Oriental Small-clawed Otter
Encyclopedia
The oriental small-clawed otter (Aonyx cinerea), also known as Asian small-clawed otter, is the smallest otter
species in the world, weighing less than 5 kg. It lives in mangrove
swamp
s and freshwater
wetlands of Bangladesh
, Burma, India
, southern China
, Taiwan
, Laos
, Malaysia, Indonesia
, the Philippines
, Thailand
and Vietnam
. This otter is distinctive for its forepaws, as the claw
s do not extend above the fleshy end pads of its toes and fingers. These attributes give it a high degree of manual dexterity in using its paws to feed on molluscs, crab
s and other small aquatic animal
s.
The oriental small-clawed otter lives in extended family groups with only the alpha pair breeding and previous offspring helping to raise the young. Due to ongoing habitat loss, pollution
and hunting
in some areas, the oriental small-clawed otter is evaluated as vulnerable
on the IUCN Red List
of Threatened Species.
after mitochondrial DNA analysis. Another synonym
for the oriental small-clawed otter is Aonyx cinereus.
covers most of the dorsal
surface with a lighter cream coloration on the ventral surface, especially on their face and neck. The fur has relatively short hairs less than 2.5 cm in length, and it is fine, dense and velvety. Otters have two types of fur: long, stout guard hair
s and a short, fine undercoat.
Oriental small-clawed otters have flattened heads and short, thick necks; eyes are located toward the front of the head. Their ears are small and rounded, and a valve-like structure enables closure when swimming underwater. Nose pads are dusky or pinkish in color. They have vibrissae
(whiskers) on their muzzle. The vibrissae are sensitive to touch and to underwater vibrations, and are important in detecting the movements of prey.
Similar to other otters, oriental small-clawed otters have relatively short legs, which are used to swim, walk, groom and manipulate prey. Feet are very narrow and only webbed to the last joint — not all the way to the end of the toe. Thus, they have only partially webbed paws, which distinguishes them from all other otters. These partially webbed paws give them an excellent sense of touch and coordination, providing them with more dexterity than other otters with full webbing. Unlike other otters, they catch their prey in their paws instead of with their mouth. Their small, blunt, peg-like claw
s are extremely reduced and rarely extend past the digit.
The oriental small-clawed otter's tail
is long, about one-third of total body length. The tail is thick at the base, muscular, flexible, and taper to a point. Subcutaneous and scent glands are located at the base of the tail. The tail is used for propulsion when swimming at high speed, to steer when swimming slowly and for balance when standing upright on hind legs.
' Species Survival Plan
, SeaWorld
breeds this species to preserve it in zoos and aquariums.
One of the biggest, if not the biggest, oriental small-clawed otter exhibit is at Zoo Basel
. There, the otter's outdoor exhibit is about 2'000 square meter (21'528 square feet) big and has two rivers, four ponds, and over a dozen tunnels. Only one pair of otters is living on the exhibit, but shares it with Indian Rhinoceros
es and Muntjac
s.
Oriental short clawed Otters have been hand-reared and kept by private individuals.
Otter
The Otters are twelve species of semi-aquatic mammals which feed on fish and shellfish, and also other invertebrates, amphibians, birds and small mammals....
species in the world, weighing less than 5 kg. It lives in mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
swamp
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...
s and freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
wetlands of Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...
, Burma, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, southern China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, Laos
Laos
Laos Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ Sathalanalat Paxathipatai Paxaxon Lao, officially the Lao People's Democratic Republic, is a landlocked country in Southeast Asia, bordered by Burma and China to the northwest, Vietnam to the east, Cambodia to the south and Thailand to the west...
, Malaysia, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
and Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
. This otter is distinctive for its forepaws, as the claw
Claw
A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...
s do not extend above the fleshy end pads of its toes and fingers. These attributes give it a high degree of manual dexterity in using its paws to feed on molluscs, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s and other small aquatic animal
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
s.
The oriental small-clawed otter lives in extended family groups with only the alpha pair breeding and previous offspring helping to raise the young. Due to ongoing habitat loss, pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
and hunting
Hunting
Hunting is the practice of pursuing any living thing, usually wildlife, for food, recreation, or trade. In present-day use, the term refers to lawful hunting, as distinguished from poaching, which is the killing, trapping or capture of the hunted species contrary to applicable law...
in some areas, the oriental small-clawed otter is evaluated as vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
of Threatened Species.
History
This species was formerly thought to be the only member of the genus Amblonyx; however, it has recently been confirmed as AonyxAonyx
Aonyx is a genus of otters, containing two species, the African Clawless Otter and the Oriental Small-clawed Otter. The word 'Aonyx' means 'clawless', derived from the prefix 'a-' and .-Species and subspecies:...
after mitochondrial DNA analysis. Another synonym
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
for the oriental small-clawed otter is Aonyx cinereus.
