Sexual dimorphism in body weights for Chironectes minimus. The horizontal lines indicate the average values. Results of linear models selection: " Sex effects. Abstract. We studied the population structure, spatial patterns, and activity patterns of the water opossum (Chironectes minimus) via. Learn more about the Water opossum - with amazing Water opossum videos, photos and facts on Arkive.


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The 2 pairs of bulbourethral glands of C. The tip of each hemi-glans is rounded and bulbous shaped, whereas the urethral grooves end at the ventral aspect of the tip of each half glans. It is found in tropical and subtropical areas and its distribution ranges from southern Mexico through Central America, Colombia, Venezuela, Guianas, Ecuador, Peru, Paraguay, and chironectes minimus the east coast of Brazil to northeastern Argentina Eisenberg and Redford Among chironectes minimus important anatomical reproductive structures of C.

Water opossum

The urogenital region of a juvenile female was described in detail by Hill and Fraser The urogenital sinus and rectum open separately at the surface indicating chironectes minimus there is no cloaca, at chironectes minimus in C.

To our knowledge, there is no detailed description of the male genital system of C. This study presents the 1st description of the morphology of the male genital system of C.

Materials and Methods Two adult and 7 juvenile male specimens of C. All specimens are housed in collections of Mastozoology of Brazilian museums.

The male genital system was dissected and examined in all specimens. Small sections of the genital organs were processed for histological study, embedded in paraffin, and stained with hematoxylin—eosin to confirm anatomical structures such as rete mirabile, bulbourethral glands, and the muscular arrangement chironectes minimus the anal and urogenital openings.

Results Externally, the male genital system is represented by the testes in a pendulous scrotum and chironectes minimus the urogenital preputial opening through which the urogenital system communicates with the exterior when the penis is exposed Fig.

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Chironectes minimus, the female reproductive system consists of the urogenital sinus opening and the marsupial pouch containing mammary glands and nipples Fig. The skin of the scrotum chironectes minimus scrotal peduncle is white, densely haired, and lacks pigmentation Fig.


The tunica vaginalis of C. In the standing position, the anus appears as an inverted Y-shaped aperture forming a ventral triangular fold Figs. Chironectes minimus are symmetrical as well, which distributes force equally along both borders of the webbing; this increases the efficiency chironectes minimus the water opossum's movement through the water.


The yapok's long tail also aids in swimming. Being a chironectes minimus and at the same time an aquatic animal, the water opossum has evolved a way to protect its young while swimming.

Water opossum videos, photos and facts - Chironectes minimus | Arkive

A strong ring of muscle makes the pouch which opens to the rear watertight, so the young remain dry, even when the mother is totally immersed in water. Reproduction[ edit ] Yapoks mate in December and a litter of young chironectes minimus born 12 to 14 days later in the nest.

In most studies, captures or sightings occurred mainly in forested streams with clear, fast-flowing waters. As for the breeding season, females with offspring were captured in January, July, and November in Venezuela Mondolfi and Padilla ; in Brazil, females with offspring were captured between December and February Nowak ; and in northern Argentina, the chironectes minimus of offspring was recorded in August Monteiro-Filho et al.

Nothing is known, among other subjects, about population structure, reproduction in the wild, spatial patterns home lengths and overlaps and habitat selectionand chironectes minimus patterns of water opossums.

In all these aspects, there are open questions as to whether the patterns shown by water opossums are similar to those found in other neotropical marsupials, due to phylogenetic constraints, or if they are similar to those shown by other semiaquatic mammals, indicating that ecology had a preponderant role in shaping these characteristics.

Because of their semiaquatic and nocturnal habits, water opossums have seldom been captured by the traditional methods used for other small mammal species Mondolfi and Padilla An efficient method for trapping the water opossum was only developed in Bressiani and Graipelenabling more thorough studies of their ecology.

The present study focused chironectes minimus the ecology of water opossums in Atlantic Forest streams in southeastern Brazil, attempting to fill some of the many gaps in the knowledge of this species and to test some hypotheses on its reproductive seasonality, spatial patterns, and activity patterns.

Regarding reproduction, we tested the hypothesis that water opossums show reproductive seasonality, as usual among neotropical marsupials Fleming ; Fonseca and Kierulff ; O'Connell ; Tyndale-Biscoe chironectes minimus Mackenzie

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