318.
Platypus
(Ornithorhynchus anatinus)
LC
Overview

The notion of the duck-billed platypus possessing a bird-like horny bill originated from examinations of dried specimens. The bill is actually soft, moist and leathery and also highly sensitive. The platypus is one of the the most evolutionary distinct mammals alive today. It is the only representative of an entire family of mammals dating back to the Cretaceous period (146-65.5 millian years ago), and one of only five species in the order Monotremata. Monotremes differ from all other mammals in that they lay eggs covered by a shell that hatch outside the mother's body. Monotremes are also unique in that they have only a single passage, the cloaca, for both excretion and reproduction.

Urgent Conservation Actions
Although the platypus is not currently threatened, efforts should be made to reduce the effects of human activities on the species and its habitat.
Distribution
Australia: New South Wales, Queensland, south eastern South Australia, Tasmania and Victoria.
Associated Blog Posts
18th May 08
Scientists have recently sequenced the genome of the most Evolutionarily Distinct mammal species, the platypus (Ornithorhynchus anatinus), in order to stud...  Read

Media from ARKive
ARKive image - Head and bill of a platypus
ARKive video - Platypus - overview
ARKive image - Platypus crawling in a shallow stream
ARKive video - Infant platypus in burrow and lactation
ARKive image - Platypus diving
ARKive video - Young platypuses growing in the burrow and rubbing bills with parent
ARKive image - Female platypus swimming underwater
ARKive video - Platypus swimming in winter habitat
ARKive video - Platypus hunting and feeding on aquatic invertebrates
ARKive image - Platypus swimming
ARKive video - Cormorant feeding on invertebrates flushed out by platypus hunting
ARKive image - Platypus at the surface chewing invertebrates in cheek pouch from last dive
ARKive video - Male platypus grooming at night, attacked by another male
ARKive image - Platypus feeding at the surface
ARKive video - Platypus swimming in riverine habitat and courting
ARKive image - Platypus swimming underwater in a river
ARKive video - Platypus courtship and copulation
ARKive image - Platypus drying after leaving the water
ARKive video - Platypus collecting nesting material and maintaining burrow
ARKive image - Close up of platypus fur
Evolutionary Distinctiveness
Order: Monotremata
Family: Ornithorhynchidae

The duck-billed platypus is one of the most evolutionary distinct mammal alive today. It is the only representative of an entire family, Ornithorhynchidae, dating back to the Cretaceous period (146-65.5 millian years before present). The other more recent members of the family became extinct during the Oligocene and Miocene (34-5.3 million years ago).

 

The platypus belongs to the order Monotremata. Monotremes are the most distinct of all the orders of living mammals. Some authorities place them in a subclass with extinct lineages separate from all other living mammals. Others have even considered monotremes to be reptiles. There are only five species of montreme in the world today: four species of echidna and the duck-billed platypus.

Monotremes differ from all other mammals in that they lay eggs covered by a shell that hatch outside the mother's body. Monotremes are also unique in that they have only a single passage, the cloaca, for both excretion and reproduction. The duck-billed platypus is an integral part of the biodiversity of many Australian freshwater ecosystems. Its conservation is of considerable importance because of its evolutionarily distinctiveness, unique features and the niche it occupies.

Description
Size: 
Length 400-600mm from head to tail
Long tail measures 370-470mm
Weight: Adult weight is between 0.5 and 2.0kg
The upper coat colour can vary from deep orangey brown to blackish brown. The underside of the coat ranges from white to orangey yellow. The coat is double-layered and traps air as insulation. This makes the platypus buoyant when under water. The body is streamlined, with the tail flattened resembling that of a beaver. The bill is elongated and covered in moist soft skin dense in sensitive nerve endings. Adults do not have teeth and instead chew their food using horny plates on the jaw with the aid of the tongue. Short strong legs and broad webbed feet equipped with tough claws make the platypus adept at both digging and swimming.
Ecology

The duck-billed platypus is usually active in the early morning and late evening when it leaves its burrow to search for food. It swims along the bottom of freshwater streams and lakes probing at mud and gravel beds with its highly sensitive bill. Research has shown that electro-receptors in the bill detect the muscle activity of prey. A typical diet consists of a variety of freshwater organisms including crayfish, shrimp, the larvae of water insects, snails, tadpoles, worms and small fish. The home ranges of males overlap those of several females. The male will maintain a burrow for both sexes during the breeding season.

 

The males posses hollow spurs linked to poison glands. It has been suggested that these are used primarily in fights between males during the breeding season. The female lays eggs in a different type of burrow that she constructs herself. In this burrow the eggs are incubated and hatch. The babies are tiny, blind and naked. They remain in the burrow for about four months during which time the mother provides them with milk. Females begin breeding at 2 or 3 years and typically lay 2 eggs at a time. In the wild platypuses have been recorded as living up to 13 years.

