574 ECOLOGY AND BEHAVIOR 



Genus Holohalaelurus 



H. regani. Taken on the continental shelf in the southwestern Cape; in 

 Natal on the upper part of the continental slope, as in Mozambique; found 

 at least as far north as Zanzibar. Specimens from the southwest Cape and 

 Natal are distinguishable from each other. 



H. punctatus. Rare in the southern Cape; common on the upper contin- 

 ental slope off Natal and Mozambique. Specimens from East Africa may be 

 conspecific or a related species. 



Genus Cephaloscy Ilium 



C. sufflans. Taken in deep trawls off Natal and southern Mozambique 

 coast. Specimens from Gulf of Aden may be another species. 



Other Galeoid Sharks 



Apart from the carcharhiniform sharks, the galeoid sharks include a number 

 of other species which can be put into two groups: the orectolobiform and 

 the lamniform sharks (after Compagno 1973). 



Orectolobiform Sharks— The bulk of these sharks can be considered 

 as the tropical equivalent of the shallow- water scyliorhinids of more temper- 

 ate regions. Three species fitting in this category occur on the east coast of 

 southern Africa. Only one of these, Stegostoma varium, extends into Natal 

 waters; it is not uncommon in central Natal during the summer months. A 

 sluggish shark attaining about 250 cm in length, it is primarily a mollusk eater 

 although, like most sharks, it readily takes to a diet of fish. A smaller shark, 

 attaining only about 60 cm in length, is Ginglymostoma brevicaudatum, as 

 yet recorded only from shallow water in East Africa. Bearing a remarkable 

 external resemblance to Haploblepharus fuscus of the Natal and southeastern 

 Cape coasts, G. brevicaudatum may occupy a similar niche in its more tropi- 

 cal habitat. Nebrius concolor, a large (3 m), sluggish shark feeding chiefly on 

 crustaceans and cephalopods, is found as far south as the Tongaland coast. 

 The remaining orectolobiform shark is the whale shark, Rhiniodon typus. 

 Well known as the largest of modern fish, attaining a length of about 12 m 

 and feeding by filtration through the gills, R. typus is a tropical species. 

 Quite common along the eastern coast of Africa as far south as Tongaland, 

 specimens are regularly seen off central Natal and occasional sightings are 

 made in the eastern Cape and even in the southwestern Cape. 



Lamniform Sharks— The lamniform sharks occurring regularly off the 

 east coast of southern Africa include three species of Odontaspis, Carcharo- 

 don carcharias, Isurus oxyrinchus, and three species of Alopias. Little is 

 known about the biology or distribution of the latter genus. Alopias vulpinus 

 seems to occur regularly in the southern Cape while A. pelagicus and A. 

 superciliosus have been recorded in central Natal and, in the case of A. 

 superciliosus, in the southern Cape. Carcharodon carcharias was previously 

 shown to be centered basically on the southern and southwestern Cape. 

 Isurus oxyrinchus also seems to inhabit mainly temperate waters, though 



