THE LOWER FISHES 135 



The prey is usually dead or dying fishes though it is possible that healthy 

 fishes may sometimes be taken. Thus, they may be considered a sort of cross 

 between a parasite and a scavenger. They bore into the prey, usually at the neck 

 with the tongue, or they may even enter the body through the mouth. Once 

 inside, the prey is eaten from inside out and only a sack of skin is left. Great 

 losses to fishermen have occurred when hagfishes have entered the bodies of 

 fish caught in sill nets or on set lines. Over a hundred hagfishes have been 

 retriexed from the bodv of a single fish. They seem to locate prey by smell 

 rather than by sight as do lampreys. They are mainly nocturnal and lie buried 

 in the mud most of the time. 



Hagfishes are sometimes caught on lines themselves. They swallow a hook 

 deeply, even as far as the anus. 



These fishes do not enter fresh water to breed. Small numbers of large, shelled, 

 adhesive eggs are laid in the sea where they sink and stick to the first object 

 they touch. 



The name "slime eel" is derived from the fact that they can exude huge, 

 dripping quantities of mucus from the skin when caught. A large one can fill 

 a two gallon bucket with slime exuded from the mucus glands on the sides. 



Their distribution is world-wide in temperate seas, and they seem to prefer 

 cool water. 



PACIFIC hagfish: Bdellostoma stouti 



Size: Up to 2 feet. 



Distrihution: From southeastern Alaska to southern California. 



Identification: Same as for the family. 



Habits: This hagfish is especially abundant around Monterey Bay at depths 

 of 10 to 20 fathoms. It preys chiefly on disabled or netted rockfish, Sehastodes, 

 and various flounder. About twenty large eggs are deposited on rock or shell 

 bottom in early summer, but breeding may occur at any time of year. These 

 eggs are oblong and connected together by hooks at their ends. 



Similar Species: The slime eel (hagfish), Myxine glutinosa, is the Atlantic 

 form, found from the arctic south to Cape Hatteras. It keeps to deeper waters 

 at the southern end of its range and reaches 18 inches in length. 



THE SHARKS AND RAYS: Class Chondrichthyes {"cartilage 

 fish"), Subclass Elasmobranchi {"plated gills") 



This subclass omits the strange ratfishes which will be discussed later. It is a 

 very ancient group which has been in existence for over 300 million years. 

 With all that time available for their evolution, it would be expected that sharks 

 and rays would be very diverse in body form and habits, but thev are not. 

 Evidently their body plan has been a successful one, and it has not been varied 

 nearly as much as the bony fishes for instance. There are but two basic body 

 plans, a cylindrical one as seen in sharks and a flattened one as seen in rays. 



This group is a mysterious one. The underwater swimmer should avail 

 himself of every opportunity to observe its species since the habits of very few 

 are well known. For this reason, the groups will be considered here in some 

 detail. Furthermore, because of the great amount of talk, based on little knowl- 



