Arthropod Ancestors
Like annelids
True coelom
Segmented body
Fossils among the oldest and best
Ex: Trilobites
600 million years
Extinct
Once common in seas
Jointed appendages
Complex eyes 4
Arthropod Numbers
More than all other animals combined
> 1 million species
More kinds of beetles alone than there are vertebrates
Most small ~ 1mm (.003 in)
Some 3.6 m (about 12 ft)
Ex: spider crabs
6
Arthropod Characteristics
1) Jointed appendages
2) Segmentation
3) Distinct head
4) Exoskeleton
5) Many have wings
6) Open circulatory system
7) Malpighian tubules for
excretion
8) Respiration
Gills
Book lungs
Tracheae
7
1) Jointed Appendages
Appendage - Structure
that extends from the body
Used for:
Walking
Swimming
Sensing
Manipulating food
Chewing
Include:
Legs
Antennae
Mouth parts
8
Jointed Appendages
Bend
Can have 6 to 100s
Shaped like:
Rakes
Tweezers
Nutcrackers
Hammers
Paddles
9
Segmentation
Often exists only in larval stage
Segments fuse during development
Most have three distinct body regions
Head
Thorax (mid body region)
Abdomen
Some have cephalothorax = head and thorax fused
ex: crab p. 690
10
Distinct Head
Sometimes attached
to thorax forming the
cephalothorax
Contains:
Eyes
Brain
Antennae
11
Compound Eyes
Thousands of individual
units
Each has lens and
retina
Brain receives info from
each
Makes unclear image
See motion very quickly
Most arthropods have
12
Simple Eyes
Single lenses
Do not form images
Distinguish light and dark
Some arthropods only
have simple
Most have both simple and
compound
Ex: dragonflies’ and
locusts’ simple eyes
detect horizon
Help stabilize position in
flight 13
Exoskeleton
Skeleton on outside
Protection and muscle
attachment
Composed mostly of chitin
Linked sugars
Layered
Nonliving - cannot grow!
Tough but brittle
Thickness varies b/w groups
Thinner at joints = flexible
14
Molting = ecdysis
Shedding of exoskeleton
Controlled by hormones
New skeleton forms below
old
Larger than old
Old gets broken down by
enzymes and breaks open
Animal crawls out
Every surface is shed
Sometimes animal dies in
process
New is soft, but hardens
Arthropod molting 1.37.mp4 15
Respiration
In Terrestrial arthropods:
Tracheae
Fine network of tubes
Carry oxygen Valves control
Spiracles Openings in abdomen where
air enters
Spiders use book lungs
Leaf-like plates
Large surface area
Lobsters have gills – large surface area
16
6) Excretion
Terrestrial arthropods
Unique
Malpighian tubules
Finger-like structures
Attached to gut
Bathed in blood
Conserve water
Eliminate metabolic
wastes
18
Classification of Arthropods
Domain Eukarya
Eukaryotic cells
Kingdom Animalia
Multicellular
Heterotrophic
No cell wall
Phylum Arthropoda
Arthro = “Jointed”
Poda = “Feet/Appendages”
19
Two Basic Groups of Arthropods
1) Arthropods with jaws
Subphylum Uniramia (yoo nuh RAY mee uh)
Subphylum Crustacea
2) Arthropods with
fangs/pincers
Subphylum Chelicerata (kuh
LIS uh rahd a)
20
Subphylum Chelicerata
Largest class =
Arachnida
Mouthparts called
chelicerae (kuh LIS uh
ree) - modified into
fangs/pincers
22
Arachnida Characteristics
No antennae
Appendages
Chelicerae – 1 pair
Pedipalps – 1 pair
Walking legs – 4 pair
Two body regions
Cephalothorax
Abdomen
Joined by pedicel
24
My Goodness! So Many Eyes!
Most have 8 eyes
Arrangement varies
Identification
Vision varies
Hunters
Better vision
Web builders
Poor vision
25
My Goodness! Such Hairy Legs!
Hearing
Vibrations detected
by “Hairs”
Taste and smell
Organs on legs and
pedipalps
26
Spider Feeding
Important predators
Poison glands
Secrete toxin
through fangs
Kills or paralyzes
Injects enzymes
Digests tissues
Liquifies
Suck up food
27
Book Lungs - Respiration
Contain sheets of thin
plates
Blood filled
Air passes over them
Blood picks up oxygen
by diffusion
31
Dangerous Spiders – Brown Recluse
Called “fiddleback” or
“violin”
Violin-shaped marking on
top of cephalothorax
Six eyes
All arranged in pairs
33
Dangerous Spiders – Brown Recluse
Found in Midwest and Southern U.S.
