1. Phylum Arthropoda Textbook pgs. 335-342
Spiny-backed orb weaver

2. Arthropod Classes Crustaceans Insects Centipedes Millipedes Arachnids
Trilobites (extinct)

3. Body Characteristics Body Symmetry: Bilateral symmetry
Cell Organization: Cells to tissues to organs to organ systems
Reproduction: Sexual
Body development: Most arthropods go through METAMORPHOSIS

4. Just the facts… Fully developed to life on land
No need of a moist environment
Only invertebrates to fly.
Live in salt and fresh water, soil, land, air
Size ranges from tiny mites to over 3 feet.
Largest phylum in the animal kingdom.

5. Characteristics of Arthropods
Invertebrate
External skeleton-Exoskeleton
Segmented body
Jointed attachments called appendages
Wings, mouthparts, antennae, legs
Open circulatory system
Internal fertilization
most reproduce sexually
They are EITHER male or female

6. An Arthropod Exoskeleton
Waterproof shell
Used for protection
Helps prevent evaporation, keeps them from drying out
Place for muscle attachment
Made out of chitin
As the arthropod grows larger, it can’t expand, so it must shed its exoskeleton
Process called molting
Pillbug molting its exoskeleton

7. Molting
The difference between a soft-shelled crab and a hard-shelled crab
A horse-shoe crab.
Adult cockroach

8. CRUSTACEANS CEPHLATHORAX and ABDOMEN GILLS FOR BREATHING
Fiddler Crab
CEPHLATHORAX and ABDOMEN
(2 BODY PARTS)
GILLS FOR BREATHING
HARD OUTER SHELL

9. Crustacean Body Segments
Head and thorax combined
Cephlathorax
Then an abdomen

10. ARACHNIDS Head and Abdomen Breathe with organs called book lungs
Four pairs of legs
Breathe with organs called book lungs
SOME BUT NOT ALL BUILD WEBS

11. Scorpion
Tarantula
Black Widow
Tick

12. CENTIPEDES 2 body sections 100 LEGGER ONE PAIR OF LEGS PER SEGMENT
Head with antennae
Long segmented abdomen
100 LEGGER
ONE PAIR OF LEGS PER SEGMENT
LONG, FLAT BODIES
CARNIVORES

13. MILLIPEDES 2 body sections Head with antennae
Abdomen with at least 80 segments
“1000 Legger”
Most of the body segments bear two pairs of legs.
Rounder bodies
Feed on decaying vegetable matter and are herbivores
Will curl up to avoid predators.

14. Insects The Importance of Insects: Pollination of flowers
Destroy harmful pests
Make silk fibers
Larva of the silkworm moth
Make food products
Bees make honey

15. Insect Impact on Humans
Damage to major crops
Can carry diseases
Ex. – some mosquito species cause malaria
Mosquito on Human Skin

16. Why Insects are So Successful
Reproduce very quickly (short generation time)
Females produce many young
Ability to eat a variety of foods

17. Why Insects are So Successful
Different species have become adapted to live in almost ANY environment
Ability to fly (can travel for food and mates)
Mosquito in Flight

18. Insect Body Structure Insects have: Three body parts
HEAD, THORAX, ABDOMEN
3 pairs of legs attached to the thorax
1 pair of antennae attached to the head

19. Insect Body Structure Simple and compound eyes
Most insects have one or two pairs of wings attached at the thorax
Many have tubes (spiracles) which allow oxygen to travel directly to the insect’s body cells

20. Insect Metamorphosis
Gradual Metamorphosis: the egg hatches into a young insect that looks like the adult, only smaller
Ex. Grasshoppers, termites cockroaches and dragonflies
3 stages –
1.The egg
2. hatches into a nymph
3. the nymph molts several times growing into a larger nymph
4. eventually becoming the adult.

21. Insect Metamorphosis cont’d
Complete Metamorphosis: the young insect looks very different from the adult form
Ex. Butterflies, beetles, houseflies, and ants
4 stages –
The egg hatches into a
larva,
the larva forms pupa, and
the pupa turns into an adult.

22. Insect Examples Black Blister Beetle Thistle Caterpillar
17-year Cicada

23. Robber Fly Catching a Bee for Dinner
Insect Examples
Moss Mantid
Weaver Ants
Robber Fly Catching a Bee for Dinner
Tropical Cockroach

25. TRILOBITES
ONCE THE LARGEST GROUP OF ARTHROPODS
EXTINCT.

26. Comparison of the largest Arthropod Groups
Characteristic
Crustaceans
Arachnids
Insects
# of Body Sections
2 or 3 2 3
# of legs
5 or more pairs
4 pairs
3 pairs
# of antennae
2 pairs
1 pair
Where found
Water or damp places
Mostly on land
Example
Lobster
Tarantula
Praying mantis

27. Arthropod Review