Transport by Water 



51 



flat planktonic organism, long thonght to be another species entirely, 

 was the larva of the eel. The Danish marine biologist, Johannes 

 Schmidt, then set out to find the spawning ground from which the 

 larvae came. Little did he know, when he began, that his search 

 would require many years of work and thousands of miles of explora- 

 tion before he answered the question. By plotting the occurrence of 

 smaller and smaller larvae, Schmidt ( 1925 ) gradually traced the drift 

 of the larvae back to its point of origin southeast of Bermuda (Fig. 

 2.12). Here the eels spawn apparently deep in the water, since no 



Redrawn from Schmidt, 1925 

 Fig. 2.12. Migrations of the eel. Dotted lines indicate drift of larvae from breed- 

 ing areas of American eel ( A ) and European eel (E). Solid lines indicate return 

 migration of the adult eels. 



one has seen them. The newly hatched larvae drift into the Gulf 

 Stream and after three years are carried to the European shore, 

 where they metamorphose into elvers and enter the rivers. The ma- 

 ture eels make the return trip under their own locomotion, although 

 how they find their way across two or three thousand miles of ocean 

 is a complete mystery. 