Under rocks, logs, woodpiles, dirt, or debris
During cooler months, can find in house
Basements
Attics
Vents
34
Dangerous Spiders – Brown Recluse
Bite often not felt
Reaction depends:
Amount of venom injected
Victim’s body reaction to
venom
Wound
Deep
Sore
Long time to heal
35
Dangerous: Black Widow Spider
Many species in U. S.
Potent neurotoxic venom
Most venomous spider in N.
America
Female injects
Small dose
Rarely causes death
Human mortality < 1%
Usually found outside
Every state except Alaska
36
Black Widow Spider
Adult female = shiny and jet
black
Red hourglass marking on
bottom of abdomen
~ ½ inch long not including
the legs
Adult males = harmless
~1/2 female’s size
Black widow vs. Brown Recluse
3:19
37
Other Arachnids - Scorpions
Scorpions
Long slender abdomen
End of abdomen = venomous
stinger
Folded over body
Pedipalps = large pincers
Hold food
Reproduction
38
Other Arachnids
Most = small
Ex: mites, chiggers, and
ticks
Head, thorax, and
abdomen are all fused
Distributed throughout
world
39
Mites
Most not harmful
Some plant/animal pests
Some spread infections
Ex: Lyme disease spread by
deer ticks Symptoms include:
Fever
Headache
Fatigue
Characteristic “bulls-eye” skin
rash
Can be treated w/ antibiotics
40
Subphylum Uniramia
Class Insecta Kingdom Animalia
Phylum Arthropoda
Subphylum Uniramia
Mandibles
Class Insecta Life of Insects - Attenborough_ Life
in the Undergrowth 8 min
42
Insects by the Numbers:
Largest group of
organisms on Earth!
Mostly terrestrial
> 700,000 named
species
~80% of known
animals
New species
discovered every
day!
43
Insect Body Plan
Three body regions:
Head
Thorax
Abdomen
One pair of antennae
Three pairs of legs
Most have 2 pairs of
wings
44
Insect Structure – The Head
1 pair of compound
eyes
Some have simple
eyes
1 pair of antennae
Mandibles or modified
mouth parts
45
Insect Mouth Parts
Modified for different types of feeding
Piercing
Lapping
Sucking (proboscis)
Chewing
46
Insect Thorax
Three segments:
1st = (prothorax)
Middle = (mesothorax)
Last = (metathorax)
All have 1 set of legs
Wings may be present
Middle and last segment
Spiracles
Openings where air enters
On the middle and last segments
49
Insect Abdomen
Spiracles on each segment
Tympanum
Membrane
Hearing organ
Some insects
Female abdomen
Ovipositor
Deposits eggs
52
Complete Metamorphosis
Most ~ 88%
Four stages
1) Egg
First stage
2) Larva
Eating machines
Different foods than adults
Do not look like adult
Ex:
Caterpillars
Maggots
Grubs
3) Pupa
Do not eat
4) Adult 58
Incomplete Metamorphosis
~ 12%
Three stages:
1) Egg
First stage
2) Nymph
Look like small adults
No wings
Cannot reproduce
Eat same food as
adults
3) Adult 59
Insect Orders - Coleoptera
= “Sheath” “Wing”
Beetles
Chewing mouth parts
2 pairs of wings
First pair hardened into elytra
Protective
No veins
Second pair
Membranous
For flying
Complete metamorphosis
60
Insect Orders - Lepidoptera
= “Scale” “Wing”
Butterflies
Moths
Sucking mouth parts
2 pairs of wings
Covered with scales
Complete metamorphosis
63
Insect Orders - Diptera
= “Two” “Wings”
Flies
Mosquitoes
Only 1 pair of wings
Wings for flight
Halteres
Club-like structure
Behind wings
For balancing
Complete metamorphosis
67
Insect Orders - Hymenoptera
= “Membrane” “wing”
Bees
Wasps
Ants
Two pairs of wings
Abdomen w/ narrow waist
Only insects with “stingers”
Social insects
Complete metamorphosis
70
Insect Orders - Odonata
= “Tooth” Dragonflies
Damselflies
Large compound eyes
Antennae short; bristle-like
Two part wings
Incomplete metamorphosis Aquatic immatures
Naiads
73
Insect Orders – Odonata
