The platypus (Ornithorhynchus anatinus), also known as the platypus, is a semi-aquatic egg-laying mammal endemic to eastern Australia, including Tasmania. The platypus is the only extant species of the family Ornithorhynchidae and genus Ornithorhynchus, but many related species appear in the fossil record. Along with four species of echidna, it is one of five extant species of monotremes, mammals that lay eggs instead of giving birth to live offspring. Like other monotremes, the platypus has a sense of electrolocation, which it uses to detect prey underwater when its eyes, ears, and nostrils are closed. Male platypuses have spines on each hind leg that secrete highly painful venom, making them one of the few species of venomous mammals.
Classification of Ornithorhynchus (Platypus)
- Phylum :- Chordata (Dorsal tubular nerve cord, notochord and gill-slits present.)
- Group :- Craniata (Definite head, Cranium with brain present.)
- Sub phylum :- Vertebrata (Vertebral column present.)
- Division :- Gnathostomata (Jaws and paired appendages present.)
- Super Class :- Tetrapoda (Paired limbs, lungs, cornified skin and bony skeleton.)
- Class :- Mammalia (Body covered with hairs. Females have mammary glands.)
- Sub Class :- Prototheria (Egg-laying mammals.)
- Order :- Monotremata
- Genus :- Ornithorhynchus
Geographical distribution
Found in South Eastern Australia and Tasmania. Triassic to Recent.
Habit and habitat
It is a native of rivers, pools and creeks. It burrows to 12 to 15 metres along the river banks. It feeds on fresh-water invertebrates, carried in cheek pouches.
General Characteristics of Ornithorhynchus (Platypus)
- Commonly called as duck-billed-platypus.
- It measures about 50 cm in length having fine short fur, dark brown colour and combines the characters of a duck with a mammal.
- Body is divided into head, thick trunk and tail. Body and tail contain soft hairs.
- Head distinct. Upper jaw produced to form a flattened beak which is covered with a smooth, hairless skin that forms a free fold at the base of the beak. Head contains nostril mouth and external ear opening.
- Adult has no teeth. Jaws covered with horny plates. Pinnae absent.
- Forelimbs and hind limbs have 5 digits, web and clawed toes.
- Hind limb has horny spur. Tail is flattened and adapted for swimming.
- Coracoid and precoracoid present. T -shaped interclavicle.
- Eyes small having nictitating membrane. Mammary glands without nipples.
- Cloaca present. Ureters open in dorsal wall of urinogenital passage. Testes abdominal, penis conducts only sperms. Oviducts distinct, uterus or vagina absent.
- Female makes nest of roots and leaves during spring in burrows, lays 1-3 eggs. About 0.5 cm long young one is hatched. It nurses by lapping up milk secreted by scattered mammary glands on the abdomen of female.
Special Features
Ornithorhynchus is an egg-laying mammal and exhibits reptilian, mammalian and intermediate characters. Reptilian features are urinogenital system, precoracoids, absence of pinna and corpus collosum. Mammalian features include hair, diaphragm, 4-chambered heart, 3-ear ossicles, etc. Intermediate features include mammary glands without nipples, acromion spines in the scapulae and body temperature between 25 – 28°C is imperfect thermoregulator.
Identification
Since this mammal has flat bill and above features, hence it is Omithorhynchus
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