1. The Arthropods
Chapter 16

2. Phylum Arthropoda

3. Phylum Arthropoda Largest phylum in Kingdom Animalia
Anthropoda means “jointed feet”
Includes lobsters, spiders, scorpions, millipedes, and insects
Can be harmful or helpful
Harmful: destroy crops, eat other animals’ food, spread diseases
Helpful: studied by engineers; control the numbers of harmful arthropods; help plants reproduce; make wax, honey, medicine, and silk

4. Phylum Arthropoda All arthropods have:
Exoskeleton – their bones are outside of their body
Chitin – allows the bones to be tough and flexible – they bend without breaking
Arthropods molt – as they grow, their exoskeleton becomes too small – they outgrow the exoskeleton and throw it away
Jointed appendages – their legs and feet have joints (bend)
Body segmentation – most have 3 parts to their bodies
Head
Thorax (chest)
Abdomen (belly)
Open Circulatory System – they have a heart, but the blood goes into the body parts after leaving the heart (not veins)
Ventral Nervous System – Ganglia (nerves) are located near the legs and connected to the brain by one cord

5. Nervous System Anatomy

6. Nervous System Anatomy
Brain – located in the head
Ganglia – nerves in the legs
Ventral Nerve Cord – big nerve that connects the brain and the ganglia
Antennae – come out of the head and do taste, smell, and touch
Compound eyes – insects and crustaceans have these – able to see all around, not just a few directions
______ OR_________
Simple eyes – able to see very little, usually just light and dark

7. Subphylum Crustacea

8. Subphylum Crustacea Lobsters, crabs, crayfish, shrimp
Kingdom Animalia, Subkingdom Invertebrates, Phylum Anthropoda, Subphylum Crustacea
Usually live in the water
Carapace – the back plate of a lobster (the front has 6 plates)
Scavengers: they eat anything! They grind their food into powder using the gastric mill.
They can regenerate (grow new parts)
Reproduce sexually – male gives sperm to the female in the fall, female lays eggs in the spring that hatch in the summer

9. Subphylum Chelicerata

10. Subphylum Chelicerata
3 classes: Arachnida is the most important class
Arachnids have:
8 legs – 2 of these are pedipalps (legs used for sensing and mating instead of walking)
2 major segments
Cephalothorax (head-chest)
abdomen
No antennae or mandibles (jaws)
Have chelicerae instead (mouth that looks like fangs)
Respiration by book lungs
Breathe through their stomachs
Usually 4 pair of simple eyes (8 eyes)
Reproduce sexually – females are usually larger than males

11. Other Arachnids
Scorpions, mites, and ticks

12. Class Insecta

13. Class Insecta 80% of all animals are insects (bugs)
There are 31 orders under Class Insecta
Structure of Insects:
Three pairs of legs (six legs)
Usually have wings
3 segments to the body
Head
Thorax (chest)
Abdomen
One pair of sensory antennae (2 of them)

14. Wings of Insects M0st insects have 2 pairs (4) wings Kinds of wings:
Membranous wings: thin, transparent (see through) – most common kind of wing - like a dragonfly or a bee
Scale-covered wings: butterflies and moths

15. Wings of Insects Continued:
Leatherlike wings: extra set of wings that protects the wings used to fly – like a cover for wings – grasshoppers have these
Horny wings: ladybug wings – thick, protect the smaller wings, cover the back of the bug

16. Digestion (eating) of Insects
Mouth:
Upper lip - labrum
Mandibles - used for chewing
Maxillae – put food into the mouth
Lower lip – labium
Stomach:
Foregut – behind the mouth – this is where salivary glands get the food wet with spit before going to the gizzard to be ground up into powder
Midgut – where the stomach is – gastric ceca put more digestive juices onto the food
Hindgut – place right before the food is excreted (pooped)

17. Respiration, Circulation, Excretion and Reproduction
Respiration: insects breathe in their abdomens through tubes called spiracles
Circulation: the insects heart pumps blood into the abdomen, where it covers the organs – no veins
Excretion: Malpighian tubules are straws that pull nitrogen out of the insect and put it into the intestines, where it will become poop
Reproduction: Sexual reproduction
The male puts sperm in the female
The female then lays eggs that will hatch later

18. Metamorphosis in Insects
Metamorphosis means changing from a baby to an adult
There are two kinds of metamorphosis:
Incomplete metamorphosis (3 stages)
Grasshoppers, cicadas, and true bugs
Egg
Nymph (teenager – looks like a small adult) – only for insects that stay on land (cicadas) OR
Naiad – teenager that doesn’t look like the adult and lives in the water (grasshoppers)
Adult – the bug

19. Incomplete Metamorphosis

20. Metamorphosis Complete metamorphosis (4 stages)
Most insects – butterflies, flies, beetles, mosquitoes
Eggs
Larva – like a little worm (maggots, grubs, wigglers, caterpillars) – childhood bug
Pupa – teenager insect – usually inside a case called a cocoon
Adult – the bug

21. Complete Metamorphosis