Overview

Distribution

Range Description

Central Rainforest Zone and peripheral areas from Nigeria (Cross River) eastwards through Cameroon, Equatorial Guinea, Gabon, Central African Republic, Chad, Republic of Congo, Sudan, Democratic Republic of Congo, to western Uganda and western Kenya and Tanzania, and southwards to central Angola and northern Zambia (Corbet 1974). From sea level up to 1,800 m. Occurs in the preserved rainforest of Kakamega, Kenya.
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Geographic Range

Potamogale velox is found only in central Africa, from the southern regions of Nigeria, Gabon, and The Central African Republic to the Northern regions of Angolia and Zambia. It is rarely found west of Tanzania and Uganda. One small population lives between Uganda and Kenya (African Mammal Databank).

Biogeographic Regions: ethiopian (Native )

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Physical Description

Morphology

Physical Description

The Giant Otter Shrew got its common name because of its physical resemblance to otters. It has a broad, flat muzzle covered with stiff whiskers, and flaps of skin that seal its nostrils when diving. It has small eyes and external ears. The thick round body is covered with a dense undercoat and course guard hairs. P. velox has a dark brown back and whitish under parts. The tail is covered with a short, silky coat of fur. It is compressed laterally, and allows P. velox to swim with a fish-like motion (Knigdon, 1997; Nicoll, 1985; Walker, 1983). Legs, which are short and lack webbed digits, are not used for swimming. The hind feet have a flap if skin along the inside that allows them to be held snugly against the body when swimming. There are also two syndactylous toes on the hind feet, used for grooming. On land P. velox is plantigrade (Walker, 1983; Nicoll, 1985). Females have two mammae on the lower abdomen (Nicoll, 1985).

Range mass: 300 to 950 g.

Range length: 535 to 640 mm.

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
Found in streams in equatorial rain forests. Lives along rather small slow-flowing forest streams, forest pools and mountain torrents (from an altitudinal range of 0–1,800 m) where banks provide habitats for nest chambers (Nicoll and Rathbun 1990). Also along streams, bordered by gallery forest. Normally does not occur in large rivers, although one was found in the Ivindo river (Gabon) where it was several hundred metres wide. This species is an adept swimmer that feeds on crabs, fish and amphibians. It lives in riverbank burrows, which have an entrance below the water level. It shelters in its burrows during the day becoming active in the afternoon. It is possibly a solitary species with each adult occupying between 500–1,000 m of stream.

Very muscular tail enables efficient swimming by horizontal undulations (Kingdon 1974) as in fishes and crocodiles. This method of swimming is unique amongst aquatic mammals (e.g., seals arid whales) which usually swim by undulations in a vertical plane. Forelimbs not used for propulsion. Moving on land is rather clumsy. Body pelage groomed with comb-like structure formed by the fusion of second and third toes. Nocturnal with several bouts of activity each night (Dubost 1965, Nicoll 1985); rests during daytime in burrow in river bank. When disturbed, escapes in the water. Movements over long distances always by water, never over-land.

Foraging and food Forages in water, feeding only on aquatic prey. Hunts by dives, each lasting for only several seconds. Prey located using the sensitive vibrissae and odor; eyes apparently not used to locate I prey. Analysis of stomach contents and feces show that diet is mainly fishes, crabs, shrimps, and water insects; frogs rarely eaten (Dubost 1965). In captivity eats 15– 20 crabs per night (Durrell 1953).

Latrines probably used to mark boundaries of territory (Dubost 1965). The den, with the nest chamber, is entered from below or above water level and is usually placed under a tree.

Breeds during wet and dry seasons. One (n=3) or two (n=2) pups/litter. Probably two litters/year (Dubost 1965).

Systems
  • Terrestrial
  • Freshwater
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P. velox prefers aquatic environments in the central African rain forest. Its preferred habitats include both high and low order streams, swamps, and during the rainy season some animals may migrate to small forest pools (Kingdon, 1997; Walker 1983).

Range elevation: 0 to 1800 m.

Habitat Regions: freshwater

Terrestrial Biomes: rainforest

Aquatic Biomes: rivers and streams

Wetlands: swamp

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Trophic Strategy

Food Habits

P. velox is a nocturnal predator, hunting primarily by touch and scent in calm pools. It searches both the pool and the bank for food. It prefers areas that have cover to retreat to when it feels threatened (Nicoll, 1985). P. velox attacks prey using sharp bites, sometimes pinning the prey with its fore feet, and flipping crabs over to attack their ventral surface. When attacking larger prey P. velox hisses, and avoids crabs larger than 7 cm across (Nicoll, 1985; Walker, 1983). The prey preference varies among individuals; some prefer crabs; others, frogs, or even fish. Frogs are eaten headfirst and fish are pulled into manageable bits. Prey is consumed on the bank (Nicoll, 1985). They also eat insects, mollusks, and prawns.

