1. List and briefly describe the characteristics
shared by the Phylum Annelida and the Phylum Arthropoda and which seem to
relate the two phyla.
2. Describe the general anatomy, functioning
and value of the unique appendages of arthropods.
3. List and briefly describe the usefulness
and disadvantages of the chitin exoskeleton of arthropods including its contribution
to muscle efficiency.
4. Give the name of the type of segmentation
in arthropods and explain how this is an advantage over the situation displayed
in the annelids.
5. State the function of gills, book lungs,
trachaea and malphighian tubules and relate each of these to the general
habitat of the arthropods which possess these organs.
6. Describe the advances over previous phyla
of the arthropod nervous system including the nature of and value of instincts.
7. List the groups of animals in the four subphyla
of the Phylum Arthropoda.
8. State the embryologic origin, location and
function of chelicerae, pedipalps, mandibles and antennae and relate each
of these organs to the kind of arthropods which have them.
9. Discuss several beneficial as well as harmful
aspects of members of the Phylum Arthropoda.
10. Discuss metamerism and define tagmata.
11. List and discuss several reasons contributing
to arthropod success.
12. Identify members of the arthropod classes
by highlighting the number of legs and antennae each posses.
13. Discuss the SubPhylum Chelicerata, specifically
the Class Arachnida. Highlight chelicerae, pedipalps, book lungs, and spiracles.
14. Identify several types of webs used by
spiders.
15. State three other groups of organisms besides
the arachnids that belong to the class Arachnida.
16. Justify the claim that the Decapod class
of the Subphylum Crustacea have the greatest direct impact on people.
17. State two ways in which crustaceans differ
from other arthropods.
18. Discuss the endrocine system of the crustaceans.
19. Detail and discuss the unique features
of the crustacean digestive and respiratory systems.
20. Discuss the arthropod nervous system in
general and detail the advancements in the development of the eye.
21. List three classes of the subphylum Uniramia
and give examples of each.
22. List several features of the class Insecta
that differentiate it from other members of the arthropod phylum.
23. Discuss the direct and indirect (synchronous
and asynchronous) mechanisms of flight in the insects.
24. Discuss the origins of flight in the insects
and also discuss what this has allowed insects to do.
25. Discuss three types of metamorphosis displayed
by insects.
26. Describe the selective advantage of complete
metamorphosis.
27. Describe the structure and function of
malphighian tubules and tell why this type of excretory organ aids in adaptation
to dry-land habitats.
28. List the main kinds of stimuli to which
insects respond instinctively and the sense organs used to receive these
stimuli; give specific illustrations of instincts triggered by these stimuli.
29. Distinguish between hormones and pheromones,
and give specific illustrations of the function of each.
30. Analyze the ways in which different insect
species can affect crop production.
31. Outline the life cycle and reproductive
pattern of a colony of honeybees and describe the ways in which the body and
instincts of honeybees are modified to suit their ecological niche.
Resources: Text: Animal Diversity, Chapter
12
Internet Resources:
http://www.ucmp.berkeley.edu/arthropoda/arthropoda.html
http://www.perspective.com/nature/animalia/arthropoda.html
http://www.uio.no/~mostarke/forens_ent/forensic_entomology.html
http://www.public.iastate.edu/~entomology/ReesourceList.html
http://www.ent.iastate.edu/Misc/InsectsAs Food.html
http://www.mhhe.com/hickmanad4e
Phylum Arthropoda
-nearly 1 million species recorded (3X more
than all other species combined),
# of species staggering!
-Estimates: 200 million insects for every
living individual if all died they could
cover the entire surface of the earth one
inch thick
*Extremely successful group
Effects on Humanity: Quite possible that
if the arthropods were gone,
we would be as well
BENEFITS: -link in food chain
-pollination, most seed
plants would not exist, ~65% insect pol.
-human food, specifically
crustaceans, several million pounds annually
from Gulf of Mexico
alone (primarily shrimp)
-silk
-spider silk can be
stronger than steel of the same gauge.
