Download Phylum Arthropoda - Bakersfield College

Kingdom Animalia
Subkingdom Eumetazoa
Bilateria
Phylum Arthropoda
Professor Andrea Garrison
Biology 3A
Illustrations ©2014 Cengage Learning unless
otherwise noted
Phylum Arthropoda
• Insects, spiders, crabs,
millipedes, centipedes, etc.
(arthron = joint; podos =
foot)
• Largest animal phylum
(>3/4 all species)
• All habitats
• Triploblastic
• Protostomes
• Bilateral w/cephalization
– Sensory structures
• Antennae, compound and/or
simple eyes, sensory hairs,
auditory organs, statocysts
Ecdysozoa; photo http://www.cdc.gov/dpdx/trichinellosis/
2
Hard Exoskeleton
• Chitin w/varying amounts of
calcium carbonate
• Muscles attached to inside of
exoskeleton
• Molt to grow
– Develop soft exoskeleton under
the old exoskeleton
– Shed old exoskeleton
– Aquatic
• Swell with water, then
exoskeleton hardens
– Terrestrial
• Swell with air then exoskeleton
hardens
– Vulnerable to predators until
new exoskeleton hardens
Arthropoda; photo by A. Garrison
3
Segmented Body
• External joints allow movement
• Tagmosis
– Segments fused or grouped
together in body regions
• May be covered by carapace so you
don’t see segments (can count
appendages)
– Segments within a region are
similar
– Segments differ between regions
• 1 pair appendages/segment
• Appendages may vary in
function
– Feeding, defense, walking,
swimming
Arthropoda
4
Body Regions
• Head
– Brain
– Sensory structures
• Eyes (compound or simple)
• Touch, chemical, hearing
– Feeding appendages
• Thorax
– Walking or swimming
appendages
– Some with wings
• Abdomen
– May or may not have
appendages
Fir0002/Flagstaffotos
Arthropoda; top photo by Didier Descouens; ,://creativecommons.org/licenses/by-sa/3.0/deed.en’
bottom photo by Fir0002/Flagstaffotos
5
Body Regions
• Some body regions may
be fused
– Cephalothorax
• Head and thorax fused
– Abdomen
Arthropoda
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Phylum Arthropoda
• Coelomate
• Complete digestive
system
– Head appendages
modified as mouthparts
• Open circulatory system
– Hemocoel fills with
hemolymph
• 2 ventral nerve cords
with ganglia
– Attached to nerve ring
around mouth w/ “brain”
Arthropoda
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Phylum Arthropoda
• Respiratory system
– Aquatic
• Gills
– Terrestrial
• Book lungs
• Trachea
• Excretory system
– Aquatic
• Paired glands at base of antennae
– Terrestrial
• Malphigian tubules joined to gut
• Reproductive system
– Dioecious
– Internal fertilization
– Several stages of development
between molts
• Successive stages may be similar
or abruptly different
Arthropoda
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Phylum Arthropoda
• 5 subphyla
– Trilobita
– Chelicerata
– Crustacea
– Myriapoda
– Hexapoda
Arthropoda
9
Subphylum Trilobita
•
•
•
Trilobites (tri = three; lobos = lobe)
All extinct
Lots of fossils
– Arthropods first organisms with hard
parts, molt several exoskeletons
•
3 lobes of body
– 1 median lobe, 2 lateral lobes
•
•
•
Dorsoventrally flattened
Heavy exoskeleton
3 body regions
– Head
•
•
sensory antennae
compound eyes
– Thorax w/appendages
– Abdomen w/appendages
– Appendages on thorax and abdomen all
similar
Arthropoda
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Subphylum Chelicerata
• Horseshoe crabs, spiders,
scorpions, mites, ticks (chela =
claw; keras = horn)
• Marine, freshwater, few terrestrial
• Predators or parasites
• Cephalothorax
– 6 pr appendages
• 1 pr chelicerae—pincers to assist in
feeding
• 1 pr pedipalps—grasping, sensory,
walking (pincers in scorpion to right)
• 4 pr walking legs
• Abdomen
– May have appendages
Arthropoda
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Subphylum Chelicerata
• Class Merostomata
– Horseshoe crabs
– Very ancient, primitive group
– Nocturnal feeder
• Worms, molluscs
– Compound and simple eyes
– Carapace covers cephalothorax
• 1 pr chelicerae
• 5 pr walking legs
