Ecology, systematics and biogeography of sea snakes

Abstract

The sea snakes are a diverse group of marine reptiles compnsmg 64 species assembled into four lineages, Aipysurus, Laticauda, Ephalophis and Hydrophis groups. An estimated 40,000 sea snakes of the Aipvsurus and Hydrophis groups inhabited Ashmore Reef, Eastern Indian Ocean. Male and female sea snakes of the four lineages displayed sexually dimorphic and geographic variation in their scale patterns. None showed ontogenetic variation in scalation. Cladistic analysis using diverse anatomical, scalation and behavioural characters demonstrated that the sea snakes were closely related to, and within, the clade of Australian-Melanesian terrestrial elapids. The laticaudine lineage was basal to the other sea snake lineages. The hydrophine and ephalophine lineages were more closely related to each other than they were to either of the other two lineages. Each of the four lineages displayed differing biogeographical scenarios. The Aipysurus group were largely restricted to Australian continental shelf areas with only two species found in Asian waters. The Laticauda group displayed a north-south northern Pacific Ocean species assemblage and an east-west Indian Ocean and southern Pacific Ocean distribution with local endemism. This distribution is most likely attributable to dispersal scenarios. The Ephalophis group was confined to northern Australia and southern New Guinea. The Jfydrophis group had Australian and Asian species with some species common to both continents. Scale modifications enabled Emydocephalus to feed on fish eggs and enabled Aipysurus foliosquama to inhabit the reef flat at low tide by using evaporative cooling to withstand high water temperatures. Scales of most sea snake species had reduced microdermatoglyphic patterns when compared to those of the more aquatic members of the terrestrial elapids, colubrids, and pythons. Acaf,-1,ptophis peronii had enhanced patterns and spines on the scales, which provided friction during the forward-strike employed in feeding. 

Date of Award	2003
Original language	English
Supervisor	Charles Webb (Supervisor) & Helen Larson (Supervisor)