-insectivorous arthropods
help control insect pests Ex. lady bugs
-soil dwelling arthropods
scavengers and decomposers
-Esthetic and psychological
Butterflies- art,
literature
Scarab Beetle- sacred
in anchient Egypt
HARM: *Ticks, mites, mosquitoes,
fleas, lice; look upon people, their pets and
livestock as just another
meal (parasitic larva can also be involved)
-painful bites of stings
in self-defense, more people die of bee and
scorpion stings than
by snakebite (or shark attacks!)
*Black Widow- neurotoxin,
attacks CNS
*Brown Recluse- hemolytic,
produces death of tissues and skin
surrounding bite
*vectors of disease:
Tick- Lyme disease, Rocky Mt. Spotted fever;
Mosquito- malaria, yellow
fever, viral encephalitis, filarial worms
(tsetse flies --->
trypanosoma; rat fleas ---> bubonic plague)
-destroy wooden structures;
termites, boring crustaceans
*crops and ornamental plants
destroyed
-stored grains
ANIMALS TO BE COVERED:
PHYLUM ARTHROPODA
SubPhylum Chelicerata
Class Arachnida- scorpions,
ticks, spiders, harvestmen
SubPhylum Crustacea- crabs, lobster,
shrimp, barnacles, crayfish
SubPhylum Uniramia
Class Diplopoda- millipedes
Class Chilopoda- centipedes
**Class Insecta
ARTHROPOD GENERAL CHARACTERISTICS:
1. Bilateral symmetry, metamerism
tagmata- fused segments (Ex.
Head and Thorax in crayfish --->cephalothorax)
Head, Thorax, Abdomen (heteronomous
)
**2. Jointed appendages
3. Exoskeleton (chitin); Molting (Ecdysis)
4. Complex muscular system
Striated ---> movement
Smooth ---> visceral organs
*Both attach to exoskeleton
5. Complete digestive system, specialized
mouth parts
6. Open circulatory system w/ contractile
heart, hemoglobin/hemocyanin
7. Respiration varied; body surface,
gills, trachae, booklung (Arachnids)
8. Excretion: similar to annelid system
Green Glands (antennal) in
crayfish
Malphigian tubules (insects
and arachnids)
9. Nervous system: similar to annelid w/ some advanced sensory
10. Usually dioecious, usually internal
fertilization
Oviparous- devel of eggs
outside female
Ovoviviparous- eggs devel inside
female w/o additional nourish.
*Metamorphosis- change in
form during development
Parthenogenesis- development
w/o fertilization
REASONS FOR SUCCESS:
1. Adaptations/advances allow them to inhabit
any environment, perform any function
ecologically.
2. Exoskeleton- cuticle secreted
by epidermis, protective, mouth parts (mandible),
sensory organs (setae), wings; chitin
-growth does not include cuticle, therefore, Molting (Ecdysis)
3. ***Jointed Appendages
-locomotion/food handling- allows
movement away from adverse conditions, allows
greater chance of survival,
adaptation
4. Air directly to cells and tissues (tracheae), maintenance of high metabolism.
5. Highly developed sensory organs
-compound eyes, receptors for smell,
touch, "hearing"
-receptors allow them to be "in
touch" with surroundings
6. Reduced competition through Metamorphosis
; adult eats differently than juvenile,
less intraspecies competition
7. Complex behavior patterns
-Instinctual (innate)- major
agent in determining behavior
Ex. migration, avoidance of light,
etc.
