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SUBPHYIUM VERTEBRATA: 



modified gill-like cleft (spiracle) behind each eye; 

 without scales in adults (Figure 16.10). 



The chimaeras, also called ghost fishes or ratfishes, 

 typically are deep-sea fishes; they are known to live at 

 depths of over a mile. Although they also inhabit 

 shallower waters, the Pacific Coast is one of the few 

 places where they occur just below the intertidal level. 

 In this area, chimaeras sometimes are trapped by re- 

 treating tides and may be found in tidepools. 



These are scaleless "fishes" of grotesque appear- 

 ance, hence their common name, chimaera, which 

 originally was applied to a mythological monster. An 

 additional unattractive structure is the heavily spined, 

 club-like, strictly male organ that stems from the 

 "forehead." Although the function of this club is not 

 really known, it is assumed to play a part in court- 

 ship. 



The Holocephali probably are an archaic group, 

 perhaps a group on its way to extinction. This 

 premise is supported by there being nine known fossil 

 families but only three living families in the order. 

 Moreover, the living ratfishes are a very small group 

 among the living fishes. However, as one should 

 know by now, certain taxa of very small size may 

 persist for geologically long periods of time. 



Chimaeras feed upon hard invertebrates, especially 

 shellfish, and their mouths are specialized for this 

 purpose. Both upper and lower teeth are fused into 

 solid plates, and the upper plate is fused to the skull. 

 This arrangement provides a strong vise-like struc- 

 ture that is marvelously suited for its purpose. 



ORDER SELACHII (Sharks and Rays) 



Diagnosis: gills in five to seven separate clefts 

 visible along each side of pharynx; form torpedo-like 

 or flattened; jaws with individual placoid scales modi- 

 fied into teeth; spiracle and scales present in adults 

 (Figure 16.10). 



Suborder BATOIDEA (Rays) 



Diagnosis: gill slits on underside of body; body 

 generally flattened; front (pectoral) fins enlarged, at- 

 tached along each side of head and body. 



The Suborder Batoidea includes animals called 

 skates and rays. In general, skates have longer, 

 thicker tails, and the pectoral fins and front part of 

 the body are not expanded to the point that a circular 



disc is formed. All members of the suborder have 

 somewhat similar habits in that most are shallow- to 

 deep-water bottom feeders on shellfish; mollusks and 

 crustaceans are crushed by the numerous, small, flat- 

 tened teeth. Swimming is accomplished by a rippling 

 action of the "wings" which are broadly expanded 

 pectoral fins, each fin attaching to almost an entire 

 side of the body. Therefore, the primary adaptations 

 are to a bottom existence. 



The sawfish is a ray that is more shark-like in its 

 general appearance. It receives its name from the 

 "saw" (a structure also found in some sharks) pro- 

 jecting from its snout. Moreover, sawfishes possess 

 other shark-like features. Sawfishes use their saws to 

 dismember and kill their prey, mostly fish; they have 

 shark-like swimming structures and swim like sharks. 

 However, true sawfishes have gills under their bodies 

 and still on the pectoral fins. 



The torpedo, or electric, rays have modifications of 

 the "wing" muscles that enable these muscles sud- 

 denly to release electrical energy. When disturbed, 

 these fish can deliver a powerful shock. Fortunately 

 they are found at moderate depths, so only commer- 

 cial fishermen have much contact with them. These 

 fishermen have a healthy respect for electric rays. 



The stingrays are fairly common inshore along the 

 coast. Not uncommonly, stingrays inflict painful, 

 slow-healing wounds on swimmers and people clam- 

 ming in coastal waters. These wounds are inflicted 

 by the "stinger," a spine on the tail. The materials 

 injected by the stinger, whether they be formed by 

 the animal or acquired from its environment, are 

 considered poisonous. Unfortunately, there is no 

 known remedy to counteract the injected poisons. 



The manta or devil rays are very large. The record 

 California specimen, a female, was 18 feet wide and 

 weighed 2310 pounds. In southern waters they are 

 known to reach about 22 feet in width and about 3000 

 pounds in weight. Fortunately they have neither the 

 equipment nor the habits to mistake man for food — 

 these animals use their gill apparatus to filter tiny, 

 free-swimming life. However, one habit tends to 

 cause consternation among humans in small boats. 

 Characteristically, these giants make spectacular 

 leaps out of the water, falling back with crashes like 

 gunshots. 



The skates are the quiet, serene members of this 

 suborder, but they follow the general habits already 

 outlined for the entire group. They are not known to 

 harm man in any direct way. 



