The family Potoroidae
The long-nosed potoroo (Potorous tridactylus)
Long-nosed potoroo видео
Potoroidae is a family of marsupials, small Australian animals known as bettongs, potoroos, and rat-kangaroos. All are rabbit-sized, brown, jumping marsupials and resemble a large rodent or a very small wallaby.
Taxonomy
The potoroids are smaller relatives of the kangaroos and wallabies, and may be ancestral to that group. In particular, the teeth show a simpler pattern than in the kangaroo family, with longer upper incisors, larger canines, and four cusps on the molars. However, both groups possess a wide diastema between the incisors and the cheek teeth, and the potoroids have a similar dental formula to their larger relatives:
Dentition
(3.0-1.2.4)/1.0.2.4
In most respects, however, the potoroids are similar to small wallabies. Their hind feet are elongated, and they move by hopping, although the adaptations are not as extreme as they are in true wallabies, and, like rabbits, they often use their fore limbs to move about at slower speeds.
The potoroids are, like nearly all diprotodonts, largely herbivorous. However, while they take a wide variety of plant foods, most have a particular taste for the fruiting bodies of fungi, and often depend on fungi to see them through periods when little else is available to eat in the dry Australian bush. One example of a potoroo that sustains itself on fungi is the long-footed potoroo. This animal's diet is almost entirely made up of fungal spores. This limits its habitat range as it needs to live in a moist environment, with dense cover to reduce predation from introduced species such as foxes and feral cats.
Ecology
The once populous species of this family played a role in the engineering of soil, dominating the sub-storey of vegetation, and regarded as crucial to the maintenance of the friable soils that they created by digging for fungi and other subsoil foods.
Status
Four modern species of bettongs are extant and two have become extinct. Bettongs were endangered because settlers took much of their habitat, and the red foxes they introduced to the continent also killed many of them. At one time, several species lived all over Australia. Today, the Tasmanian bettong lives only in the eastern half of Tasmania, and the northern bettong lives only in three isolated populations in northern Queensland.
The potoroines have exemplified the impact of ecological changes since colonisation of Australia. Most species have become extinct within their former distribution range, and are either totally extinct or conserved only by preservation in isolated habitat and re-population programs.
Classification
A basal branch of the macropods, the three extant genera of the Potoroidae contain eight species.
The arrangements of the related taxa have seen an arrangement of the subfamilies within Potoroidae, although an earlier classification within the family Macropodidae has also been supported by genetic studies.
A conservative arrangement of modern and fossil taxa may be summarised as:
- family Potoroidae:
- subfamily †Palaeopotoroinae:
- genus Palaeopotorous;
- subfamily Potoroinae:
- genus Aepyprymnus;
- genus Bettongia;
- genus †Borungaboodie;
- genus †Milliyowi;
- genus †Caloprymnus;
- genus Potorous;
- genus †Purtia;
- genus †Wakiewakie;
- genus †Gumardee;
- subfamily †Bulungamayinae:
- genus Bulungamaya;
- genus Wabularoo;
- genus Wanburoo;
- genus Nowidgee;
- genus Ganguroo.
The long-nosed potoroo (Potorous tridactylus)
The long-nosed potoroo (Potorous tridactylus) is a small, hopping mammal native to forests and shrubland of southeastern Australia and Tasmania. A member of the potoroo and bettong family (Potoroidae), it lives alone and digs at night for fungi, roots, or small insects. It is also a marsupial (like kangaroos) and carries its young in a pouch. The long-nosed potoroo is threatened by habitat loss and introduced species such as cats or foxes. There are two subspecies: Potorous tridactylus tridactylus on mainland Australia, and Potorous tridactylus apicalis on Tasmania, with lighter fur.
At first glance, the long-nosed potoroo with its pointed nose and grey-brown fur looks very much like a bandicoot — that is, until it hops away with its front feet tucked into its chest, revealing its close relationship with the kangaroo family. The long-nosed potoroo exhibits many morphological specializations such as an elongated pointed rostral region (nose), erect ears, large eyes, claws for digging, and long robust hind legs. It is only a small marsupial, with a body length between 34 and 38 cm (13–15 in), and a semi-prehensile tail length of 15 to 24 cm (5.9–9.4 in).
As it is rarely seen in the wild, better indicators of its presence are the runways it makes through the undergrowth and the hollow diggings it leaves behind when feeding on underground roots and fungi.
