Phylum Arthropoda
 Read Chap 31 pgs. 681-703
 Dichotomous Key
What is Entomology?
The study of insects
(and their near relatives).
Species Diversity
PLANTS
INSECTS
OTHER
ANIMALS
OTHER
ARTHROPODS
Arthropods
Jointed-legged
invertebrates
 CLASSIFICATION
 (LEARN EXAMPLES OF EACH CLASS)
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SUBTrilobita
PHYLUM
CLASS extinct
ORDER
Crustacea Chelicerata
Crustacea
Arachnida
Uniramia
Chilopoda
Diplopoda
Insecta
16
Characteristics of
Phylum Arthropoda
- Segmented bodies are arranged into regions,
called tagmata (in insects = head, thorax,
abdomen).
- Paired appendages (e.g., legs, antennae, wings)
are jointed.
- Possess chitinous exoskeleton that must be shed
during growth.
- Open circulatory system
Head Thorax Abdomen
-
Nervous system is ventral (belly) and the
circulatory system is open and dorsal (back).
Complete digestive system
Exoskeleton
Major reason for success!
Provides
Support
 Protection
 Prevention of dehydration
 Sites for muscle attachment
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Metamorphosis
Change body form from immature
(larval) stages to adult forms
Reduces competition between
stages for
Food
 Living space
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Taxonomy of Arthropods
4 subphyla
Trilobitomorpha (all extinct)
The state fossil of Ohio
 Chelicerata
 Crustacea
 Uniramia
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Subphylum
Chelicerata
(plier like)
Horseshoe crabs
Spiders
Mites
Ticks
Scorpions
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Scorpion
Scorpion Anatomy
Scorpion Head
chelicerae
eyes
pedipalp
Orders of Arachnids
Pseudoscorpion
Tick
(a mite)
Scorpion
Daddy-long-legs
Wolf
Spider
Pseudo scorpion
(pseudo means “false”)
Mite and Tick Body Regions
pedipalps &
chelicerae
cephalothorax
abdomen
Common
ticks
American dog tick
male
-Vectors
Rocky mountain
spotted fever
Blacklegged (deer)
tick female
- Vectors Lyme
disease
American dog tick female laying egg mass (1000-2000 eggs!).
Mites
Clover mites
Twospotted spider mites
Velvet mite
Predatory mite
Phalanges
(daddy-long-legs)
cephalothorax
abdomen
Spider Anatomy
pedipalp
chelicera (fang)
cephalothorax
narrow waist
abdomen
Jumping Spider
Abdomen
Cephalothorax
Chelicera (fang)
Pedipalp
Wolf spider with egg case
Tarantula
Spitting spider
Orbweaving spider
Dangerous
Spiders
Black widow with egg case
Brown recluse
(fiddleback)
Interesting modifications
 Spinnerets
 Malpighian tubules
Subphylum
Crustacea
Shrimp, lobsters, crayfish
 Fairy shrimp, brine shrimp
 Water fleas
 Barnacles
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Crustaceans
Crayfish
cephalothorax
(Decapoda)
Sow bug
(Isopoda),
a terrestrial
crustacean
CLASS CRUSTACEA
tremendous variety
 daphnia, crabs, lobster, pill bugs, crayfish
 *primarily aquatic, mostly marine 25,000
species
 (motile sessile microscopic, 2 ft. or more)
 *gills, at least 5 pairs of legs
 *carapace- shield to protect vital organs
 * branched antennae
 see lab for specifics of this group
Subphylum Uniramia
Class Diplopoda
(millipedes)
Class Chilopoda
(centipedes)
Class Hexapoda (insects)
[one pair of antennae, head & trunk regions, trunk with many pairs of legs]
Diplopod (Millipede)
Two pair of legs per visible segment, attached
under body.
Chilopod (Centipede)
Pair of fangs under head, one pair legs per visible
segment - attached to side of body.
Symphyla (Symphyla)[garden centipede]
No fangs, no eyes, legs attached to side of body.
Millipede (Diplopoda)
Centipede (Chilopoda)
Garden centipede (Symphyla)
Nervous System
Johnston’s organs (hearing - on
antennae)
Tympanic organs (hearing – on legs
or body)
Compound eyes (facets –
ommatidia – fused)
Simple eyes (ocelli)
Economic Impact of
Arthropods
1. Name two effects of each major
group has on mankind (good and bad).
Crustacea, Millipede, Centipede, Arachnida
2. For insects, list 4 good things
that they do and 4 bad things
that they are responsible for.
Insects
Head Thorax Abdomen
How Many Kinds Insects
are there in the world?
