Aonyx cinerea

Geographic Range

Amblonyx cinereus is found in coastal regions from southern India to the Malay Peninsula and southern China.

• Biogeographic Regions
• oriental oriental
  • native native
• indian ocean

Habitat

Amblonyx cinereus 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.

• Habitat Regions
• tropical tropical
• saltwater or marine saltwater or marine
• freshwater freshwater

• Aquatic Biomes
• rivers and streams
• coastal coastal

• Other Habitat Features
• riparian riparian

Physical Description

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

Asian clawless otters form monogamous pairs for life.

• Mating System
• monogamous 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 iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Males assist with nest building before birth and food procurement after parturition.

• Parental Investment
• male parental care male parental care
• female parental care female parental care

Lifespan/Longevity

A captive specimen of A. cinereus lived about 16 years.

Behavior

Amblonyx cinereus 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 natatorial
• diurnal diurnal
• motile motile
• sedentary sedentary
• social 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.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

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 carnivore
  • eats non-insect arthropods
  • molluscivore molluscivore

• Animal Foods
• amphibians
• fish
• terrestrial non-insect arthropods
• mollusks

Predation

Predation on A. cinereus 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. cinereus in the ecosystem is not well understood. They impact the populations of shellfish and crustaceans in their area.

Economic Importance for Humans: Positive

Amblonyx cinereus consume small crabs which are considered agricultural pests.

• Positive Impacts
• controls pest population

Economic Importance for Humans: Negative

Rice farmers complain about Asian clawless otters uprooting plants in the paddies.

Conservation 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.

Additional Links

Encyclopedia of Life

Contributors

David Hamman (author), Michigan State University, Barbara Lundrigan (editor), Michigan State University.

References

Hoogerwerf, A. 1970. Udjung Kulon . Leiden: E. J. Brill.

Lancaster, W. 1975. Exhibiting and breeding the asian small-clawed otter at Adelaide Zoo. International Zoo Yearbook , 15: 63-65.

Lankard, J. 2001. AZA annual report on conservation and science 1999-2000. Volume I: Conservation programs reports . Silver Springs, MD: American Zoo and Aquarium Association..

Leslie, G. 1970. Observations on Oriental short-clawed otter at Aberdeen Zoo. International Zoo Yearbook , 10: 79-81.

Mason, C., S. Macdonald. 1986. Otters: ecology and conservation . Cambridge University Press.

Medway, L. 1969. The wild mammals of Malaya . Kuala Lampur: Oxford University Press.

Nowak, R. 1999. Walker's Mammals of the World, Volume 1 . Baltimore and London: The Johns Hopkin University Press.

Timmis, W. 1971. Observations on breeding the Oriental short-clawed otter, *Amblonyx cinerea*, at Chester Zoo. International Zoo Yearbook , 11: 109-111.