AUSTRALIAN BIODIVERSITY RECORD - Calodema

Australian Biodiversity Record, 2007 (8): 1-124week keel or small line of tubercles, and in 46-63 rows at mid-body (with females having aslightly higher mid-body count than males); ventrals longitudinally divided, strongly imbricate,and numbering 226-286 (similar in males and females), each being only slightly wider thanthe adjacent body scales, and in mature specimens forming a distinct mid-line keel at thepoint of overlap of each ventral scale; preanal scales enlarged. It is said to attain a maximumtotal length of about 2 m., although 1.5 m. would be the usual maximum size - and femalestend to be somewhat larger than males, and have longer snout vent lengths. In Australianwaters a maximum snout-vent length of around 1.4 m. is achieved, with females being largerthan males which are seldom much over 1.2m. This is nevertheless an extremely largespecies, evidenced by an exceptional specimen 1.6 m. in total length that had a girth of 260mm. - making it probably the bulkiest of sea snakes. Variation in morphology suggests thatthis species may be composite.Distribution: Largely confined to tropical Australian seas, being found off the coasts ofQueensland, Northern Territory and Western Australia, and occasionally as far south as thewaters off Wollongong, New South Wales. Also widely known from the Arabian Gulf, acrossSouth East Asia, mainly from Pakistan, through Indonesia to New Guinea.Habitat: Mainly inhabits relatively shallow continental shelf areas near coral reefs with sandybottoms as well as around muddy river delta outflows and estuarine areas usually in watersfrom about 4m to 25m depth - but usually less than 10 metres.Biology/Ecology: This is both a diurnal and nocturnal species that feeds on a variety of smallfishes, with prey being actively hunted around coral. It may be often observed basking at thesurface in relatively turbid waters near rivers and is known to inhabit tidal waters somedistance up rivers as well. Specimens are occasionally found with growths of algae, barnaclesand bryozoans on its skin, and large infestations of nematodes may be carried in thestomach. It appears to have seasonal reproductive habits, but only limited data is presentlyavailable. Females carrying oviducal young have been found in mid-summer, and it ispresumed that the young are born in late Autumn. Litter sizes vary from 4 to 20, with anaverage of 10 to 14 being usual - juveniles are around 400 mm in length at birth.Toxicity: This is a potentially dangerous species as its venom is highly toxic to humans and itwill readily attempt to bite if handled or harassed. Caution should definitely be exerted withthis species, because on occasion it has been known to attack divers with little warning orprovocation. With its relatively large teeth and a large amount of venom, a wet-suit should notbe considered as adequate protection from penetration by the fangs of an adult snake.Similarly, specimens landed on trawlers vigorously bite anything within range, includingfishing gear, and those handled by researchers readily try to bite if restrained or handledroughly. If one is unfortunate enough to receive a bite from this powerful species, urgentmedical attention should be sought - even though to date there have been no known humanfatalities recorded against this species.Survival Status: Protected under the New South Wales National Parks and Wildlife Act (1974)but not listed in that State as a Threatened Species in any of the Schedules of the NSWThreatened Species Conservation Act (1995). Also protected under the Qld NatureConservation Act (1992), the Territory Parks and Wildlife Conservation Act (1998) and theWA Wildlife Conservation Act 1950 (as amended). Listed as a Marine Protected Speciesunder the Australian Environmental Protection and Biodiversity Conservation Act (1999).Probably not under threat, but its restricted distribution in Australian waters could potentiallymake it vulnerable in some parts of its range.Etymology: The name 'stokesii' honours English explorer and naturalist Admiral John LortStokes, who collected the species in 1840.25