THE LOWER FISHES 



163 



undulating waves of the pectoral for slow locomotion, but flap their "wings" like 

 a bird more than do the skates when they desire to move fast. The eagle and 

 manta rays flap their wings exclusively and are able to move rapidly in this 

 way. Turning in all rays is accomplished mainly or exclusively by the pectoral 

 fins. Some rays, particularly the "flying" ones are among the most graceful of 

 fishes. Thev are also among the most powerful things that swim as anyone 

 who has hooked one can attest. 



As befits their largely bottom-living habits, rays are dark on the upper surface 

 while the lower surface remains white and patternless. The upper surface is 

 sometimes patterned to resemble the substrate over which the animal lives. 



Most rays are rather sluggish and nocturnal and, though powerful swimmers, 

 are not as speedy as sharks or bony fishes. It is expected, therefore, that they 

 would abandon the fish-eating diet of sharks for more easily caught food such 

 as invertebrates. Most of them cannot see their food as they grasp it with their 

 mouths, but must settle over the active food species with their bodies or dig 

 for the less active ones in the bottom. They are the only fishes that are known 

 to settle over and trap food with their bodies, but they do not envelop prey 

 with their wings as has been supposed. Most rays possess many rows of small, 

 sharp, or flattened teeth arranged so as to act in a grasping or crushing manner. 



Rays vary in size from a few inches to 23 feet (across the pectorals) and are 

 found all over the world from arctic to tropical waters. Some sting rays and 

 sawfishes even enter fresh water. Rays allow close approach since they are not 

 timid animals. By day they are often seen asleep on the bottom. They are, 

 therefore, easy prey for the swimmer, but the authors do not consider it either 

 very good sportsmanship nor verv good sense to molest them. It must be remem- 

 bered that even rather small rays are powerful, and many, if not most of them, 

 can be dangerous, as we shall see in the following pages. 



There are fi\'e major groups (superfamilies) of rays. 



Sawfishes: Superfamily Pristoidea 



These are the most sharklike of the rays. The presence of the extended snout 

 bearing saw teeth is an unmistakable and unique identifying character. This 

 saw can be a very formidable weapon. Sawfishes are ovoviviparous. The saw 

 of newly born sawfish is covered by a sheath in order to protect the female. 



