1. Phylum Arthropoda
By Kayla Wilkinson

2. Class Arachnida 30,000 species
Includes spiders, scorpions, mites, and ticks
Spiders are the largest group
2 body regions: cephalothorax and abdomen in most arachnid
6 pairs of jointed appendages

3. Class Arachnida First pair of appendages known as chelicerae
Located near the mouth
Often modified pincers or fangs
Pincers used to hold food and fangs inject prey with poison
Spiders have no mandibles

4. Class Arachnida Second pair of appendages known as pedipalps
Adapted for handling food and for sensing
In male spiders modified for carrying sperm during reproduction
Four other appendages are modified legs used in locomotion
Arachnids have no antennae

5. Class Arachnida Ticks and mites have one body section
Head, thorax, and abdomen are fused
Ticks feed on blood from reptiles, birds, and mammals
Capable of expanding up to 1 cm or more after a meal
Also spread diseases

6. Class Arachnida Mites are so small they are often not seen
You can feel them bite though
Scorpions easily recognized by many abdominal body segments and enlarged pincers
Long tail with venomous stinger at tip
Use it to paralyze large prey
Habitat: warm dry climates
Eat insects and spiders

7. Class Crustacea
Many are aquatic and exchange gases as water flows over feathery gills
Only arthropods to have 2 pairs of antennae for sensing
All have mandibles for crushing food, and 2 compound eyes
Mandibles open and close from side-to-side
Many have 5 pairs of walking legs
First pair often modified into strong claws for defense

8. Class Crustacea
Include crabs, lobsters, shrimps, crayfishes, barnacles, water fleas, and pill bugs
Some have 3 body sections and others have 2
Sow bugs and pill bugs are only land crustaceans
Found in moist habitats

9. Class Chilopoda Centipedes Many tiny jointed legs Flatten bodies
Carnivorous, eat soil arthropods, snails, slugs, and worms
When bitten it’s painful to humans
Have Malpighian tubules for excretion
Tracheal tubes for gas exchange

10. Class Diplopoda Millipedes
Eats mostly plants and dead material on damp forest floor
Do not bite but can spray obnoxious-smelling fluids from their defensive stink glands
Cylindrical body
Move slowly and graceful
Tracheal tubes for gas exchange
Malpighian tubules for excreting waste

11. Class Merostomata Horseshoe crabs Considered living fossils
Remained relatively unchanged since Cambrian period
Heavily protected by extensive exoskeleton
Live on sandy or muddy ocean bottoms for seaweed, worms, and mollusks

12. Class Merostomata They migrate to shallow water during mating season
Females lay their eggs on land, buried in sand above the high water mark
Newly hatched horseshoe crabs look like trilobites

13. Class Insecta
Includes flies, grasshoppers, lice, butterflies, bees, beetles, and more
Largest group of arthropods
Insects mate once or only a few times during their lifetime
Eggs are fertilized internally. Some species shells form around them
Most lay large amounts of eggs

14. Class Insecta
Undergo metamorphosis which is a series of changes controlled by chemical substances in the animal
Complete metamorphosis has four stages: egg, larva, pupa, adult
Incomplete metamorphosis has three stages: egg, nymph, adult