Fishes of the JVestern North Atlantic 143 



The embryonic Skate is more shark-like than batoid in its general appearance 

 during the early stages of development; it is slender, with its pectorals and pelvics 

 still represented only by a pair of short rounded lobes on either side and with one or 

 two anal fin-folds besides the dorsals. The external branchial filaments, developed on 

 the second to sixth gill arches, are a prominent feature of its general aspect at this 

 stage, and the tip of its tail is drawn out as an attenuated filament, longer or shorter. 

 The enormous development of the pectorals that finally leads to the "Skate" form com- 

 mences while the external branchial filaments are still persistent and continues until 

 after they have disappeared. The fusion of the pectorals with the sides of the head is 

 normally completed some time prior to birth; however, abnormal specimens are some- 

 times encountered in which the anterior part of one pectoral or the other, or both, 

 continues separate from the head after birth and probably throughout life, as described 

 elsewhere (p. 261). The yolk is entirely drawn within the abdomen some little time 

 previous to hatching, and the abdomens of late embryos are commonly much swollen 

 with it. Newly hatched Skates resemble their parents in general shape, except as noted 

 (p. 140), and they hold as strictly to the bottom as the older ones. 



Habits and Food. Typically, Skates are ground fish, often lying partially buried. 

 When alarmed, a Skate will usually press down against the bottom instead of dashing 

 away, and the colors of their backs blend so closely with the background that they are 

 as difficult to detect as any member of the flounder tribe. But they often rise some 

 distance above the bottom in pursuit of prey, and occasionally a Skate may be seen 

 at the surface, seemingly basking in the sun. 



They are most plentiful on smooth, sandy, gravelly bottoms, or on mixtures of 

 sand and broken shells; they are found much less frequently on soft mud (see also p. 262). 

 To find a Skate among rocks or on ledges is an unusual event, though we have occas- 

 ionally seen them there. 



Observations of Skates in aquaria*" show that they are mostly inactive by day, 

 lying quietly on bottom, often so much buried in sand up to the eyes, spiracles, and 

 ridge of the back that their outlines are not to be seen. But they swim actively by day 

 if disturbed, and after swimming they return to the bottom either by swimming or simply 

 by sinking. To bury themselves they stir the sand by movements of their pectorals, thus 

 allowing it to fall back upon them. 



They advance by gently undulating the margins of the wing-like pectorals as 

 described previously (p. 8); the tail, if used at all, serves only as a rudder and often 

 drags on bottom, leaving a trail behind it. They swim rather slowly unless violently 

 disturbed, when they can advance with astonishing speed. 



Skates are strictly carnivorous and feed mostly at night. The diet for such species 

 as have been studied consists chiefly of crabs and shrimps, lobsters, smaller Crustacea 

 such as amphipods, isopods, mysids, and various polychaete worms. They also eat 



fertilization, duration of incubation, and other aspects of the early life history of several of the more common British 

 Skates. 

 40. Schmitlein, Mitt. Zool. Stat. Neapel., j, 1878: 9. 



