Impurest's Guide to Animals #136 - Yapok

It’s the last week of August and things are looking grim and gloomy as I head into a five day cycle of bat surveys. Last week the peace was shattered by the Paradise Flying Snake, an animal that surprised us all by taking to the skies. This week a mammal follows suite, this time taking the plunge into the streams and pools of the rainforest. Hope you guys enjoy.


Issue #136 - Yapok


Kingdom – Animalia

Phylum – Chordata

Class – Mammalia

Order – Didelphimorphia

Family – Didelphidae

Genus – Chrionectes

Species – minimus

Related Species – The Yapok or Water Opossum is one of over 90 species of marsupial found in the order Didelphimorphia (1)



Marsupial Otter?

The Yapok is a medium sized marsupial, with a body length of around 30cm, with an additional 40cm long tail. The Yapok’s dense waterproof fur has a marbled pattern of grey blotches against a dark background that runs from the base of the tail to the base of the animal’s ears. Whilst the animals back feet are webbed to aid in swimming, the fingers of the front feet are fully mobile and are used to grab and manipulate prey. To aid in the detection of submerged obstacles, the Yapok has sensory bristles (in addition to the whiskers) mounted in tufts above each eye.


Yapok are carnivorous and do the majority of their hunting in water, using their long nimble fingers to grab frogs, fish, snails and other freshwater invertebrates to consume on shore. While the exact predators of the Yapok are undocumented (outside a few species of birds of prey) it can be assumed that cats such as Ocelot (Leopardus pardalis) and Jagurundi (Puma yagouarpundi), along with the larger species of snake such as the Bushmaster (Lachesis muta) are potential predators. To reduce the risk of predation the Yapok spends the entire day in its burrow and only emerges to hunt for prey at night.

Yapok are solitary, only coming together to breed during the months between November to Feburary, with the exact date varying from country to country. After breeding the female will give birth to a litter of up to five joeys which remain in the mothers pouch for the first month of their lives (2). Due to the species aquatic habits, certain modifications to protect the joeys are in place, and the females pouch is able to seal itself with a ring of muscle to prevent flooding. Young Yapok mature quickly, and once they’ve grown their adult teeth they are able to leave the nest and establish their own territories.

Five Fun Yapok Facts

The name Yapok comes from the local name of the Oyapock River in Northern Brazil, and is possibly where the species was first seen by Colonial Europeans

The Yapok is one of two aquatic masupials, the other being the Lutrine Opossum (Lutreolina crassicaudata) although the species isn’t as adapted to riverside life as the Yapok

The Lutrine Opossum [4]
The Lutrine Opossum [4]

The Yapok is also the only extant species of marsupial where both the male and female have pouches. The male’s is less waterproof and is used to store his genitals whilst swimming and diving (3)

In addition the Yapok is the only species of Opossum that doesn’t have a cloaca.

Fossil remains of the Yapok date back to the Pliocene Epoch (5 to 2.75 MYA)


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2 - Julien-Laferriere, D., M. Atramentowicz. 1990. Feeding and Reproduction of three Didelphid Marsupials in Two Neotropical Forests (French Guiana). Biotropica, 22: 404-415.

3 - Nogueira, José Carlos, et al. "Morphology of the male genital system of Chironectes minimus and comparison to other didelphid marsupials." Journal of mammalogy 85.5 (2004): 834-841

Picture References

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Hmm all these animals in weird situations, it’s kind of confusing no? Next week we’re beach bound as we relax and enjoy the last days of summer, until then make sure to critic, comment and suggest future issues as well as making sure you check past issues in Impurest’s Bestiary.

Many Thanks

Impurest Cheese

Want more IGTA? Click here for more marsupial madness with the tenacious Tiger Quoll. Or if you like river creatures click here to meet the murderous monster the Mata-mata