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Shark and Company 



THE CHIMAERAS 



The Selachians have a sort of natural "appendix"— a group of very 

 strange animals known as the Chimaeras, a name derived from the old 

 Greek work Khimaros meaning a goat, the female form of which was 

 Khimaira (Kim-eye-ra). Primitive Greek mythology sported a bogey 

 said to have a lion's head, a goat's body, and a serpent's tail, to which 

 the name Khimairon was given, and this word in time came to be ap- 

 plied to any creature that seemed to be made up of parts of different 

 known animals. Thus, it was readily applied to these fish by mariners. 



The Chimaeroids {Ky-meer'oids) seem to form a bridge between 

 the Selachians and the Teleosts, but there is strong evidence that, while 



A Long-nosed chimaera (Harriotta raleighana). 



Courtesy, The Sears Foundation for Marine Research from 

 Fishes of the Western North Atlantic by Henry B. Bigelow and WiUiam C. Schroeder, 1953 



they are descended from the former, they are not the ancestors of the 

 latter. These strange fish, called Ghost sharks, Spookfish, Ratfish, or 

 Chimaeras, have the cartilaginous skeleton and claspers of Selachians, 

 and the covered gill openings— the familiar gills— of Teleosts. The males 

 also have a third clasper on their foreheads. This bizarre structure, 

 unique among known fishes, is believed to be used in some way in 

 mating, but its definite use is still an ichthyological mystery. All the 

 Chimaeroids are oviparous, laying large (some are I6V2 inches long) 

 egg cases, some of which are tadpole-shaped. 



According to most authorities, Chimaeras are not, as they seem to be, 

 links between Selachians and Teleosts. The theory of their place in the 

 phylogenetic spectrum is best stated by Bashford Dean, who made a 

 long study of this odd breed. In 1908 he wrote: 



From an examination of their fossils, anatomy and embryology, the conclu- 

 sion is reached that they are to be classed not as ancestral sharks, but rather as 

 a group highly divergent from some early shark stem. The few undeniably 

 primitive features which they possess are heirlooms from some Palaeozoic 

 Selachian ancestor— features which modern sharks have not as well conserved. 



