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Andaman Sea Coast, Thailand  Our field site on the Andaman Sea coast of southern Thailand includes extensive mangrove forest and abundant mud lobster mounds. The mud lobster (Thalassina anomalus) is an important mangrove crustacean that filters the mud for food as it burrows. Material that cannot be digested is deposited outside the lobster's burrow entrance and as it accumulates a mound is built. The mounds at this site approach two meters in height and have a circumference that is three to four meters. Each of these mounds supports one or more mangrove trees of varying sizes. An assemblage of small goby fish (mudskippers), crabs, shrimp, and a variety of other invertebrates colonizes these mounds forming a complex community that is washed with sea water twice a day as the tides rise and recede. The roots of the vegetation stabilize the soil, and a series of tidal creeks surrounds the mounds. At low tide some pools of water are trapped in low areas and we observed sea anemones and octopus dwelling in these forest pools. 
This environment supplies numerous hiding places for homalospine snakes as well as an abundant food supply. We speculate that the apparent rarity of some marine homalopsines such as Gerard's water snake (Gerarda prevostiana) is due to their use of the mud lobster mounds as hiding and foraging sites. This microhabitat makes them exceedingly difficult to find. At a location along the Singapore coast we filmed this snake moving in and out of the lobster mounds after dark, and we have excavated a Gerard's water snake from a lobster mound burrow. Additionally, Gerard's water snake has a distribution that ranges from Bombay, India eastward to the Philippines; a distribution that complements that of the mud lobster.
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