Yapok (Water Opossum)

## About

A yapok in a wetland.

The Yapok ***(Chironectes minimus)*** also commonly known as the water opossum, is a species of opossum, native to the Americas. Yapoks are medium to small sized mammals with slender bodies and long limbs. They have greyish tan coats, which are mottled with large dark greyish brown bands and spots, particularly across their back, over their eyes and down their limbs. The underbelly is a stark white, also appearing on the yapok's cheeks, chin and inner-legs. The coat overall is waterproof and aids in buoyancy. The tail is bare and mostly grey-pink or black in colour. its end is tipped with cream or white. The yapok's tail is almost as long as its body, ranging from 30-43cm (12-17in). It is possible that the tail used to manipulate or carry objects however, its main purpose is acting as a rudder while the yapok swims. One of the most characteristic features of the yapok is its odd forefeet. They are long-fingered and clawed, used to catch prey rather than paddle. In contrast, the broad hindfeet are heavily webbed and spade-shaped. They greatly aid the yapok while swimming, acting as paddles. Both feet are hairless and pale pink in colour. The yapok's snout is narrow and its head is round, topped with two small, naked, triangular ears. Across its face are many sensory bristles and whiskers, which help the yapok detect potential prey and predators, as well as allowing it to sense movements in the water. As a nocturnal species, the yapoks eyes are large, round and well-developed, being able to see in low-light environments. Though the yapok is often called the water opossum in English, the name yapok is more widely used to describe the animal across its range. It is likely that the name originates from the name of the Oyapok river of French Guiana. Yapok can grow to a length of 27-40cm (11-16in) and can weigh up to 604-790g (21-28oz) however, males are typically larger on average.

## Diet

The yapok is a omnivorous hunter that preys upon freshwater organisms. its diet is mostly comprised of crustaceans however, aquatic insects, larvae and frogs are also commonly eaten. When eating crustaceans, the yapok will position the prey on its abdomen, cracking and tearing its exoskeleton in order to get to the meat. In order to maintain its waterproof coat, the yapok consumes various oil-producing prey items. It is also common for yapoks to eat fruits and aquatic plants. They eat plant matter exclusively when other food sources are unavailable or scarce. When eating, the yapok will stand on its hind legs and use its large hands to lift the food into its mouth, where it will rip it apart with its sharp teeth. As briefly mentioned previously, the yapok uses its large forefeet -or hands-, as a method of grabbing aquatic animals, rather than swimming tools.

## Conservation Status

While the yapok is classed as least concern, some factors still threaten the species. Many authors report that yapoks cannot survive in areas were foliage dense waterways are absent. If these claims are true, then the degradation of their habitat would be the largest of these threats however, many others contradict these reports, sighting yapoks in agricultural areas. General water quality is also a feature of prime yapok habitat and if water is degraded in areas of its range, then the local population may decline. The main detriment to yapok-inhabited waterways, is the common mining which occurs throughout its range. Mining operations, such as the artisanal gold mining in French Guiana, directly pollutes yapok habitat simply through practice. A previous threat to the species was the yapok fur trade however, in recent years marsupial furs and pelts as a whole have greatly decreased in circulation. Overall, the yapok's threats are minor.

## Range and Population

The yapok is a new world marsupial that occurs in both North and South America. It lives at elevations of up to 1.8km (1.1mi) in mountainous forested habitats. Over everything, the yapok shows a preference for inland wetlands and other water bodies, where they occur most prolifically in rainforest environments. The species inhabits multiple countries over a wide range, including its northern-most range in Mexico to its southern-most in northeast Argentina and northern Uruguay. It is most common in Central America and least common in Venezuela however, the species is rare overall. Throughout its range the yapok is separated into four subspecies, which all inhabit exclusive regions and areas. For example, ***(Chironectes minimus argyrodytes)*** is found throughout Central America, in Mexico, Honduras and El Salvador, whereas ***(Chironectes minimus bresslaui)*** is found in Paraguay, northeastern Argentina and parts of northern Uruguay and southern Brazil. The yapok is uncommon and its population is unknown and likely in decline.

## Behaviour

Yapoks are solitary nocturnal mammals, similarly to most small marsupials. They have been seen operating in the day however, this is uncommon. The largest groups that yapoks are known to form, consist only of a male-female pair and their offspring. Yapoks are a territorial species and usually exhibit aggressive behaviours, notably when being handled. Due to this nature, it is likely that home ranges are fairly large however, their average size is currently unquantified. The typical distance between two burrows on a singe bank ranges from 844-3,388m (2,769-11,115ft), suggested some territory overlap. Male individuals are far more territorial and as a result, their home ranges can likely reach four times the size of a female's. Across its range, the yapok's breeding season varies depending on the subspecies. Individuals in Venezuela breed during January, July and November, while individuals in Brazil breed from February-December and finally, Argentine individuals breed exclusively in August. Females are polyestrous and breed 2-3 times a season, birthing a litter of 3-4 offspring each time. After birth, the neonates climb into the mother's pouch to begin nursing. They mill remain in the pouch for 38 days, at which they will begin to exhibit pigmentation and mill open their eyes. At this point in time, the juvenile yapok will be too large to continue inhabiting the pouch however, they will continue to nurse. They reach independence from their mother after 40-65 days however, they maintain a close social bond. When a mother yapok carries her young on her mammae, the male will often circle her, as a method of defense. If the mother is submerged, her pouch stays watertight, as to prevent drowning her young. This organ, known as the pars pudenda is a specialised form of pouch that also appears on the males however, there it is used to hold his genitals and protect them while diving. It can be noted that the relationship between a mother yapok and her young is extremely important, as the young are completely dependent on her for at least 40 days. During this time, the young will nestle their mother and sleep with her often. They may even climb on her back as a form of transport.

### Relationship with Humans

The yapok was once commonly harvested for fur however, demand for the product has decline exponentially in South America, with the exception of Peru.

## In Captivity

The yapok is kept in captivity consistently in a few South American zoos however, more popularly, it has been housed on and off at the Dallas World Aquarium, USA and Zoológico Miguél Álvarez del Toro, Mexico (commonly abbreviated as ZOOMAT). The yapok has exhibited consistently territorial and aggressive behaviour in captive environments, especially when handled.

## Sources

* IUCN Red List of Threatened Species - https://www.iucnredlist.org/species/4671/22173467
* Water Opossum | Animal Diversity Web, University of Michigan Museum of Zoology - https://animaldiversity.org/accounts/Chironectes\_minimus/
* Water Opossum | Wikipedia - https://en.wikipedia.org/wiki/Water\_opossum
* South American Marsupials | ZooChat Forums - https://www.zoochat.com/community/threads/south-american-marsupials.420387/
* Dallas World Aquarium 2010 | ZooChat - https://www.zoochat.com/community/media/dallas-world-aquarium-2010.211935/