The Platypus (Ornithorhynchus anatinus) – the Egg Laying Mammal
Ornithorhynchus anatinus commonly known as the platypus or duck-billed platypus is the only platypus species that is still known to be a living species.
This photograph is of a Duck-Billed Platypus which has characteristics of both mammal and reptile
Background
The duck-billed platypus is the only living platypus species, endemic to Australia. Though can be found in the waters of Tasmania, which is around 150 miles of the coast of Australia.
The habitat that platypus forages in freshwater bodies such as stream, lakes and ponds. But dwell in burrows in the earth banks, which is also where they nest. They have however resting been found in low density vegetation. The platypus feed on a range of insect larvae, invertebrates, small fish and tadpoles.
The platypus is an average of 40-60 cm long and living up to 21 years in the wild but only 20 in captivity. Male platypus’ have spurs which can produce venom which give the victim excruciating pain with long-lasting sensitivity.
This image shows a duck-billed platypus which is kept at the Natural History Museum
The Importance of the Platypus
The Platypus biology is between a mammal and reptile
The morphology of the platypus has distinct mammal and reptile features:
The bill has the appearance of a ducks bill but it is soft containing nerves which are used by the platypus in the water to find food and navigate.
The feet are webbed with non retracting claws which are used for swimming and digging
On the other hand the platypus has fur which is waterproof like that of a polar bear.
The tail is mainly fatty tissue which is used as a fat store.
The biological characteristics which cannot be seen are that the skeleton resembles both that of marsupial mammal and reptile, most significantly the legs splay out which is a feature of reptiles however role in sockets like mammals.
Reproduction of the platypus is unusual egg laying
The egg laying of the platypus is rare, it took scientist 93 years from the discovery of the platypus to observe this. The egg laying is a reptilian behaviour however the investment into their young and lactation is mammalian behaviour, which last up to four months.
The platypus could be considered a missing link between reptiles and mammals which still lives today
The interesting thing about the platypus is that not all its reptilian features evolved from reptiles, the venom which it produces in the spurs actually were a produce of convergent (a trait in two species which are not related, it has no lineage).
However the lactating was preserved from their common ancestors ancient mammals which branched out around 160 million years ago.
Which questioned the other reptilian characteristics, research is still being done to established the lineage of the platypus.
In the journal Nature in 2008 it was reported through genome sequencing that 80% of the gene were common to that of mammals however two genes were found which have only been found in amphibians, birds and fish.
This photograph shows the lag of the holotype/type (the first ever studied) specimen which is housed at the Natural History Museum
Photographs were obtained from the Natural History Museum, London
Information collated and found at:
Natural History Museum – ornithorhynchus anatinus (platypus)
Natural History Museum – Platypus genome sequenced
Nature – Genome analysis of the platypus reveals unique signatures of evolution
The 24 Natural Treasures of Christmas 
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