The Russian desman (Desmana moschata)
The Russian desman (Desmana moschata) is listed as "threatened" in the IUCN Red List
The Russian desman (Desmana moschata) is listed in the Red Data Book of Russia
The Russian desman (Desmana moschata) is a species of soricomorphic mammal of the family Talpidae (insectivorous order), the only one of the genus Desmana.
One of two species in the subfamily Desmaninae, sometimes identified as a family; the second species is the Pyrenean desman (Galemys pyrenaicus).
Description and characteristics of the structure
The Desmana moschata is a small animal. Its body measures between 18 and 22 cm and its tail the same length, and it weighs up to 520 g.
The tail is covered with horny scales and has stiff hairs along the upper part, which form a keel. The tail is sort of tapering at its base (the tail has the smallest diameter). The tail (in the first third of its length) is followed by a pear-shaped thickening. The glands contain specific glands (musky and odorous), the oily musk of which is squeezed out through numerous holes in the lower part of the thickening. Behind the thickening, the tail is tightly compressed at the sides.
The nose is trunk-like. Vibrissae very long; sensory hairs growing on the body. The teeth of Desmana moschata are 44.
Limbs rather short, 5 feet, hind feet larger and broader than front feet. The toes to the claws are connected by a swimming web. Claws well developed, long, weakly arched. All tarsi have a fringe of stiff, bristly hairs on the sides, which increases the swimming surface of the tarsi.
The coat of the Desmana moschata is dense, velvety, very tough, and its hairs are not arranged like those of other animals; they extend towards the top and taper towards the root. The back is greyish or dark brown, the belly is silvery grey or silvery white. The fur retains air so well that it harbours a parasite, the viviparous beetle, which is not adapted to breathing in water.
The eyes are rudimentary, the size of a pinhead. Desmana moschata is virtually blind, but has a highly developed sense of smell and touch.
The right side of the heart is thicker and more massive than that of land animals. Water is denser than air and compresses the rib cage more. To overcome this effect, the muscles of the right ventricle are reinforced with additional muscle fibres.
Taxonomy
The Russian desman is one of two surviving species of the tribe Desmanini, the other being the Pyrenean desman. Despite its outward similarity to muskrats (a rodent), the Russian desman is actually part of the mole family Talpidae in the order Eulipotyphla. Like other moles, it is functionally blind and obtains much of its sensory input from the touch-sensitive Eimer's organs at the end of its long, bilobed snout. However, the hind feet are webbed and the tail is laterally flattened -specializations for its aquatic habitat. The body is 18 to 21 cm (7.1 to 8.3 in) long while the tail is 17 to 20 cm (6.7 to 7.9 in) in length. Easily the largest species of mole, it weighs 400 to 520 g (14 to 18 oz). Decidedly rich and thick in nature, desman fur used to be highly sought after by the fur trade. Consequently, the Russian desman is now a protected species under Russian law. However, due to loss of habitat (farming), water pollution, illegal fishing nets, and the introduction of non-native species like muskrat, population levels continue to decline. In the mid-1970s, an estimated 70,000 desmans were left in the wild; by 2004, the figure was only 35,000. However, in some Russian regions, the number of desmans appears to be increasing.
Distribution
Desmana moschata is a relict species, endemic to the former USSR. In prehistoric times, it was found in Europe as far as the British Isles. Its modern natural range is fragmented and mainly restricted to the Dnepr, Volga, Don and Ural basins. It is also found in Kazakhstan; in Ukraine, Lithuania and Belarus it is rare.
Life style
Desmana moschata is semi-aquatic. The most favourable places for muskrat habitation are closed floodplain reservoirs with a water surface area of 0.1-0.5 ha and a depth of 1.3-5 m, with low but dry and steep bank areas with aquatic vegetation and the proximity of floodplain forests.
For most of the year, the animals live in burrows with one exit each. The exit opens underwater. The main part of the passage, situated above the water level, runs almost horizontally for 2.5-3 m and is provided with 2-3 extensions (chambers or rings).
During floods, the chambers are flooded and the animals abandon them and take refuge in half-flooded trees, in sediment piles or in temporary shallow burrows dug in non-flooded parts of the bank. At the bottom of a body of water, a trench between the entrances of two adjacent burrows runs through the full thickness of silt to a sandy base.
In summer, Desmana moschata lives alone, in pairs or in families, and in winter up to 12-13 animals of different sexes and ages may live in a burrow. Each animal has temporarily visited the burrows, which are located 25-30 metres apart. This is the distance Desmana moschata travels along the connecting trench during its normal stay underwater in 1 minute (although it can stay in the water column for up to 3-4 minutes).
In captivity, Desmana moschata lives up to 5 years, in the wild up to 4 years.
Nutrition
Desmana moschata requires large amounts of food. An adult mammal can ingest as much food as its weight in a day. During the summer, Desmana moschata feeds mainly on bottom-dwelling animals, including rainbow beetle larvae, leeches, gastropod molluscs, streamer larvae, etc. During the winter months, various plant foods and even small fish are added.
Reproduction
Sexual maturity of Desmana moschata reaches 10-11 months of age. During spring floods, Desmana moschata displaced from their dens mate in pairs. During the quiet days of this period, they emit peculiar sounds: the males bite loudly and the females emit soft, melodious sounds. Gestation is accompanied by fights between the males. After 45-50 days of gestation, 1-5 pups are born, blind, naked and helpless. Newborn pups weigh between 2 and 3.3 g (about half the weight of a newborn rat). The nesting chamber is shallow and the temperature is low during the winter months. The female builds a nest with wet plants collected from the bottom of a pond. Returning to the burrow after feeding, the female shakes off the water. The fur does not get wet, but a film and droplets of water may remain on its surface at near-zero temperature.
Peak births occur in late May to June and November to December. There are two litters per year. If the female is disturbed, she transports her young to another burrow, planting them on her back. The male stays with the young. At one month of age the young begin to feed on the food of the adults; at 4-5 months of age they become independent.
Conservation status
Desmana moschata is a rare endemic species, listed in the Red Data Book of Russia, category 2: declining relict species, rare. This sad state of Desmana moschata in Russia has been caused by factors such as logging of floodplain forests, pollution of water bodies inhabited by animals, drainage of floodplains, which worsens conditions for foraging and protection, construction of dams and dykes, as well as construction of reservoirs and grazing of livestock near reservoirs.
Desmana moschata and man
In the past, Desmana moschata was a valuable commercial species. Until the third quarter of the 17th century, it was collected exclusively for its musky scent. In Russia, the dried tails of Desmana moschata were used to coat linen, and later the secret of the musk glands was used in perfumery as a scent enhancer for perfumes. It was only later that Desmana moschata was harvested for its fur, which was more highly valued than that of the beaver.