– Abdomen
• 6 pr swimming appendages
• Book gills
– Telson
Arthropoda
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Subphylum Chelicerata
• Class Arachnida
– Spiders, scorpions, mites,
ticks
– Cephalothorax
• Simple eyes may be image
forming
• 1 pr chelicera
• 1 pr pedipalps
• 4 pr walking legs
– Abdomen
• No appendages
– Spinnerets exception to
this
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Subphylum Chelicerata, Arachnida
• Spiders
– Active hunters or spin webs to
capture prey
• Spinnerets on abdomen
• Liquid silk hardens on contact with
air
• Mites
–
–
–
–
–
Tiny
Cephalothorax and abdomen fused
Agricultural pests
Mange
Dust mites cause allergies
• Ticks
– Blood-sucking ectoparasites
– Cephalothorax and abdomen fused
– Transmit bacterial pathogens
• Rocky Mountain spotted fever
• Lyme disease
Arthropoda
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Subphylum Crustacea
• Shrimps, lobsters, crabs
(crusta = crust, hard shell)
• Marine, freshwater, very
few terrestrial
• Most with cephalothorax
and abdomen, but some
with all three body regions
• Tagmosis well developed
– Different regions with
different functions and
different appendages related
to function
• Walking vs swimming
Arthropoda
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Subphylum Crustacea
• Cephalothorax
– Often covered by carapace
– 5 pr appendages on head
• 2 pr antennae
• 3 pr mouthparts
– 1 pr mandibles
» Bite, chew
– 2 pr maxillae
» Pass food to mouth
– More appendages on
thorax and abdomen
• Decapods
– 5 pr legs on thorax
Arthropoda
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Subphylum Crustacea
• Well-developed nervous
system
– Large ganglia
– Antennae with chemical
and touch receptors
– Compound eyes
– Statocysts on head
– sensory hairs in
exoskeleton
• Respiration
– Gills under carapace
• Excretion
• Antennal gland
Arthropoda
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Subphylum Myriapoda
• Centipedes and millipedes (myrias
= ten thousand; pod- = feet)
• Terrestrial
– Under rocks, leaves
• 2 body regions
– Head
• 1 pr antennae
– Segmented trunk
• Centipedes
– 1 pr walking legs/trunk segment
– Predators
• Invertebrates and small vertebrates
• Powerful toxins
• Millipedes
– 2 pr walking legs/trunk segment
– Feed on decaying leaves, organic
matter in soil
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Subphylum Hexapoda
• Insects (hex = six; pod- =
feet)
• Most successful animal
group
– Every habitat
– Wings
• Cross environmental
barriers, disperse
– Wingless groups
• not as successful as
winged groups
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Subphylum Hexapoda
• 3 body regions
– Head
• 1 pr compund eyes
• 2-3 simple eyes (ocelli)
• Mouthparts
–
–
–
–
1 pr antennae
1 pr mandibles
1 pr maxillae
1 labium & 1 labrum cover
mouthparts
– Mouthparts vary with feeding
style of insect
– Thorax
• 3 pr legs
• 2 pr wings in most
– Abdomen
• No walking legs
• Appendages for copulation
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Subphylum Hexapoda
• Respiration via tracheal
system
– Spiracles open into system
– Tracheal tubes extend to
tissues
• Excretion via Malphigian
tubules
– Carry nitrogenous wastes
to intestine to be released
with feces
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Insect Development and Ecdysis
• Developmental stages beyond the egg called
instars
• 3 types of development
– No metamorphosis
• All instars look like mini-adults
– Incomplete metamorphosis
• Only minor differences with each instar
• Early nymphs lack wings
– Complete metamorphosis
• Drastic changes with each instar
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Insect Development and Ecdysis
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Insect Development and Ecdysis
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Insect Development and Ecdysis
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