insects harm humans? (Hint: You should be able to think of several examples.)
22. What are some of the problems in insect control by humans?

I. Diversity and Characteristics

A. Uniramians are primarily _____________________ with a few found in

freshwater habitats.

1. Uniramia only have _________ pair of antennae and

appendages are always uniramous.

2. Uniramians use _____________________ to distribute

respiratory gases, similar to annelids.

B. The _____________________ include the centipedes, millipedes,

pauropods and symphylans.

C. The insects have reduced their body tagmata to head, thorax and

abdomen.

1. Abdominal appendages are greatly reduced or absent.

II. Class Diplopoda

A. Characteristics

1. Millipedes have _____________________ of legs per somite,

probably from fusion of two segments.

2. Their cylindrical bodies have from _____________________

somites.

3. The head has two clusters of simple eyes and a pair each of

antennae, mandibles and maxillae.

4. Each abdominal somite has two pairs of spiracles opening into

air chambers and tracheal air tubes.

B. Natural History

1. Millipedes are less active than centipedes; they walk with a

graceful rather than wriggling motion.

2. Most eat decayed plants but a few eat living plant tissue.

3. Most are slow moving and roll into a coil for defense.

4. Some secrete toxic or repellant fluids from special ___________

_____________________ on the side of the body.

III. Class Chilopoda – the centipedes

A. Characteristics

1. Centipedes are terrestrial and have flattened bodies with up to

_______________ somites.

2. Each somite, except the one behind the head and the last two,

bears __________________ of jointed legs.

3. Appendages of the first body segment form ________________

__________________.

4. The head has one pair of antennae, a pair of mandibles and one

or two pairs of maxillae.

5. Eyes on either side of the head consist of groups of

_________________.

B. Natural History

1. Centipedes are found under logs, bark and stones.

2. They are ___________________________, eating earthworms,

cockroaches and other insects.

3. The house centipede has 15 pairs of long legs and is common in

bathrooms and damp cellars.

4. Most are harmless to humans but a few large, tropical

centipedes are dangerous.

IV. Class Insecta

A. Diversity

1. Insecta are the most diverse and abundant of all arthropods.

2. The number of known species is estimated at

_____________________.

3. Insects play major medical and economic roles with humans,

and are critical to animal ecology.

B. Characteristics

1. Insects have _____________________of legs and often

_____________________of wings on the

_____________________ region of the body.

C. Distribution

1. Insects are found in nearly all habitats except the sea.

2. Adaptive Traits

a. Flight and small size makes insects widely distributed.

b. Their well-protected eggs withstand rigorous conditions

and are readily dispersed.

D. Adaptability

1. Most structural modifications are in wings, legs, antennae,

mouthparts and alimentary canal.

2. Specialization for eating only one part of a host plant allows

many insect species to coexist on a plant.

3. The hard and protective exoskeleton is well-adapted to life in

desert regions.

4. The exoskeleton is made of complex plates, or sclerites,

connected by hinge joints.

a. Muscles attaching sclerites allow precise movement.

b. The rigidity is due to scleroproteins and not mineral

matter; this lightness allows flight.

E. External Form and Function

1. The cuticle of a somite is composed of a dorsal notum, a ventral

sternum and a pair of lateral pleura.

2. Head

a. Usually there is a pair of large _____________________

eyes.

b. One pair of antennae vary greatly in form; they can feel,

taste and hear.

c. Mouthparts consist of a _____________________, a pair

of _____________________ and _____________________,

a _____________________ and a ____________________.

3. Thorax

a. The thorax consists of the _____________________,

_____________________ and _____________________;

each has a pair of legs.

b. Wings

1) If two pairs of wings are present, they are on the

___________________ and ___________________.

2) Wings consist of a double membrane.

3) Veins serve to strengthen the wing; the vein pattern

is used to identify insect taxa.

c. Legs

1) Walking legs end in terminal pads and claws.

4. Abdomen

a. The insect abdomen has from _____________________

segments; the last is reduced to a pair of cerci.

b. Larval and nymphal forms may have abdominal

appendages lacking in adults.

c. The external genitalia are usually at the end of the

abdomen.

5. Walking

a. Insects walk using the first and last leg on one side and

the middle leg on the opposite side in alteration with the

reverse; this provides stability.

F. Internal Form and Function

1. Nutrition

a. Digestive System

1) The foregut consists of the mouth with

_____________________,

_____________________, _____________________

and _____________________.

2) Some digestion, but no absorption, occurs in the

_____________________ as salivary enzymes mix

with food.

3) The _____________________ grinds food before it

enters the midgut, the main site of digestion and

absorption.

4) The _____________________ may increase the

digestive and absorptive area.