-learned behavior- social behavior (bees/ants)
-not capable of Insight Learning
(when faced with new problems, cannot reorganize
memories to construct new response)
8. Flight- wings from cuticle, expose insects
to whole new arena
Phylum Arthropoda
SubPhylum Chelicerata- six pairs
of appendages
-1st pair Chelicerae, most
anterior (pinchers, "jaws", fangs)
Bite and poison prey (no mandible,
no chewing, obtain food by sucking)
-2nd pair- Pedipalps (=palps)
slightly behind chelicerae, resemble legs. Males use
enlarged end of pedipalp as
copulatory organ
-3rd- 6th pair- Walking legs
Class Arachnida: spiders,
scorpions, ticks, mites, harvestmen
Segmentation (tagmata): cephalothorax,
abdomen
-Spiders; no external segmentation,
ceph joined to abdo by pedicel (waist)
-Predaceous- fangs on chelicerae conduct poison; digestive fluids injected into prey
RESPIRATION- Book Lung unique to spiders
(air pockets extending into blood filled
chamber, air enters through lung slits
Trachea- air tubes take air directly to tissues, air enters through spiracles
EXCRETION- Malphigian tubules
-solutes and waste products diffuse
into tubules that drain fluid "urine" into intestine
**very similar to nephridia
-rectal glands reabsorb some solutes and recycle, conserve fluids
SENSORY- eight simple eyes w/lens and retina, detects motion, a few can form images
Sensory Setae- sense air currents,
changing tensions, vibrations allows spider to
judge size or messages being relayed
Webs- spinnerets w/ microscopic
tubes run to silk glands. Protein secretions harden
upon exposure to air. Webs for
trapping, sperm and egg sacs, bridge lines, nursery
Orb web- typical round
web
Sheet web- flat mats found on ground
Funnel web- acts as nest,
"funnels" prey; common in tall grasses in this area
(also in yards, gardens, porches,
etc.)
Triangle web- between twigs
Tangle web- untidy web, usually found on ceilings,"cob webs"
REPRODUCTION
-male spins web, deposits sperm, then picks
it up and stores in pedipalp
-pedipalp inserted into female genital opening
and into seminal receptical
-usually a courtship ritual, tapping on
webs
-female lays eggs in silk cocoon
-young molt several times to adult **no
metamorphosis
Scorpions- very short cephalothorax
2 abdominal segments
-post abdominal stinging apparatus
(neurotoxin)
-few lethal, however, a number of
those are located in Arizona and New Mexico
Harvestmen- daddy long legs
-no pedicel (waist)
-abdomen shows external segmentation
-can do without one or more legs
-scavengers
Ticks and Mites- ectoparasites
-cephalothorax and abdomen fused
-attachment to vert. or invert., suck
blood until distended then drop off to digest
-disease vector
Mites- scab mite- sheep, loss of
wool
Sarcoptes- mange in dogs
chiggers
Subphylum Crustacea (shelled)
- crayfish, lobster, shrimp, crab
*includes mostly aquatic (and mostly marine),
one order terrestrial (pill bugs- Isopods)
Crustaceans differ from other arthropods
in two ways:
1. 2pr of antenna; all others one or
none
2. Biramous appendages (primitive condition)
-basal protopod from which an endopod
and exopod arise
-condition seen in some appendages
of present day adults
GENERAL CHARACTERISTICS
1. Specialized respiratory organs --->gills
2. Lack Malphigian tubules
3. 16-20 segments: -increased tagmatazation
-major tagma; head, thorax, abdomen;
in crustaceans this varies but most commonly
cephalothorax/abdomen
4. Carapace- protective exoskeleton
Class Malacostraca- largest crustacean
class (shrimp, lobster. . . ) ("soft shell") 13 orders
**most common for us: Isopoda- pill bugs
Decapoda
- 5pr legs, first is chelae, pinchers, (cray., lobster)
Appendages: 1st antenna (uniramous)
2nd antenna
(uniramous)
3rd-5th,
mouth, maxillae, food handlers
3rd
pair mandibles- chewing grinding
5th
scaphognathite- (bailer), circulate water
6th-8th,
maxillipeds
9th-13th,
pereiopods, adapted for walking,
1st
pair are cheliped (pincher)
14th-18th,
swimmeretes
19th uropods,
telson bears anus
ENDOCRINE SYSTEM- ecdysis (molting)
-endocrine functions closely tied to nervous
function
-neurosecretory tissues
X-organ- located in eye stalk
Y-organ- located at base of maxillae
**both control ecdysis
molt occurs most frequently in juvenile
stages
X-organ produces molt inhibiting
hormone: Target, Y-organ
Y-organ releases ecdysone which
leads to molting
*certain conditions control release,
usually complex and species specific:
include nutritional state, temp.,
and photoperiod
*Androgenic glands- in cephalothorax of males (females never mature)
-promote development of testes
and male characteristics
-removal of androgenic gland --->
male develops female char.
