Shaw even took a pair of scissors to the dried skin to check for stitches. There is no universally agreed plural of "platypus" in the English language. Scientists generally use "platypuses" or simply "platypus". Colloquially, the term "platypi" is also used for the plural, although this is technically incorrect and a form of pseudo-Latin ;  the correct Greek plural would be "platypodes".
Early British settlers called it by many names, such as "watermole", "duckbill", and "duckmole". Description Platypus in Broken River, Queensland In David Collins 's account of the new colony — , he describes coming across "an amphibious, mole like" animal.
His account includes a drawing of the animal. It has webbed feet and a large, rubbery duck-like snout. The webbing is more significant on the front feet and is folded back when walking on land. 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; this groove is closed when swimming.
However, the external opening of the ear still lies at the base of the jaw. Platypus venom The calcaneus spur found on the male's hind limb is used to deliver venom. While both male and female platypuses are born with ankle spurs, only the male's spurs deliver venom,    composed largely of defensin -like proteins DLPs , three of which are unique to 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 defense. 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. Information obtained from case histories and anecdotal evidence indicates the pain develops into a long-lasting hyperalgesia a heightened sensitivity to pain that persists for days or even months.
The female platypus, in common with echidnas, has rudimentary spur buds that do not develop dropping off before the end of their first year and lack functional crural glands. Since only males produce venom and production rises during the breeding season, it may be used as an offensive weapon to assert dominance during this period. Monotremes for the other species, see Echidna are the only mammals apart from at least one species of dolphin  known to have a sense of electroreception: The platypus' electroreception is the most sensitive of any monotreme.
The electrosensory area of the cerebral cortex is contained within the tactile somatosensory area, and some cortical cells receive input from both electroreceptors and mechanoreceptors, suggesting a close association between the tactile and electric senses. Both electroreceptors and mechanoreceptors in the bill dominate the somatotopic map of the platypus brain, in the same way human hands dominate the Penfield homunculus map. This would explain the characteristic side-to-side motion of the animal's head while hunting, seen also in the Hammerhead shark while foraging.
The cortical convergence of electrosensory and tactile inputs suggests a mechanism that determines the distance of prey that, when they move, emit both electrical signals and mechanical pressure pulses. The platypus uses the difference between arrival times of the two signals to sense distance. The eyes also contain double cones , which most mammals do not have.
The corneal surface and the adjacent surface of the lens is flat while the posterior surface of the lens is steeply curved, similar to the eyes of other aquatic mammals such as otters and sea-lions.
A temporal ear side concentration of retinal ganglion cells , important for binocular vision, indicates a role in predation , while the accompanying visual acuity is insufficient for such activities. Furthermore, this limited acuity is matched by a low cortical magnification , a small lateral geniculate nucleus and a large optic tectum , suggesting that the visual midbrain plays a more important role than the visual cortex like in some rodents.
These features suggest that the platypus has adapted to an aquatic and nocturnal lifestyle, developing its electrosensory system at the cost of its visual system; an evolutionary process paralleled by the small number of electroreceptors in the short-beaked echidna , which dwells in dry environments, whilst the long-beaked echidna , which lives in moist environments, is intermediate between the other two monotremes. Platypus swimming Swimming underwater at Sydney Aquarium , Australia The platypus is semiaquatic, inhabiting small streams and rivers over an extensive range from the cold highlands of Tasmania and the Australian Alps to the tropical rainforests of coastal Queensland as far north as the base of the Cape York Peninsula.
Mortality rates for adults in the wild appear to be low. Low platypus numbers in northern Australia are possibly due to predation by crocodiles. When swimming, it can be distinguished from other Australian mammals by the absence of visible ears. Recovery at the surface between dives commonly takes from 10 to 20 seconds. It uses cheek-pouches to carry prey to the surface, where it is eaten. This was not confirmed until , when William Hay Caldwell was sent to Australia, where, after extensive searching assisted by a team of Aborigines , he managed to discover a few eggs.
The species exhibits a single breeding season ; mating occurs between June and October, with some local variation taking place between different populations across its range. The female softens the ground in the burrow with dead, folded, wet leaves, and she fills the nest at the end of the tunnel with fallen leaves and reeds for bedding material. This material is dragged to the nest by tucking it underneath her curled tail. The incubation period is divided into three phases.
The yolk is absorbed by the developing young. This is in comparison to meroblastic division in birds and platypuses, which causes the ovum to split but not completely. This allows the yolk, which contains the embryo, to exchange waste and nutrients with the cytoplasm. Although possessing mammary glands , the platypus lacks teats. Instead, milk is released through pores in the skin. The milk pools in grooves on her abdomen, allowing the young to lap it up.
During incubation and weaning, the mother initially leaves the burrow only for short periods, to forage. When doing so, she creates a number of thin soil plugs along the length of the burrow, possibly to protect the young from predators; pushing past these on her return forces water from her fur and allows the burrow to remain dry.