5) The _____________________ is primarily a site

for water absorption.

b. Most insects feed on plant tissues or juices and are

_____________________ or _____________________.

c. Many caterpillars are specialized to eat only certain

species of plants.

d. Certain ants and termites cultivate fungus gardens for

food.

e. Many beetles and other insect larvae eat dead animals

and are _____________________.

f. Some insects are predaceous on other insects or other

animals.

g. Many species are parasitic as adults and/or larvae.

h. Many parasitic insects, in turn, have parasites, which is a

condition called _____________________.

i. _____________________ live inside a host until they

eventually kill the host; they are important in pest control.

j. Mouthparts

1) Sucking mouthparts form a tube to piece tissues of

animals or plants.

2) Houseflies and blowflies have sponging

mouthparts; the soft lobes at the tip absorb food.

3) Biting mouthparts can seize and crush food.

2. Circulation

a. A tubular heart in the pericardial cavity moves hemolymph

forward through the dorsal aorta.

b. Hemolymph has plasma and amebocytes but does not

function with oxygen transport.

3. Gas Exchange

a. Terrestrial animals are faced with the dilemma of

exchanging gases but preventing _____________________

loss.

b. The _____________________ system is a network of

thin-walled tubes that branch throughout the insect body.

c. _____________________ open to the tracheal trunks;

there are two on the thorax and 7-8 on the abdomen.

d. A valve on the spiracle often cuts down on water loss; the

spiracle may also serve as a dust filter.

e. The tracheae branch out into fluid-filled tubules called

tracheoles that reach individual body cells.

f. This system provides gas transport without use of oxygen-

carrying pigments.

g. Very small insects transport all gases by simple diffusion.

h. Aquatic insect nymphs may use tracheal gills or rectal

gills.

4. Nervous System

a. Insect nervous systems resemble that of larger

crustaceans, with fusion of ganglia.

5. Sense Organs

a. Many insects have keen sensory perception.

b. Most sense organs are microscopic and located in the

body wall.

c. Different organs respond to mechanical, auditory,

chemical, visual and other stimuli.

d. Mechanoreception

1) Touch, pressure, vibration, etc. are picked up by

sensilla.

2) A _____________________ may be a single hair-

like seta or a complex organ.

3) They are distributed widely over the antennae, legs

and body.

e. Auditory Reception

1) Sensitive setae (_____________________) or

__________________________ may detect airborne

sounds.

2) Organs in the legs can detect vibrations of the

substrate.

f. Chemoreception

1) These usually are bundles of sensory cell

processes located in sensory pits.

2) They may occur on mouthparts, antennae and

legs.

3) Some insects can detect odors for several

kilometers.

4) Feeding, mating, habitat selection and host-

parasite relationships are mediated through chemical

senses.

g. Visual Reception

1) Insects have two types of eyes: simple and

compound.

2) Honeybee studies indicate that the ocelli monitor

light intensity but do not form images.

3) Insects can see simultaneously in almost all

directions; the image is myopic and fuzzy.

4) A bee can distinguish ultraviolet light we cannot

see, but cannot detect shades of red.

h. Other Senses

1) Insects are very sensitive to temperature,

especially by cells in antennae and legs.

2) Insects also detect humidity, proprioception, gravity

and other physical properties.

6. Reproduction

a. Sexes are separate in insects and fertilization is usually

internal.

b. Sexual Attraction

1) Female moths secrete a powerful

_____________________ to attract males from a

great distance.

2) Fireflies use flashes of light to detect mates.

3) Some insects use sounds, color signals and other

courtship behaviors.

c. Many insects deposit sperm in the vagina during

_____________________.

d. In some orders, _____________________ are transferred

or deposited on substrate.

e. The female may only mate once and store the sperm to

fertilize eggs throughout her life.

f. Females may lay a few eggs and provide care of young, or

lay huge numbers.

g. Butterflies and moths must lay eggs on the host plant if

the caterpillars are to survive.

h. Wasps may have to locate a specific species that is the

only host to their young.

Watch this video of wasps that turn lady bugs into zombie protectors!

G. Metamorphosis and Growth

1. Various forms of metamorphosis produce degrees of change

among different insect groups.

a. Most insects change form after hatching from an egg.

b. Each stage between molts is called an

_____________________.

c. Insects develop wings during the last stage where they

are useful in reproduction.

2. _____________________ Metamorphosis

a. About 88% of insects undergo this complete

metamorphosis.

b. This separates the physiology of larval growth, pupal

differentiation and adult reproduction.

c. Larvae and adults often live in completely different

environments and therefore do not compete.

d. After several larval instars, a larval moth or butterfly

becomes a pupa inside a cocoon or chrysalis.

e. Pupae often pass the winter in this stage; the final molt

occurs and the adult emerges in spring.

f. Stages are _____________________________________

________________________________________________.

3. _____________________ Metamorphosis

a. Some insects undergo a gradual metamorphosis.

b. Grasshoppers, cicadas, mantids, true bugs, mayflies and

dragonflies exhibit this metamorphosis.

c. Young are called nymphs.

d. Stages are ____________________________________

_______________________________________________.

4. Direct Development

a. Silverfish and springtails have young similar to adults

except in size and sexual maturation.

b. Stages are egg-juveniles-adult.

c. These are primitively wingless insects.

