1. Arthropods Chapter 28

2. Arthropods include: Insects, Arachnids, Crustaceans, Centipedes

3. Common characteristics of all arthropods: 1.Invertebrates-no backbone 2.Bilateral symmetry- divide into 2 equal sides at one point 3.Coelom- cavity around internal organs 4.Exoskeleton-outside body skeleton 5.Jointed appendages- structures growing out of body have joints 6.Open circulatory system – blood pools in spaces (not vessels)

4. Common characteristics cont… 7. Complete digestive system -mouth, intestines, stomach, anus 8. Mandibles-a variety of jaws/ Functions: hold, chew, suck, and bite

5. Appendages Used for 1. locomotion, 2. sensing, 3. feeding, 4. mating

6. Exoskeleton Hard thick covering made of protein & chitin May be solid all over body or may be in segments Functions 1. Protect 2. Support internal tissues 3. A place of attachment for muscles, prevents 4. Water loss

7. Exoskeleton growth Can’t grow as the body grows They must shed the old skeleton & grow a new one/process called molting The new skeleton will grow underneath & eventually pop off the old one Most arthropods molt 4-7 times in life

8. Most arthropods have 3 segments to their body These include: -The head -The thorax (chest area) -The abdomen

9. How do arthropods breathe (respire)? 1. Aquatic arthropods-use gills ex. Crayfish

10. Breathing cont… 2. Most insects use tracheal tubes -branching networks of hollow air passages that carry air through body. -Muscles pump air through the tubes to openings called spiracles. Ex. grasshopper

11. Breathing cont… 3. Arachnids use book lungs -these air chambers are stacked like books Ex. Spider

12. Arthropods have acute (very good) senses 1.Quick movement Ex. Fly 2.Antennae-use to detect and communicate 3.Pheromones-chemicals used to signal Ex. Ants 4.Acute vision (simple and compound eyes) - detect motion very well -can see in almost all directions except directly behind. Ex. This is why it is hard to hit a fly!

14. Reproduction in Arthropods Most have 1 type of sex organ on each (male or female) A few are hermaphrodites (male & female organs) Types of fertilization -If it lives on land-fertilization is internal -If it lives in water-fertilization is external in water

15. Arthropod classification: Kingdom: Animalia Phylum: Arthropoda Classes: 4 classes

16. 4 classes of arthropods 1.Arachnids-spiders, scorpions, mites, ticks 2.Crustaceans-all are aquatic-lobster, shrimp, crayfish

19. 3. Centipedes & millipedes- they differ on the number of legs on each section & the type of food they eat

20. Class Insecta: Includes millions of species (largest group) Mate only around 1 time in lifetime Eggs are fertilized internally and shells form around the eggs Female lays the eggs after they are fertilized The # of eggs laid is enormous –Purpose: to increase chance of survival

21. Insect cartoon

24. Changes insects undergo after hatching: Metamorphosis-series of changes controlled by chemical substances

25. 2 Types of Metamorphosis: 1.Complete metamorphosis- has 4 stages (ex. Butterfly) 4 stages: a. Egg b. larva-free living worm-like stage (caterpillar) c. pupa-larva tissue broken down and replaced in a case-cocoon d. adult

26. Complete metamorphosis:

27. 2. Incomplete metamorphosis - has 3 stages (Ex. Grasshopper) 3 stages: a. egg b. nymph-smaller version of adult (looks like adult but lacks appendages like wings and cannot reproduce c. adult

28. Know Insect Structures! P. 752 Draw and label the grasshopper Write the functions under each labeled part Leave in notebook to study for test Study drawing, functions and notes for test