-androgenic gland into female --->
develop male charac.
Other functions controlled by hormones:
-development of brooding structures
in females
-seasonal regulation of ovarian
function
-regulation of heart rate (eye stalk
hormones)
-regulation of color (eye stalk
hormones)
DIGESTION
Predaceous and filter feeders, scavengers
2part stomach
1st- cardiac stomach- large
contains gastric mill which grinds up food
2nd- pyloric stomach- filters
smaller particles into intestine
Digestive gland ---> empties
digestive enzymes into stomach
RESPIRATION
Gills -located in branchial
gill chamber
-separated from main body cavity
by lateral body wall, protected by carapace
-attached to bases of appendags,
aids in ventilation
-bailer drives water through
chamber
CIRCULATION
-open system w/heart
-blood into sinuses, circulated by body
movements
-clotting agent prevents loss of blood
NERVOUS SYSTEM- annelid type; dorsal
brain- ventral nerve cord
-ganglia from nerve cord in each segment
-sensory organs well developed
-compound eye (similar to insect) detect
motion, polarized light bright vs. dim
*in crustaceans located on eye
stalk
*visual field can be as large as
200o arc (no eye movement)
*crayfish have from 25-15,000
ommatidia
ommatidia- fused, outer
surface of each is a lens, below lens ---> crystalline
cone lens and cone gathers
light
rhabdom- convert light
energy to nerve impulse
pigment cells- prevent
light striking one rhabdom from reflecting into
adjacent ommatidium
statocysts- base of
first antenna, contains setae, provides info regarding
movement, orientation w/
respect to gravity and vibrations
REPRODUCTION- (widely varied)
-w/ exception of barnacles, crustaceans
are dioecious, eggs generally hatch into
juvenile that resembles adult (crayfish)
-Nauplius larva- primitive larval
form which must molt several times before assuming
adult form
-mating occurs after female molts, male
deposits non-flagellated
sperm near female gonadoducts,
eggs fertilized as they are shed.
Subphylum Uniramia
- contains insects
Class Chilopoda- centipedes
Class Diplopoda- 2prs of legs per segment,
millipedes
*hydrogen cyanide repellent, usually
caustic to organism
-not stored as hydrocyanide, precursor
united w/enzyme as it is expelled from body.
-increases chances of predator dropping
and never messing w/one of those again!
ENTOMOLOGY- Study of Insects
Class Insecta- largest and most
successful arthropod class
-three tagmata; head, thorax, abdomen
-abdominal appendages missing or reduced
-one pr. antenna
-respiration by body surface, tracheal
systems, gills in aquatic larva
-3 pr. of legs and usually 2pr of
wings (varied)
-highly adaptable- flight, well protected
egg, water extraction and retention
**evolution of flight maybe most important adaptation
-locomotion- walking, running (cockroach
up to 5 km/hr), jumping (flea, cocked leg,
muscle release, jump ~100X its own
length. If humans could do that we could long
jump ~600 ft.!!!)
FLIGHT
origins- wings from flaps originally
used to protect legs and spiracles. Later used to
glide from top of tall plants to
forest floor. Ability to flap, tilt and fold back came later
Direct (synchronous flight mechanism)
-downward thrust of wing due
to muscles acting on the base of the wing
-upward due to muscles attaching
dorsally and ventrally on the exoskeleton
Indirect (asynchronous flight mechanism)
-muscles act to change shape
of exoskeleton for both upward and downward
strokes
-upward- dorsal/ventral contract
(longitudinal relax)
-downward- longitudinal contract (dorsal/ventral relax)
Asynchronous because there is
no one to one correspondance between nerve
impulse and wing beat.
