Phylum Arthropoda is the most successful animal group and includes insects, spiders, crustaceans, and others. Arthropods have jointed appendages, a segmented body, and an exoskeleton. They display a variety of traits including bilateral symmetry, an open circulatory system, respiration through structures like books lungs or tracheae, and reproduction involving separate sexes. Major subgroups include chelicerates like spiders, crustaceans like crabs and lobsters, myriapods like centipedes and millipedes, and insects, which display the greatest diversity and are the most terrestrial.

1. Phylum ARTHROPODA
The most successful animal group to
have ever lived

2. Phylum Arthropoda
 ARTHRO (joint) + PODA (foot)  have
jointed feet
 jointed appendages (legs & other
outgrowths)
 chitinous exoskeleton for protection,
but restricts size  MOLTING
 bilateral symmetry, triploblastic,
coelomate

3. Phylum Arthropoda
 body segmented  forming specific
body regions

4. Structure and Function
 Feeding – complete digestive tract
 Internal transport – open circulatory
system w/ dorsal heart
 Respiration – varied
 Excretion – varied
 Nervous system – brain + ventral nerve
cord; sense organs (sight, smell,
hearing, balance, taste, touch, etc.)

5. Structure and Function
 Reproduction – sexes separate

6. Taxonomy of
Phylum Arthropoda
 Subphylum TRILOBITA
 Subphylum CHELICERATA
 Subphylum CRUSTACEA
 Subphylum UNIRAMIA
 Class CHILOPODA
 Class DIPLOPODA
 Class INSECTA

7. Subphylum TRILOBITA
 early arthropods  all extinct
 pronounced segmentation
 little or no variation in appendages

8. Subphylum CHELICERATA
 CHEILOS (lips) + CHEIR (arm)
 cepalothorax & abdomen
 no antennae
 6 pairs of appendages:
chelicerae – claw-like, for feeding (pincers or
fangs)
pedipalps – sense chemicals, touch; for holding
food, sperm transfer in males
walking legs – 4 pairs

9. Subphylum CHELICERATA
 respiration: book lungs
 e.g. spider
scorprion
tick & mite
horseshoe crab

10. Subphylum CRUSTACEA
 two pairs of antennae
 cephalothorax & abdomen
 most marine, some freshwater; few
terrestrial
 e.g. lobster, crab, shrimp
waterflea, barnacle, crayfish

11. Structure & Function of the
Crayfish
 paired appendages: antennules, antennae,
maxillipeds, chelipeds, walking legs,
swimmerets, uropods
 capable of self-amputation & regeneration

12. Structure & Function of the
Crayfish
 excretion: green glands
 circulation & respiration: heart 
arteries  sinuses  gills
 sense organs: compound eyes,
antennules, antennae, statocyst
 reproduction: dioecious; fertilized eggs
attach to female s swimmerets…
young, too (for a while)

13. Subphylum UNIRAMIA
 one pair of antennae  uniramous
(unbranched)
 jaw-like mandibles for feeding
 compound eyes

14. Subphylum UNIRAMIA
Class Chilopoda
• w/ head & worm-like body made up of
similar segments
• segments have one pair of legs
• head w/ one pair of antennae & various
mouthparts
• e.g. centipede ( hundred legger )

15. Centipede

16. Subphylum UNIRAMIA
Class Diplodopa
• distinct head w/ worm like body
• two pairs of legs per segment
• head w/ one pair of antennae &
mouthparts
• e.g. millipede ( thousand legger )

17. Millipede

18. Subphylum UNIRAMIA
Class Insecta
• most successful class  most terrestrial,
capable of flight
• body regions: head, thorax & abdomen
• pair of antennae, several mouthparts,
3 pairs of walking legs + wings
• variations: mouthparts, body form, legs

19. Subphylum UNIRAMIA
• respiration: spiracles opening into
tracheae
• excretion: malpighian tubules
• metamorphosis:
incomplete (e.g. grasshopper, cockroach)
egg  nymph  adult
complete (e.g. butterfly, bee, fly, beetle)
egg  larva  pupa  adult

20. Incomplete
Metamorphosis

21. Complete
Metamorphosis

23. And the famousest of them all…