1. Phylum Arthropoda

2. External jointed skeleton (exoskeleton) with 2 layers:
Known for metamerism (body divided into segments)- each body region = tagmata
External jointed skeleton (exoskeleton) with 2 layers:
Epicuticle= Outermost waxy layer
Procuticle= Inner layer made of chitin which partially hardens
Exoskeleton molts (endysis) periodically so that arthropod can grow.
Internal cavity (hemocoel) with open circulatory system and internal organs
Metamorphosis (change in body form/physiology) often present; this reduces competition between larva and adult stages

3. Subphylum Chelicerata
Known for 2 tagmata:
Prosoma/cephalothorax = 1st body region which is a sensory, feeding, and locomotor tagmata.
***This region also includes legs (appendages). 1st pair of appendages are called chelicerae (used for feeding); 2nd pair are called pedipalps (used for used in feeding, locomotion, or reproduction)
Opisthosoma = 2nd body region which contains digestive, reproductive, excretory, and respiratory organs
Mostly carnivores
No antennae

4. Class Merostomata Horseshoe crabs (only 4 species living)
Mostly in Atlantic Ocean and Gulf of Mexico
Scavenge for annelids, molluscs, and other invertebrates
Last pair of appendages have leaflike plates for locomotion and digging
Opisthosoma contains book gills (gases exchange between blood and water)
Dioecious (female lays eggs which are fertilized by male)

5. Class Arachnida Malpighian tubules for excreting waste
Book lungs (similar to book gills)
Open circulatory system
Many sensory structures (sensilla) on body
Dioecious (often by spermatophore)
Most are oviparous (female lays eggs that develop outside body)
Others may be ovoviviparous (development internal with a yolky egg for nourishment) or viviparous (eggs that are nourished directly by female mother, live young are born)
Many care/tend to eggs and young
Digestion may be partially external as well as internal

7. Class Arachnida (cont.)
Order Scorpionida
Scorpions
Dancing-like courtship that is followed by ovoviparous or viviparous fetilization (young stay with mother on her back until 1st molt)
Order Araneae
Largest order: Spiders
Prosoma with poison glands and fangs
Pedipalps modified for sperm transfer
6-8 eyes (some species have well developed eyes for catching prey)

8. World’s Most Venomous Scorpions…
*In general, scorpions with slim and narrow pincers are equipped with more toxic venom. Powerful venom compensates for the scorpion’s weaker pincers and lack of brawny strength.
DEATH STALKER SCORPION
Scorpions glow under UV light (black light)

9. Opisthosoma has spinnerets associated with silk glands (there are several types of silk produced)
Silk may also be used by young spiders for dispersal (called ballooning)
Female may attract male with pheromones or male may attract female by plucking on her web
Sperm given to female with pedipalps, female lays up to 3,000 eggs in silk case
Order Opiliones
Harvestmen or daddy longlegs
Prosoma and opisthosoma are joined (making body look oval/ovoid)
Many are omnivores (feed on plants and animals)
Sperm transfer is direct by penis like structure

10. World’s Most Venomous Spiders…
The Brazilian Wandering Spider
(Guinness World Records 2007)

11. Australian Funnel-web Spider

12. Order Acarina Class Pycnogonida
Mites and Ticks (mostly “ectoparasites”)
Prosoma and opisthisoma are fused
Capitulum projects from anterior carrying mouthparts
Chelicerae and pedipalps modified for piercing, biting, anchoring, and sucking.
Do not permanently attach to host (parasite???)
Some carry diseases (Lyme Disease; Rocky Mountian Spotted Fever)
Class Pycnogonida
Sea spiders (marine, located on ocean floor)

13. Mites vs. Ticks Mite Tick
Mite
Tick

15. Subphylum Crustacea Almost all aquatic 2 pairs of antennae
Biramous appendages (appendages separate into 2 parts at distal end- making “Y” shape)
5 classes (3 common)

16. Class Malacostrata Largest class of crustaceans
Includes shrimp, crabs, lobster, crayfish, mysids, krill, isopods, and amphipods
Feed on other invertebrates, plant matter, and dead/decaying animals
Sensory structures = Compound eyes, simple eyes, statocysts, chemoreceptors, proprioceptors, and tactile setae.
Excretory organs (green glands) are at bases of second antennae
Dioecious (most young hatch as mini adults)
Most larvae planktonic (with a single median photoreceptor)

17. Appendages (of most crustaceans):
Pairs 1-2 = Antennae
Pairs 3-5 = Associated with mouth
3 = Mandibles (chewing/grinding)
4-5 = Maxillae (food handling; #4 has a gill)
Pairs 6-8 = Maxillipeds (sensory and food handling)
#7-8 have gills
Pairs 9-13 = Pereopods (mainly for walking; contains gonads)
9 = cheliped (pincher to capture food)
All but last pair after perepods = Pleopods (swimmerets)
Last segment (flipper)= Telson (anus) which has appendages called uropods

18. Class Branchiopoda Class Maxillopoda
Fairy shrimp, brine shrimp, water fleas
resistant embryos are found in this group because they usually live in temporary ponds, salty environment, or need to survive over winter
Class Maxillopoda
2 common groups: copepods and barnacles
Most copepods planktonic with median ocellus and very important to marine food webs
Most barnacles are monoecious
Barnacles attach to a variety of substrates (sometimes by a stalk) and some are modified parasites

19. Subphylum Myriapoda “Myriad” = ten thousand 2 tagmata (head and trunk)
4 classes (2 common)
Class Diplopoda = millipedes
trunk segments
Round in cross section
Food = decaying plant matter
Roll into a ball or release hydrogen cyanide when threatened
2 pairs of legs per segment

20. Class Chilopoda = centipedes
Nocturnal
Flat in cross section
Carnivores (arthropodss, worms, snails, frogs)
Poison claws to kill/immobilize prey
One pair of legs/segment

21. Subphylum Hexapoda “Hexa” = six (3 pairs of legs?)
Mouthparts project from head
Most have wings capable of flight
Most have 1 pair of antennae
3 tagmata: head, thorax, and abdomen
Brain = ganglion (some capable of learning/memory)
Compound eyes (as well as other sensory structures)
Molting with metamorphosis
Tracheal system for gas exchange
Blood is not used for gas transport!
Complex mating behaviors= high reproductive potential
Some insects are social