[Annals N. Y. Acad. Sci., Vol XXII, pp. 321-326, 5 December, 1912] 



CHANGES IN THE BEHAVIOK OF THE EEL DURING 

 TRANSFORMATION 



By Bashfokd Dean 



{Bead in abstract before the Academy 13 May, 1912) 



The literature of animal behavior gives as yet little attention to the 

 changes which occur in animals during the period of metamorphosis. 

 This is a gap in our knowledge not remarkable perhaps when we con- 

 sider how little is yet recorded of the behavior of many types of adult 

 animals, even of common forms. None the less, it is precisely during 

 the period of transformation that one may expect to find clues as to 

 interesting conditions in mind-mechanism, for during this short period 

 adjustments are completed which change, as it were, one functional 

 "species" into another ; for an animal may remain for years in its larval 

 form almost unaltered, and it may subside again into a changeless form 

 after a kaleidoscopic transformation. In fact, the more sudden the 

 change in transformation, the more interesting it should be from the 

 point of view of connecting habits with structures, for it would here 

 bring into sharpest relief morphological changes and make them the 

 more easily linked with changes in behavior. 



In the larval history of fishes, observations in this field have rarely 

 been recorded. The teleosts, where conspicuous larval stages occur, are 

 little studied, even in the case of those members of the group which have 

 the most complete metamorphosis. 



The form-changes of eels have been described by a number of authors 

 (Grassi, Calandruccio, Cunningham, Eigenmann and others), and the 

 changes are so marked that we can readily predict from them striking 

 changes in behavior. That the latter actually occur, and in marked 

 degree, was clearly brought home to the writer when an opportunity 

 came to him in Japan (Misaki) to observe the transformation of a 

 Leptocephalus into a Conger, — possibly Conger (Leptocephalus) mala- 

 baricus (Day). 1 His notes, especially upon its behavior, are perhaps 

 worthy to be recorded on account of the interesting nature of the "larva" 

 and from the fact that this form is not apt to be observed. In point of 

 fact Leptocephalus seems rarely to have been kept living in an aquarium 



i Francis Day : "The Fishes of Malabar." PI. xix. 1865. 



(321) 



