PLATYPUS-EGG LAYING MAMMAL

The Platypus  sometimes referred to as the duck-billed platypus or a egg laying mammal, is a semiaquatic egg-laying mammal endemic to eastern Australia, including Tasmania. The platypus is the sole living representative of its family Ornithorhynchidae and genus Ornithorhynchus. 

Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young. Like other  monotremes it senses prey through electrolocation. It is one of the few species of venomous mammals, as the male platypus has a spur on the hind foot that delivers a venom capable of causing severe pain to humans. 

The unique features of the platypus make it an important subject in the study of evolutionary biology, and a recognisable and iconic symbol of Australia.  

Until the early 20th century humans hunted the platypus for its fur, but it is now protected throughout its range. Although captive-breeding programs have had only limited success, and the platypus is vulnerable to the effects of pollution, it is not under any immediate threat.The body and the broad, flat tail of the platypus are covered with dense, brown fur that traps a layer of insulating air to keep the animal warm.The fur is waterproof, and the texture is akin to that of a mole.The platypus uses its tail for storage of fat reserves(an adaptation also found in animals such as the Tasmanian devil). The webbing on the feet is more significant on the front feet and is folded back when walking on land. The elongated snout and lower jaw are covered in soft skin, forming the bill. The nostrils are located on the dorsal surface of the snout, while the eyes and ears are located in a groove set just back from it. 

                  It weight varies considerably from 0.7 to 2.4 kg (1.5 to 5.3 lb), with males being larger than females; males average 50 cm (20 in) in total length, while females average 43 cm (17 in),  groove is closed when swWhile both male and female platypuses are born with ankle spurs, only the male's spurs deliver venom,composed largely of defensin like protein(DLPs), three of which are unique to the platypus. The DLPs are produced by the immune system of the platypus. The function of defensins is to cause lysis in pathogenic bacteria and viruses, but in platypuses they also are formed into venom for defence. Although powerful enough to kill smaller animals such as dogs, the venom is not lethal to humans, but the pain is so excruciating that the victim may be incapacitated.The platypus is an excellent swimmer and spends much of its time in the water foraging for food. When swimming, it can be distinguished from other Australian mammals by the absence of visible ears. Uniquely among mammals, it propels itself when swimming by an alternate rowing motion of the front feet; although all four feet of the platypus are webbed, the hind feet (which are held against the body) do not assist in propulsion, but are used for steering in combination with the tail.

                 The species is endothermic, maintaining its body temperature at about 32 °C (90 °F), lower than most mammals, even while foraging for hours in water below 5 °C (41 °F).Dives normally last around 30 seconds, but can last longer, although few exceed the estimated aerobic limit of 40 seconds. Recovery at the surface between dives commonly takes from 10 to 20 seconds.

When not in the water, the platypus retires to a short, straight resting burrow of oval cross-section, nearly always in the riverbank not far above water level, and often hidden under a protective tangle of roots.The average sleep time of a platypus is said to be as long as 14 hrs per day, possibly because it eats crustaceans, which provide a high level of calories    

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