Morphology
Oriental small-clawed otters are the smallest of all otters in the world. The overall length can range from 70 to 100 cm (28–39 in), about 30 cm (12 in) of which is comprised by the tail. Weight can range from 1 to 5.4 kg (2.2-11.9 lbs). Their body shape is typically slender, streamlined and serpentine, and its flexibility allows grooming of almost all their fur. Dark, grayish-brown furFur
Fur is a synonym for hair, used more in reference to non-human animals, usually mammals; particularly those with extensives body hair coverage. The term is sometimes used to refer to the body hair of an animal as a complete coat, also known as the "pelage". Fur is also used to refer to animal...
covers most of the dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
surface with a lighter cream coloration on the ventral surface, especially on their face and neck. The fur has relatively short hairs less than 2.5 cm in length, and it is fine, dense and velvety. Otters have two types of fur: long, stout guard hair
Guard hair
Guard hairs are the longest, coarsest hairs in a mammal's coat, forming the topcoat . They taper to a point and protect the undercoat from the elements. They are often water repellent and stick out above the rest of the coat...
s and a short, fine undercoat.
Oriental small-clawed otters have flattened heads and short, thick necks; eyes are located toward the front of the head. Their ears are small and rounded, and a valve-like structure enables closure when swimming underwater. Nose pads are dusky or pinkish in color. They have vibrissae
Vibrissae
Vibrissae , or whiskers, are specialized hairs usually employed for tactile sensation. The term may also refer to the thick hairs found inside human nostrils, but these have no sensorial function and only operate as an airborne particulate barrier...
(whiskers) on their muzzle. The vibrissae are sensitive to touch and to underwater vibrations, and are important in detecting the movements of prey.
Similar to other otters, oriental small-clawed otters have relatively short legs, which are used to swim, walk, groom and manipulate prey. Feet are very narrow and only webbed to the last joint — not all the way to the end of the toe. Thus, they have only partially webbed paws, which distinguishes them from all other otters. These partially webbed paws give them an excellent sense of touch and coordination, providing them with more dexterity than other otters with full webbing. Unlike other otters, they catch their prey in their paws instead of with their mouth. Their small, blunt, peg-like claw
Claw
A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...
s are extremely reduced and rarely extend past the digit.
The oriental small-clawed otter's tail
Tail
The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds...
is long, about one-third of total body length. The tail is thick at the base, muscular, flexible, and taper to a point. Subcutaneous and scent glands are located at the base of the tail. The tail is used for propulsion when swimming at high speed, to steer when swimming slowly and for balance when standing upright on hind legs.
Distribution
This species could be found distributed in coastal regions from Southern India to South China, South-east Asia, Sumatra, Java, and Palawan. It is known from all regions of Sabah and Sarawak, Brunei, and in Central of Kalimantan. It could be found in almost all other parts of Borneo.Habitat
They commonly could be found in freshwater wetland systems such as freshwater swamps, meandering rivers, mangroves and tidal pools. They also dominated irrigated rice fields and wandering in area between patches of reeds and river debris where many crab species (Brachyura) were more likely to be found. They dislike bare and open areas that do not offer any shelter. Thus, they prefer pond areas and rice fields more than the rivers. However, in the riverine systems they would only chose the area with low vegetation. Their nesting burrows dug into the muddy banks where they live. This species spend most of their time on land unlike any other otters.Reproduction
The oriental Small-clawed otter form monogamous pairs for life. The estrous cycle in the female is 28 days with 3 days period of estrus. The mated pairs can have two litters of 1 to 6 young per year. Their gestation period is about 60 days. The newborn are relatively undeveloped. When they are born, they weigh around 50 g, are toothless, practically immobile and their eyes are still closed. They remain in their birthing dens and spend their first few weeks nursing and sleeping. The pups nurse every 3 to 4 hours for 10 to 15 minutes at a time. They are fully weaned at 14 weeks. The newborn will only open their eyes after 40 days. In the next 40 days, the young can start to eat solid food and can swim three months later. All the young otter will stay with their mother until the next litter is born. The male otter assists the female building the nest before birth and in food procurement after parturition. Life span of this species is around 11 years to 16 years.Behavior
