THE ELEVEN BRANCHES OF THE INVERTEBRATES 401 



20. Colors. — Give examples of alluring, warning, and terrifying colors; 

 also of protective resemblance. 



21. Tools, weapons, or other means of offense or defense? 



22. Does Campodea show worm-Uke ancestry? If so, what is the line of 

 descent of insects? 



23. From Campodea, or some other primitive form, how would you 

 account for the orders of insects by descent with modification? 



24. Wheeler (in "Ants") attributes the dominance of ants to their (1) 

 universal variabiUty; (2) wide distribution; (3) numerical ascendancy; (4) 

 longevity; (5) abandonment of detrimental specialization; and (6) versa- 

 tility of their relations with plants and other animals. 



Compare other animals on these six points as to their dominance. What 

 are your conclusions? 



25. Dominance. — Is success the criterion of superiority in animals and 

 plants? If so, what are the superior classes of Arthropodaf The dominant 

 or superior order of Crustacea? of Arachnida? of Myriapodaf Of insects, 

 the dominant species of Arthropodaf 



26. Preparedness. — What arthropods are best prepared (and in what 

 ways do you mean?) to maintain the struggle for existence? - 



27. Compare the complexity of body structure and mind manifestations 

 of Arthropoda with that of worms in general. See 16 under Worms for 

 body systems and animal behavior. Laboratory Guide, pp. 12-14. 



THE ELEVEN BRANCHES OF THE INVERTEBRATES 



1. W^hat have they in common in structure that makes them rank as 

 invertebrates? 



2. How does the branch Chordata differ in structure from the inver- 

 tebrates? See Chordata, p. 189. 



3. Give three general characteristics of each branch of the invertebrates, 

 as to their body- and appendage-segmentation, body symmetry, body- 

 structure as to body or germ layers (ectoderm, mesoderm, and endoderm). 



4. Symmetry. — What branches afford examples of radial symmetry? 

 of bilateral symmetry? of asymmetric symmetry? of more than one kind 

 of symmetry? Influence of symmetry on the locomotion of animals? 



5. Habitat. — What branches show aquatic forms? aerial forms? ar- 

 boreal? terrestrial? subterranean? What branches show more than one 

 habitat? Any exclusively marine forms? fresh-water forms? 



6. Food. — What branches have carnivorous forms? herbivorous ones? 

 omnivorous ones? 



7. Locomotion. — Name and trace all means and modes of invertebrate 

 locomotion. Do any branches have a common kind of locomotion? If .so, 

 what ones? 



26 



