Animal Diversity Web

Ge­o­graphic Range

Aonyx cinerea is found in coastal re­gions from south­ern India to the Malay Penin­sula and south­ern China. (Nowak, 1999; Tim­mis, 1971)

• Biogeographic Regions
• oriental
  • native
• indian ocean

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. (Hooger­w­erf, 1970; Mason and Mac­don­ald, 1986; Tim­mis, 1971)

• Habitat Regions
• tropical
• saltwater or marine
• freshwater

• Aquatic Biomes
• rivers and streams
• coastal

• Other Habitat Features
• 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. (Mason and Mac­don­ald, 1986; Tim­mis, 1971)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike

• Range mass

  2.7 to 5.4 kg

  5.95 to 11.89 lb

• Range length

  406 to 635 mm

  15.98 to 25.00 in

Re­pro­duc­tion

Asian claw­less ot­ters form monog­a­mous pairs for life. (Lan­caster, 1975; Leslie, 1970)

• Mating System
• 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. (Lan­caster, 1975; Leslie, 1970)

• Key Reproductive Features
• iteroparous
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• Breeding interval

  Aonyx cinerea may produce two litters annually.

• Breeding season

  Mating may occur throughout the year.

• Average number of offspring

  2

• Average gestation period

  60 days

• Average weaning age

  80 days

Males as­sist with nest build­ing be­fore birth and food pro­cure­ment after par­tu­ri­tion. (Lan­caster, 1975; Leslie, 1970)

• Parental Investment
• male parental care
• female parental care

Lifes­pan/Longevity

A cap­tive spec­i­men of A. cinereus lived about 16 years. (Nowak, 1999)

• Range lifespan
  Status: captivity

  16 (high) 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. (Hooger­w­erf, 1970; Med­way, 1969; Tim­mis, 1971)

• 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. (Tim­mis, 1971)

• Communication Channels
• visual
• tactile
• acoustic
• chemical

• Perception Channels
• visual
• tactile
• acoustic
• 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. (Tim­mis, 1971)

• Primary Diet
• carnivore
  • eats non-insect arthropods
  • 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

Aonyx cinerea con­sume small crabs which are con­sid­ered agri­cul­tural pests. (Mason and Mac­don­ald, 1986)

• Positive Impacts
• controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Rice farm­ers com­plain about Asian claw­less ot­ters up­root­ing plants in the pad­dies. (Mason and Mac­don­ald, 1986)

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. (Lankard, 2001)

• IUCN Red List

  Vulnerable
  More information

• IUCN Red List

  Vulnerable
  More information

• US Federal List

  No special status

• CITES

  No special status

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.