Dragonflies Damselflies
Strong flying insects Weak flying insects
At rest – wings out from body Most hold wings along
length of abdomen
74
Insect Orders - Homoptera
= “Same” “Wing”
Cicada
Aphids
Leafhopper
Treehopper
Wings (if present) fold over back
Piercing and sucking mouth parts
Beak at base of head
Incomplete metamorphosis
77
Insect Orders - Hemiptera
= "Heteroptera"
“Half” “Wing”
True Bugs
Forewings both
membranous and hard
portions
Piercing and sucking mouth
parts
Beak at front of head
Incomplete metamorphosis 79
Insect Orders - Orthoptera
= “Straight” “Wing”
Grasshoppers
Crickets
Walking sticks
Mantids
Roaches
Chewing mouth parts
Leathery front wings
Hind wings fold like fan
Incomplete metamorphosis
82
Ephemeroptera
= “Wing for a day”
Mayflies
Adult stage of life cycle
is short
Few hours to days
Swarms
84
Insect Flight
May have been first
animals to have wings
Reach new food
Escape predators
Wings on thorax
Composed of chitin
Strengthened by veins
Most fold at rest
86
Insect Wings
Most = 2 pairs
One for flight and
other for protection
Diptera = 1 pair
Fleas and lice =
none
Halteres
Stability in flight
87
Social Insects
Live in colonies
Division of labor
Different individuals = different roles
Caste Role etermined by
Heredity
Diet
Pheromones
Examples Order Hymenoptera
Ants
Bees
Wasps
Isoptera Termites
Social Insect Video Clip
88
Subphylum Uniramia
Mandibles
Unbranched appendages
One pair antennae
Major groups
Insects
Centipedes
Millipedes
90
Centipedes - Class Chilopoda
One pair of legs per segment
Predators
Eat arthropods (mostly)
Pair of poison claws
Paralyze prey
Jaws are weak
Rarely penetrate human skin
Centipede vs. Mouse Video
clip
91
Millipedes - Class Diplopoda
Two pairs of legs per segment
Eat plant material
Coil up when disturbed
Defense:
Secrete stinky juice from pores along sides
92
Subphylum Crustacea
Domain Eukarya
Kingdom Animalia
Phylum Arthropoda
Subphylum Crustacea
Examples:
Crabs
Krill
Pill bugs
Shrimp
96
Crustaceans
“Insects of the sea”
Most abundant in
oceans
Nauplius
Distinctive larval
form
3 pairs of branched
appendages
Molts
97
Aquatic Crustaceans
Food source for humans
Key part of food chains
Part of plankton
Many small
Ex:
Daphnia
Copepods
Ostracods
Fairy shrimp
Krill
98
Krill - Euphausia superba
Shrimp-like
In all oceans
Zooplankton
Feed on phytoplankton
Swarm in large groups
Food for:
Baleen whales
Manta rays
Whale sharks
99
Decapods
Larger
Ex:
Shrimp
Lobster
Crabs
Crayfish
Five pair of legs
1/4 of crustaceans
Cephalothorax
Carapace
Protective shield 101
Crayfish Appendages
Chelipeds
Anterior pair of legs
Large pincers
Defense
Swimmerets
Abdomen
Small, leg-like
Swimming and
reproduction
102
Crayfish Appendages
Uropods
Flattened
Paddle-like
Side of tail
Telson
“Tail spine”
Tip of tail
Movement
See p. 690
103
Sessile Crustaceans
Hard plates open and close
Extend jointed, feathery
legs
Comb food from water
Hermaphrodites
Ex: Barnacles
Sessile as adults
Live on rocks, whales,
posts
106
Terrestrial Crustaceans - Order Isopoda
Only few
Pill bugs and Sow bugs
“Rolly-pollies”
“Wood lice”
Live in leaf litter
107
Isopod Features
3 body parts
1 prominent pair of antennae
7 pairs of legs
7 segments on thorax
Uropods on abdomen
Dark gray to white color
w/ or w/out pattern
108
Arthropods and Humans
Cause millions of $
of damage to crops
Use insecticides to
kill
Sometimes toxic to
other lifeforms
Sometimes don’t
break down;
accumulate =
biomagnification
110
New Pest Controls
Arthropod specific
neurotoxins
Insect traps and
physical barriers
Predators
Parasitic wasps,
ladybugs
GM plants
111