Animal Foods: amphibians; fish; insects; terrestrial non-insect arthropods; mollusks

Primary Diet: carnivore (Eats terrestrial vertebrates, Piscivore , Insectivore , Eats non-insect arthropods, Molluscivore )

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Associations

Known prey organisms

Potamogale velox preys on:
non-insect arthropods
Actinopterygii
Mollusca
Arthropoda
Insecta
Amphibia

This list may not be complete but is based on published studies.
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Life History and Behavior

Life Expectancy

Lifespan/Longevity

Little in known about the longevity of P. velox, but when held in captivity individuals quickly deteriorate (Nicoll, 1985).

Range lifespan

Status: captivity:
1 to 14 days.

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Reproduction

Males move long distances in search of mates and it is thought that males rut during the wet season (Nicoll, 1985).

Little is known about the reproductive patterns of P. velox, but females examined were generally developing twins (Nicoll, 1985).

Breeding season: Wet season

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal )

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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Vogel, P. (IUCN SSC Afrotheria Specialist Group)

Reviewer/s
Rathbun, G. (Afrotheria Red List Authority) & Hoffmann, M. (Global Mammal Assessment Team)

Contributor/s

Justification
The species is not thought to be declining at a rate significant enough to qualify for a higher category, and is listed as Least Concern. The current population seems to be declining, but is not well known. In Cameroon (and probably elsewhere) forest clearance and soil erosion cause murkiness and opaqueness of the water in forest streams, and resulted in disappearance of local population of these otter-shrews (Nicoll 1985).

History
  • 2006
    Least Concern
    (IUCN 2006)
  • 2006
    Least Concern
  • 1996
    Endangered
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The habitat of P. velox is highly fragmented (Walker, 1983; African Mammal Databank; Nicoll, 1985). While they can tolerate seasonally cloudy streams, streams muddied from erosion and deforestation are little used (Walker, 1983; African Mammal Databank). Habitat quality is apparently important to this species. Some drown in fishing nets or fish traps (Walker, 1983; Kingdon, 1997), and members of this species have not survived well in captivity (Nicoll, 1985). There is ongoing research about the effects of human activity on them (African Mammal Databank).

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

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Population

Population
Mean density in good habitats may be 1 territorial animal /0.5 to 1 km length of stream with maximum densities of about 1 per 100 m river (Dubost 1965).

Population Trend
Decreasing
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Threats

Major Threats
Soil erosion caused by deforestation increases the opaqueness of waterways to the detriment of this species. This is a particular problem in Cameroon (Nicoll 1985), but a potential threat in the other range states undergoing rapid forest loss. If forest strips lining the banks of the inhabited waterways remain intact then viable population are thought to be maintained. This species is also widely hunted for its skin and is accidentally trapped (but the extent to which this last is a threat to survival is unknown).
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Management

Conservation Actions

Conservation Actions
Occurs in a number of protected areas across its range. Basic biology and conservation research will determinre the types and feasibility of realistic conservation measures.
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Wikipedia

Giant otter shrew

The giant otter shrew (Potamogale velox) is a semiaquatic, carnivorous tenrec. It is found in the main rainforest block of central Africa from Nigeria to Zambia, with a few isolated populations in Kenya and Uganda. It is found in streams, wetlands and slow flowing larger rivers.[2] It is monotypic in the genus Potamogale.

Contrary to its name the giant otter shrew is not a true shrew (Soricidae) but a tenrec (Tenrecidae). The common name refers to their resemblance to otters with their flat face and stiff whiskers, and the tenrecs' overall superficial similarity to true shrews. They are nocturnal carnivores that feed on aquatic animals.

Description[edit]

The giant otter shrew is a mammal superficially similar to an otter in appearance. It is characterized by a long, flat tail, which it uses for swimming by sideways undulation like a fish. It has a muzzle covered with bristles, and flat shielded nostrils. It has dense, soft hair, silky on the tail.[2]

It has small eyes and external ears. Its fur consists of a dense undercoat and coarse guard hairs. It possesses counter-shading with dark brown on its back and whitish or yellowish under parts.[3] The tail is covered with a short, silky coat of fur and is compressed laterally which allow it to swim by horizontal undulations as in fishes and crocodiles.[1] Its legs are short and lack webbing so they are not used for swimming. The hind feet have a flap of skin along the inside that allows them to be held snugly against the body when swimming.[3] There are also two syndactylous (2nd and 3rd toes are fused) toes on the hind feet, used for grooming. On land P. velox is plantigrade.[3] Females have two mammae on the lower abdomen [3] for feeding young.