They are diurnal animals. They are very active during daytime in remote areas which are free of human disturbance. They continually groom their fur to maintain their insulating qualities. They spend most of their time grooming and usually could be seen on land grooming and drying their fur. They dry themselves by rolling on the ground or rubbing against logs or vegetation. They are excellent swimmers too. They swim by moving their hind legs and tail. They ‘dog-paddle’ with all four feet while swimming or floating. When swimming at a high speed, they undulates the entire body including their tail up and down while their hind feet steer. They can dive under water for about 6 to 8 minutes. They produce small amounts of feces which are well-known as spraint by otter researchers. The spraints are one of important way for communication among the otters. Other otter could indicate the presence of other individual based on the olfactory and visual of the spraints. Generally, they sleep and resting on land either above ground or in the dens. They often sleep in areas with moderate disturbance. Oriental small-clawed otters are most social animals. They live in extended family groups of about 12 individuals. They are often seen playing and sliding on muddy banks and in the water in regions where they frequently visit or live. They defend their territories by working, scratching and occasionally fighting.Communication
There are few ways for this species to communicate such as vocalizations, scent markings and sign heaps. They often produce sounds and communicate vocally. This species has at least 12 different types of vocalization. Meanwhile, scent is the most important sense for communication especially for marking territorial boundaries. Their tail has scent glands where they deposit their musky scent on their spraint. The spraint is deposited either in tree trunks, boulders, trails and pool edges. Finally, they also have signed heaps which is visual indicator of an otter’s presence. The sign heaps is small mounds of sand, gravel, grass or mud scraped up by the otters. Besides that, their communication also occurs with chemical and tactile cues such as social grooming, hormonal changes and posturing.Diet and eating habits
Oriental Small-clawed otter feed mainly on invertebrates such as crab and other crustaceans, molluscs and amphibians. This is proved from the evident of the last two upper teeth (pm4 and m3) which are larger in size for crushing the exoskeleton of crabs and other hard shelled prey. They also feed on insects and small fish such as gouramis and catfish. They supplement their diet with rodents, snakes and frogs too. Apart from crabs, the major prey items for them are the mudskipper (Gobioidei). Only the relatively rare dietary component of rodents, snails and snakehead fish (Clarius spp.) showed no significant difference among seasons. They hunt food by using their vibrissae to detect movements of prey in the water. They use their forepaws to locate and capture items rather than their mouth. Their incomplete webbing gives them a great deal of manual dexterity. They dig in sands and mud for shellfish such as clams and mussels and crabs as well. To get at the meat they crush the shell manually or let heat from the sun open the shells. Therefore, there teeth are broad and robust very suitable for crushing shells.Economic importance for humans
They consume small crabs which are considered as agricultural pests. However, they may uproot plants in the paddy fields. Thus, they benefit as pest population controller for the farmer.Ecosystem roles
They influence the population of shellfish and crustaceans and crabs in their living area.Conservation status
They are seriously threatened by rapid habitat destruction, hunting and pollution. Their population trend is decreasing. Nevertheless, they are a protected species. They are managed under Species Survival Program. In this program, they were used as a model for the management of other otter species while not endangered themselves.In captivity
As part of the Association of Zoos and AquariumsAssociation of Zoos and Aquariums
The Association of Zoos and Aquariums was founded in 1924 and is a nonprofit organization dedicated to the advancement of zoos and public aquariums in the areas of conservation, education, science, and recreation.The AZA headquarters is located in Silver...
' Species Survival Plan
Species Survival Plan
The American Species Survival Plan or SSP program was developed in 1981 by the Association of Zoos and Aquariums to help ensure the survival of selected species in zoos and aquariums, most of which are threatened or endangered in the wild....
, SeaWorld
SeaWorld
SeaWorld is a United States chain of marine mammal parks, oceanariums, and animal theme parks owned by SeaWorld Parks & Entertainment. The parks feature captive orca, sea lion, and dolphin shows and zoological displays featuring various other marine animals. There are operations in Orlando,...
breeds this species to preserve it in zoos and aquariums.
One of the biggest, if not the biggest, oriental small-clawed otter exhibit is at Zoo Basel
Zoo Basel
Zoo Basel is a non-profit zoo located within the city of Basel, Switzerland. Its official name is Zoologischer Garten Basel — or in English: Basel Zoological Garden. Basel residents, however, call their zoo affectionately Zolli...
. There, the otter's outdoor exhibit is about 2'000 square meter (21'528 square feet) big and has two rivers, four ponds, and over a dozen tunnels. Only one pair of otters is living on the exhibit, but shares it with Indian Rhinoceros
Indian Rhinoceros
The Indian Rhinoceros is also called Greater One-horned Rhinoceros and Asian One-horned Rhinoceros and belongs to the Rhinocerotidae family...
es and Muntjac
Muntjac
Muntjac, also known as Barking Deer and Mastreani Deer, are small deer of the genus Muntiacus. Muntjac are the oldest known deer, appearing 15–35 million years ago, with remains found in Miocene deposits in France, Germany and Poland....
s.
Oriental short clawed Otters have been hand-reared and kept by private individuals.