Habitat
Freshwater streams, lakes and lagoons. Burrows are constructed in the banks.
Distribution
Australia: New South Wales, Queensland, south eastern South Australia, Tasmania and Victoria. An introduced population is present on Kangaroo Island off the coast of South Australia.
Population Estimate
Not known. The platypus is common throughout its original range, with the exception of South Australia but its abundance is not easily measured.
Population Trend
Not known.
Status
The duck-billed platypus is classified as Least Concern in the 2007 IUCN Red List of Threatened Species.
Threats

The platypus was hunted intensively for its fur until the early 20th century. Until about 1950 it was also subject to accidental drowning in the nets used by inland fisheries. The species has recovered well from these threats, mainly due to an effective government conservation programme.

Other threats are now presenting problems for the platypus. Habitat disruption caused by dams, irrigation projects and pollution are threatening Australian freshwater systems. Accidental bycatch in inland fishing gear continues to result in some mortality. In spite of these threats, the species has so far continued to inhabit and reproduce in considerably degraded environments. The present distribution of the platypus appears to be little altered from pre-European times. There are almost certainly no naturally occurring populations in South Australia where it once occurred, and its distribution has decreased in the lower areas of the Murray and Murrumbidgee River systems in Victoria and New South Wales.  It is probable that commercial and illegal fishing operations within the distribution of platypuses in the lower Murray and Murrumbidgee rivers, are suppressing platypus numbers. A study indicated that the legal fishing nets used in the industry are less of a threat to platypuses than the use of illegal nets used by poachers.

Although the platypus is considered to be common throughout its current distribution, its abundance is difficult to measure and therefore its future conservation status is not easily predicted. Several studies have reported fragmentation of platypus distribution within individual river systems. This has been attributed to poor land management practices leading to stream bank erosion, sedimentation of water bodies and the loss of vegetation at areas adjacent to water courses. There is also currently evidence for the adverse effects of river regulation, introduced species, poor water quality and disease on platypus populations, but these have been little studied.

Conservation Underway

The platypus is protected by legislation in all the States of Australia where it occurs. Effective government conservation efforts have allowed the numbers of this species to increase from previous reductions. Current fishing regulations have provided a good deal of protection for the species. Regulations include the use of nets with larger mesh size since 1950, as well as other modifications in fishing gear.

Platypuses have been introduced to two streams on Kangaroo Island off the coast of South Australia: Rocky River and Breakneck River. These populations appear to be thriving without any adverse consequences for the native wildlife on the island.

Conservation Proposed

Investigations into the biology of the platypus and interactions with human activities have been noted by scientist as being research priorities. Suggested management priorities include the development and implementation of strategies aimed at reducing the effects of human activities on the platypus and its habitat. Research is continuing into the design of platypus friendly fishing methods with a particular focus on New South Wales where the platypus population appears to be suppressed by fishing activity.

Other suggestions include restricting some fishing activities to estuarine areas where platypuses are seldom found, the provision of air spaces and escape holes in eel traps and prohibiting eel trapping in areas where platypuses are known to occur. Stringent law enforcement would largely protect platypus populations in the inland rivers from illegal fishing activity. Investigations are underway to assess whether Scott creek, a stream in the Mount Lofty Ranges, could support an introduced platypus population. The species has been extinct from the area for about 100 years. Further assessment is needed of the appropriateness of Scott Creek for platypus reintroduction.  For example, it is necessary to assess the suitability of banks and permanent pools and the risk of predation by foxes.

Links
References

Australasian Marsupial & Monotreme Specialist Group. 1996. Ornithorhynchus anatinus. In: IUCN (2007). 2007 IUCN Red List of Threatened Species. Downloaded on 13 November 2007.

 

Grant, T. R. 1993. The past and present freshwater fishery in New South Wales and the distribution and status of the platypus Ornithorhynchus anatinus. Australian Zoologist 29 (Special Edition) 1-2: 105-113.

 

Grant, T. R., Lowry, M. B., Pease, B., Walford, T. R., Graham, K. 2004. Reducing the by-catch of platypuses (Ornithorhynchus anatinus) in commercial and recreational fishing gear in New South Wales. Proceedings of the Linnean Society of New South Wales 125 : 259-272.

 

Griffiths, M. (1978) The biology of monotremes. Academic Press, New York, p367.

 

Grant, T.R and Temple-Smith, P.D. 2003. Conservation of the platypus, Ornithorhynchus anatinus: Threats and challenges. Aquatic Ecosystem Health & Management 6 (1) : 5-18.

 

Nowak, R. M. (ed.) 1999. Walkers Mammals of the World. Sixth edition. The Johns Hopkins University Press, Baltimore and London.

 

Scheich, H., Langer, G., Tidemann, C., Coles, R. B., and Guppy, A. 1986. Electroreception and electrolocation in platypus. Nature 319:

 

401-2 Souter, N. J. and Williams, W. D. 2001. A comparison of macroinvertebrate communities in three South Australian streams with regard to reintroduction of the platypus. Transactions of the Royal Society of South Australia 125 (2) : 71-82.

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