1. Jointed-legged invertebrates
Arthropods
Jointed-legged invertebrates

2. Arthropod Characteristics
Metamerism with tagmatization
Chitinous exoskeleton
Paired-jointed appendages
Growth with ecdysis (molting)
Ventral nervous system
Open circulatory system
Complete digestive tract
Malpighian tubules for excretion

3. Evolutionary Significance
Protostomes
Schizocoelous development
Paired ventral nerve cord
Loss of internal metamerism
Increased tagmatization (specialization of segments)

4. Terrestrial Dominance
Minimize water loss
Exoskeleton
Respiratory system development
Advanced excretory system
Greater ability for movement
Exoskeleton attaches strong muscles
Support

5. Exoskeleton Major reason for success of this group! Provides Support
Protection
Prevention of dehydration
Sites for muscle attachment

6. Exoskeleton Structure
Epicuticle (outer layer)
Water tight
Barrier
Procuticle (inner layer)
Made of chitin
Allows for protection
Forms joints

7. Ecdysis Shedding or molting of exoskeleton New exoskeleton is soft
Tanning (sclerotization) must take place to make outer layer of procuticle hard

8. Metamorphosis
Change in body form from immature (larval) stages to adult forms
Reduces competition between stages for
Food
Living space
Larval forms often occupy different habitats than the adults do

9. Taxonomy of Arthropods
4 subphyla
Trilobitomorpha (all extinct)
Chelicerata
Crustacea
Uniramia

10. Trilobitomorpha
Trilobites
All extinct
All marine
3 sections

11. Chelicerata Class Merostomata Class Arachnida
Horseshoe crabs
Water scorpions (eurypterids)
Class Arachnida
Spiders
Mites
Ticks
Scorpions
Class Pycnogonida (sea spiders)

12. Chelicerate Characteristics
Two-part body
Opisthosoma
Chelicerae (1st pair of appendages – forms feeding palps or fangs)
Pedipalps (2nd pair of appendages)
Cephalothorax (prosoma)
Book lungs or book gills

13. Crustacea Class Malacostraca Class Branchiopoda
Shrimp, lobsters, crayfish
Isopods (wood lice – roly poly)
Amphipods
Class Branchiopoda
Fairy shrimp, brine shrimp
Water fleas

14. Class Copepoda Class Cirripedia Cyclops (freshwater) Barnacles
Sacculina – parasite of crabs

15. Crustacean Characteristics
2 pairs of antennae
Biramous appendages (Y-shaped)
Segments are serially homologous

16. Uniramia Class Diplopoda (millipedes) Class Chilopoda (centipedes)
Class Pauropoda
Class Symphyla
Class Hexapoda (insects)

17. Insect Locomotion Flight Walking (3+ legs on ground at all times)
Running (Can run on 2 legs)
Swimming (legs modified as paddles)
Jumping (saltatory locomotion)

18. Insect Respiration & Circulation
Tracheae & spiracle system
Circulation
Modified open circulatory system
Some vessels
Primitive Heart

19. Nervous System Johnston’s organs (hearing - on antennae)
Tympanic organs (hearing – on legs or body)
Compound eyes (facets – ommatidia – fused)
Simple eyes (ocelli)

20. Metamorphosis Type Appearance Young called Ametabolous
larvae look like adults, just smaller
instars
Paurometabolous
Specific number of molts
Nymphs (land)
Naiads (water)
Holometabolous
Young very different from adults
Larvae

21. Economic Impact of Arthropods
Name one effect each major group has on mankind (good or bad).
For insects, list 4 good things that they do and 4 bad things that they are responsible for.