The spurs are used offensively by bringing them together in the ventral midline with powerful jabbing movements. Male platypuses possess a crural system consisting of a venom gland on the dorsal aspect of the thigh, connected by a duct to a hollow keratinous spur on the tarsus. The platypus has a lizard-like gait on land. The hind feet act as a rudder during swimming and an anchor during burrowing. When walking or burrowing, the webbing extensions are folded back under with the claws out. The pes is turned caudolaterally Webbing on the fore limbs extends beyond the claws to form fan-shaped paddles for swimming. There are two pairs of pentadactyl limbs, with claws and webbing on the digits of the manus and pes. Their ears have an obvious external ear canal, but little pinna development. A nictitating membrane is present (unlike the echidna). Platypuses have poor vision and their eyes are tilted up to scan for predators. Photo: Taronga Zoo.īoth eyes and ears are in a groove which closes when diving. The pores in the skin of the bill and frontal shield (3) are the sites of the electro-receptors and mechano-receptors. The dorsal nostril position allows the platypus to breathe while most of its body is underwater.įigure 6.1 The head of the platypus. The platypus snout is covered by soft leathery pigmented skin ( Fig. Females may also lose significant hair on the dorsal surface of the tail during the breeding season due to pugging of burrows (the process of building a mud partition within the tunnel). Platypuses moult seasonally with patchy loss of guard hairs. The platypus has a streamlined body that is compressed dorsoventrally and is covered by fur except for the bill and feet. Juvenile platypuses disperse, moving away from their natal stream. They depend on relatively undisturbed stream banks to support their resting and nesting burrows and show site fidelity with riverine home ranges of up to 7 km ( Gardner & Serena 1995). In some locations they are regularly diurnal. Platypuses have a solitary nature (except when breeding or suckling) and are mainly nocturnal, but may be crepuscular during the winter. Legal protection of platypuses was first given in Victoria in 1892, with all other states following suit by 1912 ( Grant 1995). Prior to their protection, thousands of platypuses were killed for the fur trade. They occupy a wide range of habitats, from tropical to cool temperate and pristine to degraded, and are classified as common but are potentially vulnerable to environmental perturbation ( Grant & Temple-Smith 1998). Platypuses occur in freshwater streams and lakes along the eastern seaboard of Australia from Cooktown to Tasmania, mainly east of the Great Dividing Range (west only in permanent rivers) and were introduced to Kangaroo Island in 1940. (2004a) recorded a female platypus surviving 21 years in the wild. Monotremes are long-lived for small mammals and have been maintained for up to 21 years in captivity. Bergmann’s rule applies to the platypus, with larger animals found in the cooler parts of their range ( Dunn 1949). Males are larger than females (45–63 cm long and weigh 1000–3000 g, females are 39 – 55 cm long and weigh 700–1750 g) and can be distinguished from adult females by the presence of a spur on the medial side of the tarsus ( Grant 1989 Connolly & Obendorf 1998). The Family Ornithorhynchidae contains one extant species, the platypus (Ornithorhynchus anatinus). The monotremes (‘one hole’) possess a common opening, the cloaca, for the reproductive, urinary and digestive systems, and the testes are abdominal (testicond). The platypus belongs to the Order Monotremata, the egg-laying mammals. The platypus is a highly specialised semi-aquatic, burrowing, carnivorous egg-laying mammal that is so well-adapted that it has survived relatively unchanged since the time of the dinosaurs.
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