• 1,000,000 species known
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Possibly 3,000,000 unidentified
species
Classification of Japanese
Beetle
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Kingdom
Phylum
Class
Order
Family
Genus
Species
Animalia
Arthropoda
Insecta
Coleoptera
Scarabaeidae
Popillia
japonica
*molting "ecdysiast"hormone induced changes to create
new and larger exoskeleton
desiccation potential
 "instars" periods between molts
vulnerable while exchanging skeleton
may continue throughout life or end
at a particular point
DIGESTION
 foregut
 ingestion, mechanical breakdown and storage
 midgut
 chemical digestion, absorption, enzymatic,
 (sounds like our intestines)
 hindgut
 absorption of water and formation of feces
RESPIRATION
(handout in binder )
Open Circulatory System- blood not confined to the vessels
 Pericardial sinus- space for gas exchange around
the heart (open space)
 Gases into the body through the spiracles in the
exoskeleton (waxy)
 Trachae- tubes from spiracles to vital locations
 ***blood is not vital for gas exchange*** rare to
find hemoglobin
 Tracheoles- branches with membranes at the end
fluid tipped perhaps
other possible modifications
 *book lungs- look like corrugated cardboard
 *coordination between opening and closing of
spiracles to pump the air in (think of a tire pump)
 *air sacs at the end of the tracheoles for increased
surface area
 *gills
 BEHAVIOR IN THE PHYLUM
ARTHROPODA
 (insects mostly) video Swarming Hordes
 Communication
 Chemical, visual, and auditory
Communication
*chemical
Pheromones- airborne chemicals are used by
males can find females for mating purposes
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1) releasers- immediate behavior change
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2) primers- profound physiological
changes
Bug’s Life
 humans have exploited this with bug traps
(June bugs)
 Scent trails can be left on the ground
during food foraging trips (A BUG’S Life
video)
 plants mimic scents to attract pollinators
 death pheromones- remove ant from a
colony and paint with the chemical, return
to colony and is repeatedly carried away.
 0.00000001 grams silkworm female can
be detected 2 miles
Communication
*visual can see ultraviolet wavelengths of light
 Fireflies use light to attract mates Males are
in the air while females remain on the ground
Communication
 *Sound
 production in grasshoppers, crickets and
cicadas
 scraping of limbs on the exoskeleton, air
vibrations along the exoskeleton caused by
muscle movement
Mimicry
 visual, camouflage (hide or lie in ambush)
 SOUNDS CAN ALSO BE MIMICED
 (faked you out!)
 Now you’re dinner!
SOCIAL BEHAVIOR
requires communication
 A colony can have the same effect as a large
single animal
 Hey, hey, hey do what I tell you
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 Division of Labor
 ex. bee hive
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80,000 members
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polymorphic anatomy
 Drone
Worker
Queen
What a life?
 worker 6 wk. life, sterile female,
reproductive organs become stinger, 1,000 s
 drone- (n) reproductive male, only for
mating, 100s, die after mating, killed if food
is low
 queen bee- reproductive female, 5-6 year
life
worker behavior
 week 1
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feed queen, drones, larva, secrete "royal jelly"
 weeks 2-4
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secrete wax, clean, repair hive, guard,
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fan in fresh air
 weeks 5-6
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gather pollen and nectar
Stand for the QUEEN!
 QUEEN is like other female
but she eats "ROYAL
JELLY"
 Secretes "queen factor"
which prevents other females
from becoming reproductive.
Mates once and stores sperm
Butt wiggle dance
Metamorphosis
Incomplete grasshopper and termite
 Egg- nymph- adult
 Immature adult look alike,
small ,non-sexual
Metamorphosis
 Complete
 butterfly, moth (most insects)
 Egg-larva-pupa- adult
 CACOON
 OR CHRYSALSIS
 Controlling factors
 Sequential expression of genes
 Brain hormone stimulates molting hormone
in thorax gland
Molting hormone released in both where
juvenile hormone is present
 JH
 JH
 JH
MH larva molts
MH larva pupates
MH pupa to adult
 Importance of metamorphosis?
 No competition for food
 What the caterpillar eats the adult does not
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Name ________________________ Period ________
CRAYFISH EVALUATION LAB
Materials
1 lab set “Dissecting a Crustacean- the Crayfish”
Dissecting microscope
Dissecting tools
STEP 1Examine the external anatomy of a crayfish
Follow Procedure A of the LAB NOT STEP 5 ON LIVE CRAYFISH
Compare the live specimens w/ diagrams on sheets
Describe texture of the crayfish
STEP 2Test Crayfish Behavior
Lay live crayfish in a clear plastic container
Observe/record behavior for 4-5 minutes
Observe/record movements (O/R)
O/R responses to stimuli on a table with 2 columns (see below)
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Bubbles gently blown into the water
Touch with a probe (Anterior/ Posterior)
Touch chelipeds, walking legs, middle of dorsal, telson
Darken ½ of the container
Shine a light on the anterior
5. Drop one piece of food (shrimp pellet) near the anterior O/R feeding behavior
STEP 3 Crayfish Dissection
Follow instructions in the lab papers.
STEP 4
Reading Assignments
715-719, 720-734
EXAMPLE
Stimulus
Response
Probe
telson
walking leg
Rules for writing a
dichotomous key
 1. always couplets
 2. total number of couplets is one less than
the total number of items
 3. no overlapping measurements
 4. only physical descriptions (no behaviors)
 5. start couplets with the same word
Test Topics
 Dichotomous Key, Video “Swarming Hordes”,
Arthropod Notes,
 Lab Crayfish dissection and Behavior, Insect
Social Behavior,
 SEQUENTIAL COMPARISON INDEX,
relationship between annelids and arthropods,
Read (general 715-719, crustacea729-734)
Chap 31 in regular BIOLOGY text