Name ___________________________

Understanding Evolution - The Arthropod Story
http://evolution.berkeley.edu/evolibrary/ --- Go to Examples of Evolution
-- then to Interactive investigation: The arthropod story

1. List the five main groups of arthropods.

2. Sheer Numbers …
a) How many insects exist for every human? ________
b) If all the ants on the earth formed a chain, how many times could the earth be circled? ____
c) What are the most abundant animals in the ocean? _____________________
3. Habitat and Distribution
a) What arthropod lives more than a mile below the ocean? _________________________
b) What is the largest centipede species? ______________________________
c) What arthropod lives at high altitudes? ________________________________
d) What arthropod can withstand heats of over 140 º? ______________________________
4. Ecological Niches
a) What type of arthropod is a farmer? ___________________________________
b) Where does the parasitic arthropod Cymothoa exigua live? _______________________
c) What type of arthropod cleans fish scales of parasites? ___________________________

5. What are the five branches of the arthropod tree?

6. List the five characteristic of arthropods.

7. a) Describe bilateral symmetry. _____________________________________________

b) Check those that are bilaterally symmetrical. ___ millipede ____jellyfish _____scorpion

8. a) Segments are grouped into larger sets, such as the abdomen and the _______________
b) Check those that are segmented. ___onychophoran ____ mouse ___jellyfish ____moth

9. a) What substance is the exoskeleton made from? ________________________________
b) Check those with an exoskeleton ____ mouse _____moth _____ jellyfish _____millipede

10. a) Side Trip: Support Systems. Name the three types of support systems found in the animal kingdom. _________________________________________________________
b) Which one is possessed by humans? __________________________________
c) What kind of skeleton does an earthworm have? __________________________

11. a) What does the word "arthropod" mean? ____________________________________
b) Check those that have jointed appendages.
millipede ___ moth ____ onychophoran ___ mouse ____ jellyfish

12. a) Name five ways in which limbs can be specialized.

b) Which have many pairs of limbs? ____ mouse ___ moth ____ millipede_____scorpion

13. Based on these data, check all of the following animals that are arthropods.

scorpion
moth
onychophoran mouse
millipede
jelly

14. A Closer Look at the Arthropod Branches
a) How many body parts do insects have? _______ How many pairs of legs _______

b) How many body parts do chelicerates have? _________ How many pairs of legs ___________
Do chelicerates have antenna? __________

c) Do crustaceans have antenna? _________ Give two examples of crustaceans. _________________

d) Give two examples of myriapods: ___________________________________________
e) Name the 3 lobes of the trilobite body: ________________________________________

15. a) How long ago was the Cambrian period?____________________
b) What is the "Cambrian Explosion" _____________________________________________

16. Sanctacaris
a) Nickname __________________________
b) Is it part of the arthropod lineage? ________________________
c) Sanctacaris added as a branch to what part of the tree ___________________________

17. Opabinia
a) How did it acquire food? _________________________
b) Is it part of the arthropod lineage? ________________________
c) Opabinia lacks what namesake trait of arthropods? _____________________________

18. Pikaia
a) Is it part of the arthropod lineage? ________________________
b) Pikaia was probably what type of animal? __________________________

19. Hallucigenia
a) Is it part of the arthropod lineage? ________________________
b) Hallucigenia added as a branch to what part of the tree ___________________________

20. Naraoia
a) Is it part of the arthropod lineage? ________________________
b Naraoia added as a branch to what part of the tree ___________________________

21. a) How long did trilobites lives? _________________________________
b) When did the mass extinction occur that killed the trilobites? ____________________________
22. a) How is a trilobite like a pill bug? ______________________________
b) What were the spines on the trilobite used for? __________________________________

23. Crustaceans: Living Toolboxes. For each tool, describe how the appendage of an arthropod is similar.
Crowbar _________________________________________________
Paddle __________________________________________________
Broom ___________________________________________________
Leaf blower _______________________________________________
Clamp ___________________________________________________
Sledgehammer ____________________________________________

24. Sidetrip: Little Mutations with Big Effects. What is a HOX gene? What can happen if this gene is mutated?

25. Describe two ways the legs of arthropods are adapted for different purposes.

26. Sidetrip: Extreme adaptations: Eating with your feet. Sketch the head of an insect and label the mouthparts

27. a) What is an evolutionary constraint?_____________________________________________
b) What are three constraints on arthropods? ____________________________________________
28. Why does molting limit an arthropod's size? ____________________________________________
29. How does strength limit the arthropod's size? ____________________________________________
30. a) How do insects get oxygen? ______________________________________________________
b) How does this limit their size? _____________________________________________________