NUTRITION AND DIGESTION
-mouth parts: biting/chewing; piercing/sucking;
sponging
-digestive system past mouth somewhat
similar to previous groups
*foregut (mouth/salivary glands)
--->esophagus ---> crop ---> gizzard ---> midgut
(stomach, gastric ceca) --->
hind gut (intestine, anus)
Phytophagous- feeding on plant
juices and tissues
Saprophagous- feed on dead
Predaceous
Parasitic- fleas, lice
Insects parisitized by other insects- Hyperparasitism
GAS EXCHANGE- tracheal system,
spiracles- openings to outside of body, trachea
are tubes that carry oxygen to tissues
requiring oxygen, efficient system w/no
respiratory pigments
EXCRETION- malphigian tubules
, organs that excrete metabolic wastes in form of
urine while conserving body fluids
REPRODUCTION- one reason for their
success is their high reproductive potential.
Reproduction in terrestrial environments
is risky
Requires highly evolved coplatory
structures; requires mechanism to bring male and
female together at appropriate times
-internally controlled by endocrine system and reproductive organs
-externally controlled by quantity
and quality of food, photoperiod, population density,
temp., humidity
-stimuli- tactile, pheromones, visual, auditory
Metamorphosis
-development in egg can lead to differing results from the adult plan
-after birth (hatching) many insects
will need to change from an immature larval form to
something resembling adult
-post embryonic development differs widely
in insects; stages between molts = instars,
# of instars generally species specific
1. Ametabolous insects- no metamorphosis,
hatch directly from egg to a form
resembling miniature adult
Stages: egg ---> juvenile ---> adult
Silverfish, springtails
2. Hemimetabolous (Paurometabolous) insects- gradual or imcomplete metamorphosis
-young emerge from egg generally
resembling adult but with a disproportionatly
large head and w/o wings
Emergent form ---> nymph
-In grasshoppers 5 molts (instars)
from nymph to adult w/ gradual development of
wings and proportionate devel.
of head and body
Stages: egg ---> nymph ---> 5 instars ---> adult
Grasshoppers, cicada, cockroach
**aquatic hemimetabolous are
adapted to aquatic way of life, emerge as naiads
w/ gills and no wings
Dragonflies, mayflies
3. Holometabolous insects (complete metamorphosis) ~88% of all insects
-separate and distinct physiological
stages
-growth stage (larva), differentiation
stage (pupa), reproductive stage (adult)
**none of these stages compete
with each other for resources
Therefore, less competition, greater
chance of survival
Stages: egg ---> hatches into wormlike, segmented larva.
Larva feeds, grows and
undergoes several molts, final molt
transforms into --->
Pupa; stationary, non-feeding.
Appears externally to be inactive, however, internally
radical changes taking place.
Groups of undifferentiated cells
(embryonic cells called imaginal discs) resume
development
When adult fully formed case is ruptured and adult emerges
EX. beetles, flies, bees/wasps, butterflies / moths (crysalis vs. cocoon)
Diapause- period of dormancy to avoid periods of unfavorable conditions
COMMUNICATION
Mechanical: -sound production/reception
-visual signals
(bioluminescence) species specific flashing patterns,
luciferin/luciferase
reaction
-tactile- tapping, antenna
Chemical: Pheromones
- chemicals released by animals that cause behavioral
or physiological changes
in another member of the same species.
1. sex pheromones-
Excite or attract members of opposite sex; accelerate
or retard sexual maturation
2. caste regulating pheromones
- used by social insects to control the
development of individuals
in a colony
Ex. the amount of "Royal
jelly" fed to a female bee larva determines whether
it will be a queen or
a worker.
3. aggregation pheromones
- produced to attract individuals to feeding or
mating sites.
4. alarm pheromones
- warn other individuals of danger; may elicit an attack
or flight
Ex. when one is stung by a bee others are alarmed and likely to attack
5. trailing pheromones
- laid down by foraging insects to help others locate food
(ants)
SOCIAL BEHAVIOR- usually different
members of a colony are specialized for performing
different tasks
-highly developed in bees, ants, wasps,
termites
-each kind of individual belongs to
a caste; often three different castes present:
1. Reproductive females --->
queen
2. male/female workers, involved in support, protection and maintenance of a colony
3. Reproductive males ---> drones
Castes regulated by pheromones released by queen
Social behavior includes concepts of altruism and kin selection