By David Hamman
Geographic Range
Aonyx cinerea is found in coastal regions from southern India to the Malay Peninsula and southern China. ()
Habitat
Aonyx cinerea individuals are commonly seen in the shallows of freshwater streams and rivers as well as coastal regions. There is often dense foliage nearby, which they use as defensive cover, and which restricts behavioral studies in the wild. Nesting burrows are dug into the muddy banks where they live. They have also been seen numerous times in rice paddies. ()
These animals are found in the following types of habitat:
tropical 
; saltwater or marine ; freshwater .
Aquatic Biomes:
rivers and streams; coastal .
Other:
riparian .
Physical Description
(5.94 to 11.88 lbs)
(15.98 to 25 in)
Aonyx cinerea weigh 2.7 to 5.4 kg, have a combined head and body length of 406 to 635 mm, and a tail length of 246 to 304 mm. They have dark, greyish-brown fur over most of their body, and a lighter cream coloration on their face and neck. Their claws are extremely reduced, and rarely extend past the digit. The paws are only partially webbed, which allows for more dexterity than otters with full webbing. ()
Some key physical features:
endothermic ; homoiothermic; bilateral symmetry .
Sexual dimorphism: sexes alike.
Reproduction
Mating may occur throughout the year.
Asian clawless otters form monogamous pairs for life. ()
Mating systems:
monogamous .
The estrous cycle is 28 days with a 3 day period of estrus. Mated pairs can have two litters of 1 to 6 young (usually 1 or 2) per year. Gestation is approximately 60 days, and newborn young are relatively undeveloped. At birth, they weigh around 50 g and have closed eyes. Eyes open at around 40 days, and pups can be seen outside the den after ten weeks. Young begin eating solid food after 80 days, and start swimming after three months. ()
Key reproductive features:
iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous .
Males assist with nest building before birth and food procurement after parturition. ()
Parental investment:
male parental care ; female parental care .
Lifespan/Longevity
A captive specimen of A. cinerea lived about 16 years. ()
Behavior
Aonyx cinerea live in extended family groups of approximately twelve individuals. They are social and vocal animals. They are often seen playing on mud banks and in the water, and slides are quite obvious in regions where they either frequently visit or permanently live. In captivity they are often seen juggling pebbles and other small objects. They are mainly active during the day. ()
Key behaviors:
natatorial ; diurnal ; motile ; sedentary ; social .
Communication and Perception
Twelve different vocalizations have been identified in this species, not counting simple alarm vocalizations. Communication also occurs with visual, chemical, and tactile cues such as social grooming, hormonal changes, and posturing. ()
Food Habits
Unlike most otters, A. cinerea individuals 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 sand and mud at the shoreline for various types of shellfish (clams and mussels) and crabs. To get at the meat they can either crush the shell manually or let heat from the sun open the shells. Their teeth are broad and robust, well-suited for crushing shells. ()
Primary Diet:
carnivore (eats non-insect arthropods, molluscivore ).
Animal Foods:
amphibians; fish; terrestrial non-insect arthropods; mollusks.
Predation
Predation on A. cinerea has not been described but it is likely that they are taken by large, primarily aquatic predators, such as crocodiles and snakes. Their amazing agility in the water may help them to avoid predation.
Ecosystem Roles
The role of A. cinerea in the ecosystem is not well understood. They impact the populations of shellfish and crustaceans in their area.
Economic Importance for Humans: Negative
Rice farmers complain about Asian clawless otters uprooting plants in the paddies. ()
Economic Importance for Humans: Positive
Aonyx cinerea consume small crabs which are considered agricultural pests. ()
Ways that people benefit from these animals:
controls pest population.
Conservation Status
IUCN Red List: [link]:
Near Threatened.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
Clawless otters are managed under the Species Survival Program. While not endangered themselves, they are being used as a model for the management of other otter species. ()
Contributors
David Hamman (author), Michigan State University.
Barbara Lundrigan (editor), Michigan State University.
