The platypus has reptilian and mammalian characteristics. The latter include well developed fur, homeothermic endothermy, and mammary glands which nourish young until they are about two thirds adult mass. It has a duck shaped bill, webbed feet, a tail like a beaver, and lay eggs. Adult males are about 50 cm long and weigh 1,600 g and are bigger than females (about 40 cm 900 g respectively). Males have spurs located on the hind legs which can deliver venom which can kill a small animal and has proved extremely painful to humans. Venom production is androgen dependent, but its biological role has not been resolved. The genetics, physiology and biochemistry of platypus have received relatively little attention considering the evolutionary relationship between platypus (and echidnas) and eutherian and marsupial mammals. The platypus genome is no less remarkable, being divided up into large and small chromosomes reminiscent of the macro- and microchromosomes of reptiles and birds. The platypus has ten sex chromosomes (5X, 5Y) that form a chain at male meiosis that links mammal and bird sex determination. However with the absence of the mammalian sex-determining gene SRY sex determination is still a mystery in platypus.
The duck-billed platypus (Ornithorhynchus anatinus) is common in rivers in eastern continental Australia south of Cooktown and east of the junction of the Murray and Darling Rivers, and in Tasmania. However, their distribution is being reduced by human activity, particularly where vegetation from river banks has been reduced and rivers have silted with sand. Platypuses forage for food in rivers and streams (which may be fed directly by melting snow) and shelter in burrows in the banks.
The platypus genome of an animal nicknamed “Glennie” (collected at the Upper Barnard River on Glen Rock Station, New South Wales) was sequenced to a total of 6x whole genome coverage and will serve as the reference genome. The sequencing strategy we utilized, combined whole genome shotgun plasmid, fosmid and BAC end sequences. The draft sequence assembly and a BAC-based fingerprint map with an estimated 12X clone coverage are both available on our platypus genome web site. A comprehensive analysis of the draft sequence assembly is currently in progress. Funding for the sequence characterization of the platypus genome is being provided by the National Human Genome Research Institute (NHGRI), National Institutes of Health (NIH).