The mass ranges from 300 to 950 g. Head and body length is 290–350 mm, and reaches 535–640 mm with tail.

Geographic range[edit]

Giant otter shrews are native to central Africa, from the southern regions of Nigeria (central Rainforest Zone),and then eastward through Equatorial Guinea, Gabon, and the Central African Republic, Chad, the Republic of Congo, the Democratic Republic of the Congo, Sudan to the northern regions of Angola and Zambia. There is a small population that lives between Uganda and Kenya and preserved rainforest of Kakamega, Kenya.[3][1]

Habitat[edit]

This species prefers fresh water aquatic microhabitats in the rainforest. Preferred environments include fast flowing rivers, streams, swamps, coastal rivers,[4] and during rainy season some may retreat to small forest pools (altitude range from 0–1,800m).[3] River banks provide good habitats for breeding and nesting. These animals make burrows with an entrance below water level (like otters) and during the day find shelter there and then become active in the afternoon.[4]

Behavior[edit]

The giant otter shrew builds burrows among riverbank crevices.[2] It chooses dry leaves with which to line its nest. This is also where breeding takes place.[3] The burrows are frequently changed. When foraging, otter shrews take frequent grooming breaks.[3] When traveling upstream the otter shrew travels on the bank and then swims downstream. The night foraging routine is regular and predictable, and covers up to 800 meters a night. P. velox regularly visited discrete piles of feces that were sheltered and probably used to mark boundaries of territory.[3]

Giant otter shrews are solitary with one shrew occupying between 500–1,000 m of stream.[1]

Food habits[edit]

P. velox is a nocturnal predator, hunting primarily by touch and scent in and around calm pools.[3] Each dive lasts only seconds.[1] P. velox searches both within the pool and along the bank for prey[3] using the sensitive vibrissae and odor and apparently not eyesight.[5] It prefers areas that have cover to retreat to when it feels threatened.[1] P. velox attacks prey using sharp bites, sometimes pinning the prey with its fore feet, and flipping crabs over to attack their weaker ventral surface. They usually avoid crabs larger than 7 cm across.[3] The prey preference varies among individuals; some prefer crabs; others, frogs or fish. Frogs are eaten headfirst and fish are pulled apart into manageable bits. Prey is consumed on the bank. P. velox also eats insects, mollusks, and freshwater prawns.[3] In captivity it eats 15–20 crabs per night.[1]

Lifespan[edit]

Giant otter shrews fare very poorly in captivity. Captive specimens have been recorded to deteriorate in health very quickly, living only 1– 14 days.[3]

Reproduction[edit]

Giant otter shrews breed during the wet/rainy season. They reproduce sexually and give birth to one or two pup per litter, once or twice a year. Males move long distances via water in search of mates and it is thought that males rut (or fight) during the wet season.[3]

Conservation status[edit]

Currently this species is of least concern because its declining rate is not significant enough to move to the next category.[1] However it is on the decline. One of the major threats to this species is the soil erosion caused by deforestation especially in Cameroon.[1] While they can tolerate seasonally cloudy streams, streams muddied from erosion and deforestation are little used.[3] Some drown in fishing nets or fish traps,[3] and members of this species have not survived well in captivity. There is ongoing research about the effects of human activity on them. It is also hunted extensively for its skin.[1]

References[edit]

  1. ^ a b c d e f g h i j Vogel, P. (Afrotheria Specialist Group) (2008). Potamogale velox. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 29 December 2008.
  2. ^ a b c Kingdon, Jonathan (1997). The Kingdon Field Guide to African Mammals. San Diego: AP Natural World. p. 137. ISBN 0-12-408355-2. 
  3. ^ a b c d e f g h i j k l m n o p q Tamaska, Gabriel. (2001-10-05) ADW: Potamogale velox. Animaldiversity.ummz.umich.edu. Retrieved on 2013-01-11.
  4. ^ a b Potamogale velox, fieldmuseum.org
  5. ^ Bronner, G. N.; Jenkins, P. D. (2005). "Order Afrosoricida". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. p. 76. ISBN 978-0-8018-8221-0. OCLC 62265494. 
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