Fishes of the Western North Atlantic 509 



Developmental Stages. Beyond the fact that Mania is ovoviviparous, we only know 

 that embryos which have reached a width of two feet or more resemble their parents 

 closely and that a single embryo has been reported in each of the cases on record. 

 In some cases gravid females have expelled their young prematurely on being har- 

 pooned. 



Habits. It is only while they are swimming at the surface or basking there that 

 Mantas are ordinarily encountered. We suspect that they spend much of their time 

 resting quietly on bottom, otherwise they would be seen more regularly. When at the 

 surface they often curl the tip of one pectoral or of both above water.'^^ One, observed 

 in an aquarium, was seen to use the cephalic fins as an aid in steering, turning them 

 appropriately when making a sharp turn.'^^ Sometimes they somersault, first lifting the 

 head and part of the body out of the water, then revolving edgewise so that one pectoral 

 emerges while the other sinks. At times they leap partly or wholly clear of the water and 

 fall back with a resounding splash that is audible for a long distance in calm weather. 

 We have often heard as many as three to five of them so engaged in an afternoon in the 

 shallows between Cape Sable and Marco on the southwest coast of Florida. ^^^ They 

 swim slowly, often in pairs, sometimes in companies, and they are so unwary that it is 

 easy to approach one closely in a small boat. But they dart ahead at high speed when 

 harpooned or otherwise disturbed. Large ones are so strong and so enduring, if they 

 are not seriously injured, that accounts of their towing a skiiT for hours have appeared 

 repeatedly.i'^^ 



The only firsthand statement of their stomach contents with which we are ac- 

 quainted is that the South Carolina specimens contained "fragments resembling the 

 shells of shrimps," one with a small crab. One was seen to gulp a school of small mullets 

 into its capacious mouth. "^ Presumably they obtain their food, like the Lesser Devil 

 Ray, by swimming open-mouthed through whatever schools of small fishes or plank- 

 tonic Crustacea they may meet. Charges that they damage beds of bottom-living mol- 

 lusks in the Gulf of Mexico or elsewhere have resulted from confusing them with the 

 Eagle Rays. The primary function of the cephalic fins Is to direct the planktonic food 

 to the mouth, for they have been described as moving these fins rapidly in front of the 

 mouth as they swim. Also, It seems that the cephalic fins automatically close on any- 

 thing that may touch the front of the head between them, and there are several records 

 of a Manta becoming entangled in this way with the anchor line of a boat. For example, 

 one taken In the Gult of California held fast to the bow of the small boat from which 



seeing a school of young Mantas only about two feet wide in Florida, but their small size suggests that they may 

 have been the Lesser Devil Ray, Mobula kypostoma. 



152. Norman and Fraser, Giant Fishes, 1937: 82. 



153. Breder, Bull. Amer. Mus. nat. Hist., 9^ (2), 1949: 89. 



154. According to Coles (Bull. Amer. Mus. nat. Hist., 32, 1916: 649), they never wholly clear the water. But Elliot 

 (Carolina Sports, 1846: 85) reported seeing eleven leap "entirely out of the water" on one occasion near Beaufort, 

 South Carolina. Many accounts have appeared subsequently of their doing so. 



155. The 22-foot specimen referred to on p. 508 towed a 25-foot motor boat for more than ten miles, part of the time 

 against the added resistance of an anchor dragging on bottom, and after five hours' resistance it was still alive, 

 with four harpoons and several rifle bullets in its body (La Gorce, Nat. geogr. Mag., 35, 1919: 483). 



156. Elliott, Carolina Sports, 1846: 84, 85. 



