180 SEGMENTED WORMS— THE ANNELIDS 



death has resulted from such loss of blood when a person has been in- 

 jured and unable to keep these leeches off his body. A few of these are 

 found in the Everglades of south Florida. In North Africa, Asia Minor, 

 and China there is a variety of leech known as the horse leech, so called 

 because it often attacks the pharynx and nasal passages of horses. The 

 leeches enter the nose or throat of the horses when the horses drink from 

 pools and streams where the leeches live. Man may also get them by 

 drinking this water. If he swims in the infested streams, the leeches 

 sometimes enter the urinary passages where they may hang on for 

 months. 



Classification and Derivation of Scientific Words 



Phylum Annelida (L. anellus, a little ring; the body of these worms seems 

 to be made of a number of little rings joined together). 

 Genus A. Lumbricus (L. lumbricus, earthworm). 



species 1. terrestris (L. terrestris, the earth; refers to the habitat of 

 the earthworms). 

 Genus B. Neanthes (Gr. neanikos, youthful). 

 Genus C. Hirudo (L. h'xrudo, leech). 



species 1. medicinalis (were once used by doctors to draw blood 

 from patients ) . 



REVIEW QUESTIONS 



1. What activities of the earthworm make it economically valuable? 



2. What is the function of the pharynx, crop, gizzard, and typhlosole in the 

 earthworm ? 



3. Where is the hemoglobin found in the earthworm's blood? How does this 

 compare with the blood of vertebrates ? 



4. Explain excretion in the earthworm. 



5. How can an earthworm move either backward or forward by the same body 

 movements ? 



6. Trace a nerve impulse from a sense organ to a muscle. 



7. Compare the functions of the seminal vesicles and the seminal receptacles. 



8. Explain the meaning of the term "hermaphroditic." 



9. Discuss the extent of regeneration in the earthworm. 



10. How is Neanthes conspicuously different from the earthworm in morphology ? 



11. What is meant by the terms ectoparasite and endoparasite ? 



12. Explain the method of copulation in the earthworms. 



13. How does an hermaphroditic animal benefit from cross-fertilization? 



14. Describe the method of cocoon formation and egg laying in the earthworm. 



15. How have leeches been used in medicine? 



16. Compare the method of reproduction in Neanthes with that found in the 

 earthworm. 



17. What systems of organs are present in the earthworm that were not found 

 in ascaris ? 



18. In which direction does the blood flow in the dorsal and ventral blood vessels 

 of the earthworm ? 



