Notes on Philippine Sea Snakes of the Genus Laticauda

Abstract

ONE of the most interesting families of snakes is that of the Hydrophidae, or sea snakes. On account of the remoteness of their habitat, and the difficulty of keeping them alive, these marine snakes of the tropical IndoPacific are perhaps less known to herpetologists of the United States than any other group of serpents. The senior author was especially interested in the sea snakes during his stay in the Philippines, and has collected and studied them ever since 1920. For some years the species common in Manila Bay were kept in captivity and their feeding habits observed. A small live eel placed in the tank with sea snakes was bitten, died in a minute or less, and was then swallowed. Part of the interest in snakes at the Philippine Bureau of Science was on account of the little-known marine eels to be obtained from their stomachs. But little study was needed to reveal that in many places these highly venomous reptiles occurred in rather large numbers. For several years the senior author lived opposite old Fort San Antonio de Abad, on the water front at the south end of Manila. It was a frequent occurrence for fishermen to haul a beach seine there, and usually a number of sea snakes would be in the catch. Sometimes more than a hundred would be taken at a single haul. They were usually either Lapemis hardwicki Gray, or Hydrophis inornatus (Gray), or both, though at least three other species were also taken from time to time. Under favorable circumstances sea snakes are abundant in their native habitat. Even those species that seem to be rare are really common if one goes to the right places to search for them. Such places are the rocky and usually cavernous coral limestone islets where sea snakes resort to breed. As an illustration of the actual abundance of some sea snakes as opposed to their apparent scarcity in collections, we cite the case of Laticauda semifasciata (Reinwardt). Although by no means the longest, this species is easily the largest of the East Indian species. A specimen of L. semifasciata 2 meters in length is two or three times as large as an example of Hydrophis cyanocinctus Daudin of the same length. The first Philippine record of Laticauda semifasciata was by E. H. Taylor (1922, 1928), who mentioned a specimen nearly 2 meters in length, at Silliman Institute, Dumaguete, Negros Oriental Province. This was the only specimen of this species that Taylor ever saw in the Philippines, during a decade of reptile collecting. He assumed that it was a rare snake in Philippine waters. About 1923 the senior author discovered that the Riu Kiu Island fishermen operating in the Philippines, were catching numbers of L. semifasciata and eating them. Those not eaten at once were kept alive in unglazed earthen jars until wanted for food. They obtained them at Monja Island, a reef in the entrance to Manila Bay; at the Capones, off the coast of Zambales Province; from outlying rocks in the Cuyo Islands, and off the Palawan coast; and from the north coast of Bohol and elsewhere in the Visayas.