1. Arthropods

2. What are ARTHROPODS? Coelomate – definition? Segmented – definition?
Bilateral Symmetry – definition?
Exoskeleton – made of protein and chitin
Jointed appendages – any structure (leg or antennae) that grows out of the body

3. What are Arthropods?
Earliest invertebrates to exhibit jointed appendages
Jointed appendages are an advantage because they allow more flexibility for animals with hard, rigid exoskeletons
Joints allow powerful movements and allow appendages to be used in many ways

4. What are Arthropods?
Appendages
Jointed Appendages

5. Phylum Arthropoda: crustaceans, spiders, insects
-Hard exoskeleton, segmented bodies, jointed appendages
-Arthropods are the most successful of all animal phyla based on diversity, distribution, and numbers. 
-Nearly one million species identified so far, mostly insects.
-The exoskeleton, or cuticle, is composed of protein and chitin.
-Molting of the cuticle is called ecdysis.
-Extensive cephalization. 
-Open circulatory systems in which a heart pumps hemolymph through short arteries and into open spaces (sinuses).
-Aquatic members- gills for gas exchange; terrestrial members- tracheal system of branched tubes leading from surface throughout body.

6. Exoskeletons Provide Protection
Made up of protein and CHITIN Continuous - covering over most of body OR Plates - that are held together by hinges
Continuous
Hinged

7. Exoskeleton Advantages
Protects, supports internal tissues Provides place for muscle attachment Aquatic arthropods have exoskeleton reinforced with calcium carbonate

8. Exoskeleton Disadvantages
Heavy
the larger the animal, the thicker and heavier the exoskeleton
Exoskeletons don’t grow
animals must molt when they get too large for exoskeleton

9. Molting
Animal contracts muscles and takes in air or water Body swells and causes exoskeleton to split open, usually along the back
Most arthropods will molt 4-7 times before becoming an adult.

10. Before the new exoskeleton hardens...
Increased circulation to all parts of the body cause the animal to puff up and new exoskeleton hardens leaving some “growing room”
Animal can’t protect itself, can’t move
What is another term for molting?
Ecdysis

11. Segmentation
3 segments
Abdomen
Thorax
Head

12. Segmentation Sometimes these segments can be fused together
some have head and fused thorax and abdomen
some have abdomen
and fused head and
thorax (cephalothorax)

13. Respiration Efficient respiratory systems to meet large O2 demands
Large oxygen demand needed to sustain high metabolism for fast movements
3 types of respiratory structures
gills (aquatic arthropods)
tracheal tubes (terrestrial arthropods)
book lungs (terrestrial arthropods)

14. Respiration Gills water moves over gills O2 from water diffuses
into gills and into
bloodstream
CO2 from body diffuses out through gills into surrounding water

15. Respiration Tracheal tubes
branching network of hollow air passages that take air throughout the body
Muscle movement brings air in/out through SPIRACLES (openings in abdomen and thorax)

16. Respiration Book lungs spiders and relatives
air filled chambers with leaf-like plates
stacked plates
are arranged
like pages
of a book