H. Diapause

1. _____________________ is a period of dormancy in the annual

life cycle that is independent of conditions.

2. Winter dormancy is called hibernation; summer dormancy is

called estivation.

3. Any stage (eggs, larvae, pupae or adults) may remain dormant to

survive adverse conditions.

4. This allows them to synchronize with the environment.

5. Diapause is genetically determined but it may be triggered by

environmental cues such as day length.

6. Diapause always occurs at the end of an active growth stage; the

insect is then ready for another molt.

I. Defense

1. Protective coloration, warning coloration and mimicry are

protective adaptations.

2. Stink bugs and others have repulsive odors and tastes.

3. Some insects are aggressive (e.g. bees and ants).

4. The monarch caterpillar incorporates a poisonous substance

from its food plant, milkweed.

5. The bombardier beetle can spray an attacking enemy with

irritating chemicals.

J. Behavior and Communication

1. Many insect behaviors are complex sequences of responses.

2. Most insect behavior is _____________________ but some

involve simple learning.

3. _____________________

a. These chemicals are secreted by one individual to affect

the behavior of another individual.

b. Pheromones attract the opposite sex, trigger aggregation,

fend off aggression and mark trails.

c. Bees, wasps and ants can recognize nestmates and

signal an alarm if strangers enter the nest.

6. Sound Production and Reception

a. Sounds are used as warning devices, advertisement of

territory, and courtship songs.

7. Communication

a. Tactile communication involves tapping, stroking, grasping

and antennae touching.

b. Some beetles, flies and springtails use bioluminescence.

c. Some female fireflies mimic another species’ flash pattern

and attract males and then eat them.

8. Social Behavior

a. Some social communities are temporary and

uncoordinated.

b. Other social groups are highly organized and depend on

chemical and tactile communication.

c. Caste differentiation is common in the most organized

social groups.

d. Honeybees

1) Honeybees have a few male drones, a fertile

female queen and many sterile female workers.

2) Males come from unfertilized eggs; fertilized eggs

produce females in this haplodiploid system.

3) The development of a fertile queen occurs because

she alone is fed royal jelly.

4) A queen secretes “queen substance” to prevent

workers from maturing or feeding larvae any royal

jelly.

5) A honeybee hive of 60,000-70,000 individuals

continues indefinitely.

6) Honeybees have a communication system; scouts

can inform workers on the location of food.

e. Termites

1) A fertile king and queen fly away to start a new

colony; they mate and lose their wings.

2) Sterile members are wingless and become workers

and soldiers.

3) Soldiers have large heads and defend the colony.

4) Reproductive individuals secrete inhibiting

pheromones that produce sterile workers.

f. Ants

1) Ants differ from termites; ants are darker, hard-

bodied and have a thread-like waist.

2) In ant colonies, the male ant dies after mating.

3) Ants have wingless soldiers and workers, and often

have variations of these castes.

4) Ants have also evolved slavery, fungus farming,

sewing nests together, tool use, and herding.

V. Insects and Human Welfare

A. Beneficial Insects

1. Insects produce honey, beeswax, silk and shellac.

2. Of more economic importance, bees pollinate $10 billion worth of

food crops in the U.S. annually.

3. Predaceous and parasitoid insects are vital in controlling many

pest insect populations.

4. Dead animals are rapidly consumed by fly maggots.

5. Insects are critical components of most food chains and a central

food for many fish and birds.

B. Harmful Insects

1. Harmful insects eat and destroy our plants and fruits.

2. Nearly every cultivated crop has several insect pests; this

requires substantial money for insect control.

3. Insects also destroy food, clothing and property.

4. Medically important insects include vectors for disease agents.

a. Warble and bot flies attack humans and domestic

livestock.

b. Malaria is carried by Anopheles mosquitos and is the most

common major world disease.

c. Yellow fever and lymphatic filariasis are also mosquito-

borne.

d. Fleas carry plague, a disease that changed human history

in the Middle Ages.

e. Lice carry typhus fever.

f. The tsetse fly carries African sleeping sickness.

C. Control of Insects

1. Broad-spectrum insecticides damage beneficial insect

populations along with the targeted pest.

2. Some chemical pesticides persist in the environment and

accumulate as the move up the food chain.

3. Some strains of insects have evolved a resistance to common

insecticides.

4. Biological control is the use of natural agents, including diseases,

to suppress an insect population.

5. Some natural predators or parasites of insect pests can be

raised and released to control the pest.

7. Release of sterile males can eradicate the few insect species

that only mate once.