1. SUBPHYLA: TRILOBITA, CRUSTACEA, CHELICERATA, AND UNIRAMIA
ARTHROPODS
SUBPHYLA: TRILOBITA, CRUSTACEA, CHELICERATA, AND UNIRAMIA

2. Phylum Arthropoda “jointed feet”
Characteristics:
segmentation
Jointed, paire appendages
Exoskeleton – chitin
Cephalization
Compound eyes
Coelom
Open circulatory system
Ventral nerve cord

3. The Exoskelton
The exoskelton is composted of the polysaccharide chitin. An arthropod can not grow without periodically shedding the exoskeleton. This process is called molting or edcysis. During the few days following the replacement of the exoskeleton, the animal is extremely vulnerable and must hide from predators. There is also the problem of desiccation.

4. Advantages & Disadvantages of the Exoskelton
Protection
Support
Site for muscle attachment
Flexible at the joints
Disadvantages
Heavy
Must be molted

5. Subphylum Trilobita
All members of this phylum are extinct

6. Subphylum Crustacea
Only arthopods with 2 pair of appendages on their head that serve as feelers
Most have segments which are fused into several tagmata
Most have gills for respiration
Most have a free-swimming larva called a nauplius

7. Crustacean Diversity

8. Subphylum Chelicerata
Have piercing and sucking mouth parts called chelicerae

9. Class Arachnida Include: spiders, scorpions, mites and ticks
Cephalothorax and abdomen
Cephalothorax – 6 pairs of jointed appendages
1 pair of chelicerae (used to inject venom into prey)
1 pair of pedipalps (holding food, chewing, & reproduction
4 pairs of walking legs
8 simple eyes at anterior end

10. Abdomen Spinnerets Respiration Excretory organs Book lung
Tracheae and spiracles
Excretory organs
Malpighian tubules
Coxal glands

11. Mites and Ticks Most abundant and specialized archnids
Completely fused head and cephalothorax

12. Subphylum Uniramia Classes Insecta Diplopoda Millipedes
2 pair of legs on each body segment
Rounded bodies
Poor vision with a good sense of smell
Feed on plants or decaying plant matter
Secrete a noxious fluid that contains cyanide when threatened

13. Chilopoda
Flattened bodies with one pair of legs per segment ( except first and last 2 segments)
May have 15 – 175 pairs of legs
The appendages on the first segment are modified into a pair of poison claws
Long antennae and two clusters of simple eyes
Move quickly and feed mostly on earthworms and other insects