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| Graceful Small Headed Sea Snake , Microcephalophis (=Hydrophis) gracilis (Shaw, 1802). Photograph of museum specimen from the Gulf of Thailand. Widespread, ranging from the Persian Gulf , India, Sri Lanka, Myanmar, Indochina, Indonesia (Sumatra and Java) eastward to southern China, Australia, and Melanesia. Adult females reach 1.025 m, males are smaller. Females give birth to 1-16 young. |
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Yellow Lipped Sea Krait, Laticauda colubrina (Schneider, 1799). This series of photographs was taken on a small offshore rock off the coast of Kota Kinabaula, Sabah, Malaysia (Island of Borneo). While this snake is often called a "sea snake," this name is somewhat misleading. L. colubrina body size averages about 1 m, and reports of snakes up 2 m long are in the literature, however the maximum documented sized is probably 1.652 m. Females tend to be larger than males. The Yellow Lipped Sea Krait is probably the most terrestrial of the five species of Laticauda. It will cross roads, climb on to boats, and spend considerable time out of water digesting food and searching for mates. All Laticauda have wide ventral scales, the kind of ventral scales found in most terrestrial colubrids (see photo of shed skin). These wide scales with a free posterior margin are useful for crawling about on land. Most other sea snakes rarely, if ever, come ashore and they have greatly reduced ventral scales. The snakes shown were found on the offshore rock in the bottom photo. It was low tide, and it was possible to walk to the rock and explore it. Most snakes had congregated near the top in the vegetation. Laticauda seems to prefer these small islets and offshore rocks to being on the actual coast of an island, or continent. Perhaps these habitats have fewer predators. Offshore rocks may support dense congregations of Laticauda, these may be mating aggregations. The Yellow Lipped Sea Krait appears to have a very specialized diet, feeding only on moray eels. However, captives are known to take other species of fish but, moray eels appear to be the only prey taken in nature. Male Sea Kraits take smaller eel species than do females. Laticauda hunt morays on coral reefs and then proceed to a islet to digest the prey. The morays taken may be 60-70% of the snakes body weight, and yet they seem to digest their meals quickly, with feces being produced within two days after eating. This is unusual for snakes which may require a week or more to digest a large meal. Sea Kraits lay eggs, however rumors persist about one species giving birth to live young. Females put about 17-26% of their body mass into egg production. Populations near the equator seem to reproduce year round, while populations at higher latitudes reproduce seasonally. Female Sea Kraits may become more secretive when they are gravid and move to more protected microhabitats. The eggs are deposited in caves and rock crevices and sometimes these locations are below the high tide mark, suggesting that the eggs may be able to survive submergence (or eggs that are submerged, simply may not survive). Incubation for one clutch of L. colubrina eggs was 91 days. Upon hatching male Sea Kraits are larger and heavier than females, this is surprising because adult males are smaller and weigh less than females. The age of sexual maturity has been estimated for the New Caledonian population at 1.5 years, with females being able to lay eggs in their second year of life. Predation on Sea Kraits has not been studied, but crabs are suspected to be major predators on hatchlings. Birds of prey, such as the White Bellied Sea Eagle will pick Sea Kraits out of the water. The terrestrial tick, Amblyomma nitidum will feed on Sea Kraits (see photo) and it apparently has the ability to with stand submergence in sea water. Sea Kraits can stay submerged voluntarily for at least 50 minutes. Like most colubroid snakes they have only the right lung (the left lung has degenerated), and like some other snakes they have the ability to absorb oxygen from the water through their skin. Sea Kraits drink freshwater. They will drink rainwater off their body. They may also drink rainwater from the surface of rocks or from the lens of freshwater that accumulates after a rain on the surface of the sea. It is unknown if they can survive without a supply of freshwater. Sea Kraits are a fascinating group of snakes that illustrate one attempt by snakes to evolve a marine life style. More about these snakes can be found in Alan Greer's Book, The Biology and Evolution of Australian Snakes. 1997. Surrey Beaty & Sons, Ltd. And, in Ivan Ineich and Pierre Laboutes' book Sea Snakes of New Caledonia. IRD Editions. |
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| Eastern Tiger Snake, Notechis scutatus (Peters, 1861). Photographed in an Australian collection. Eastern Tiger Snakes inhabit shrub and woodland habitats in southeastern and southwestern Australia and Tasmania. They have also colonized the islands in the Bass Straight. While these have been regarded as separate (island) species recent work has suggested that they should be regarded as one species. This snake is semi-aquatic. Mainland populations feed on frogs, the Chappel Island population feeds on mutton bird chicks, and populations on other island in the Bass Strait feed on lizards. Interestingly, the Chappel Island population has snakes that grow to a much larger size than the other populations. Tiger Snakes give birth to litters of up to 64 young. When disturbed it raises its fore body, flattens its head and neck and threatens the potential predator. |
| This clade contains both terrestrial, semi-aquatic, and aquatic snakes in 44 genera holding 177 species. Molecular studies suggest that marine lifestyles in snakes evolved at least three times from within this family. The sea kraits (Laticauda)have paddle like tails, wide ventral scales, lay eggs, have terrestrial parasites and spend considerable time on land. Sea Snakes in the genera Hydrophis, Microcephalophis, etc. have narrow ventral scales; a compressed body; a paddle-like tail; are viviparous; and rarely, if ever, leave the water. Then, there are the terrestrial Hydrophiidae that seldom enter the water and live in forests, grasslands, or deserts. Keogh et al. (1998 Molecular Phylogenetics and Evolution 10:67-81) consider the Australian terrestrial Hydrophiidae derived from a Miocene invasion of an Asian ancestor rather than the Gondwanaland radiation previously hypothesized. |