Taxonomy
The species was first noted in 1790 by John White in a record of his journey to Botany Bay. The informal description named the animal as a "Poto Roo" or "Kangaroo Rat" and was accompanied by an illustration.
The classification of the genus Potorous has seen the name subjected to frequent revisions. The following is a summary of the associated species and subspecies:
- genus Potorous:
- Potorous gilbertii Gilbert's potoroo;
- Potorous longipes Long-footed potoroo
- Potorous platyops Broad-faced potoroo, † modern extinction;
- Potorous tridactylus Long-nosed potoroo;
- Potorous tridactylus tridactylus;
- Potorous tridactylus apicalis.
Distribution
Potorous tridactylus is considered threatened in the state of Victoria (Flora Fauna Guarantee Act 1988) and vulnerable in the state of Queensland (Nature Conservation Act 1992) and nationally (Environment Protection and Biodiversity Conservation Act 1999), although the IUCN lists it as being at minimal risk.
Potorous tridactylus inhabits dense thickets, undergrowth and can be found in the steppe. Relatively thick ground cover is an important component of Potorous tridactylus habitats. These animals inhabit forests and other woodland and shrub communities, where above-ground nests may be constructed of dry vegetation among clumps of grass, under shrubs or in low, dense thickets. Potorous tridactylus also uses a wide range of moist forest and wet habitats located on sandy loam soils where annual rainfall exceeds 760 mm. Finally, Potorous tridactylus usually stays at altitudes from sea level and up to 250 m, although it has also been found at altitudes up to 650 m.
Description
The weight of Potorous tridactylus ranges from 0.70 to 1.80 kg. In appearance and size, the Potorous tridactylus resembles a rabbit with an elongated rat-like face. The Potorous tridactylus has a head and body of 300-400 mm, and its tail measures between 150 and 260 mm. The coat of the Potorous tridactylus is smooth, soft, grey or light brown to brown on the upper body, greyish or whitish underneath, and often with a white tail tip. The central claws of its forelegs are well adapted for clawing and digging the ground: they are very long and sharp. Potorous tridactylus has a tenacious, down-curved tail, which it uses to transport collected plant materials. It has powerful hind limbs, well adapted for jumping and moving at high speed. Potorous tridactylus can hop or move conventionally on all fours. Unlike kangaroos, they have well-developed canines, with a total of 32-34 teeth.
Nutrition
Potorous tridactylus feed on the aerial parts of herbaceous plants and roots. An important part of the daily diet of Potorous tridactylus from May to June is mushrooms (more than 70%), as well as insects (especially in summer).
Reproduction
Female Potorous tridactylus have a well-developed pouch containing four nipples. These marsupials breed throughout the year, with peaks in early spring and summer. Males and females reach sexual maturity at about 12 months of age and the reproductive potential is about 2.5 offspring per year. The gestation period is about 38 days. Females give birth to a calf weighing about 300 mg. The young suckle milk in their mother's pouch for 120-170 days. Birth is usually accompanied by a period of postpartum oestrus; the embryo formed after mating goes into diapause while the existing pups remain in the mother's pouch and feed on her milk, and the embryo comes out of diapause when the older pup leaves the pouch or dies for some reason. After development resumes, the embryo is born in about 30 days. After birth, the calf climbs into the mother's pouch on its own and attaches itself to one of the four teats.
Behaviour and nutrition
Potorous tridactylus lead a nocturnal, sedentary lifestyle and rarely stray from their nest. The male site is about 47 acres and overlaps with that of several females. There is some evidence that male habitats do not overlap. Potorous tridactylus lead a solitary existence, except during mating and breeding periods. The longevity of these marsupials can reach seven years, but usually does not exceed 4-5 years.
A wide range of foods contributes to the species' ability to survive in diverse environments. This has proven invaluable and allows the Potorous tridactylus to survive fires, which destroy all available food sources except those on the ground (a situation that leads many other mammals to their doom).
Potorous tridactylus is an omnivorous animal. It obtains most of its food from small holes in the ground, which it digs with the claws of its forelegs. Berries, mushrooms, grasses, succulent stems, roots and tubers are the main source of food for the Potorous tridactylus throughout the year. Of this assemblage, mushrooms are the most frequent food, and herbs are only consumed during the winter, when general food availability is lower. Insects and their larvae make up a meagre 1-2% of its winter diet, but this may increase to 21% in summer.
