Short-Tailed Opossum


Short-tailed Opossum
The short-tailed opposum is a marsupial without a pouch.

Short-tailed Opossums (Monodelphis domestica) are small rat-like marsupials that are found in South America. There are 17 species of short-tailed Opossums in two sub-genera. The one we will deal with in this text is the most popular one found as an exotic animal in the United States, the Domestica. They are mainly localized in Brazil and adjoining countries. These little animals are frequently found in human dwellings and are welcomed there by the residents because of their voracious appetite for insects and rodents. They are also quite capable of destroying scorpions and spiders.

The short-tailed Opossum of the species Domestica is normally gray to brown in color with soft, thick luxurious fur. The underside is generally lighter in color. The males usually tend to have a thicker hair coat than the females. There are some variations in color and these animals seem to frequently have color mutations in the form of tans, mixed gray and tan and buff/gray. Some individuals also have white markings on the feet and throat. Their tails are naked but not scaled as in some rodents. A full-grown adult will weigh 3-4 ounces, and is 4 to 6 inches in body length with a tail about 2/3 as long as the body or occasionally as long as the body. The tail is prehensile and can not only be used as a means of balance when climbing and anchoring the animal to a tree branch, but it can also be used as another hand to carry nesting materials. Their muzzles are pointed and rather rat-like. Their dentition is i5/4, c1/1, p3/3, m4/4 x 2 for a total of 50 teeth.

Their teeth are very sharp. Their ears are large and thin-skinned. They have five digits on each foot with the large toe on the hind foot, considerably larger and without a claw. All the rest of the toes have claws. Their rear legs are longer than the front legs. The females do not have the expected marsupial pouch, but they do have a circle of nipples hidden by their fur on the abdomen. These nipples are not visible unless the female is lactating, about to give birth or the fur is separated. Males have the usual marsupial placement of testicles, between the navel and the penis. The testicles are fur covered. The female has a genital opening next to the anus which is not easily visible.

The short-tailed Opossum matures about 4-5 months and is ready to start a family. The female is often aggressive to any male unless she is receptive for breeding. Breeding can take place during any time of the year. Estrus lasts 3-12 days, cycling every 2-4 weeks. This Opossum can have up to four litters a year. After a brief gestation of about 2 weeks, the offspring are born and crawl to the teats on the female's abdomen. The babies born can number up to 16 but the only ones that can survive are those that attach to the teats. If the female has 12 nipples, only twelve can survive. The offspring attach to the nipple (which swells in the baby's mouth) and remain on the female's abdomen for over 30 days. If the baby is detached during this time, it will perish because the nipple stays enlarged and the baby is unable to re-attach. The babies continue to nurse for some time and are weaned at 6-8 weeks. According to Walkers' Mammals of the World, the females can breed up to 28 months and the males to 39 months.

Short-tailed Opossums can become loving and gentle pets if handled from a young age. Even some adults adapt readily to handling. These animals can be aggressive to each other after puberty, so if several animals are to be kept together, there must be in a large enclosure with several nest boxes and their behavior must be closely monitored. They may damage each other's ears and in some instances have even killed each other. They are not communal animals in the wild or in captivity. The mother carries her babies on her abdomen until about 30 days of age at which time the babies begin to climb and ride on her back. They do this until the poor little lady is carrying babies that weigh a collective total of more than she does.

Housing for a short-tailed Opossum as a pet might be quite different than for one in a breeding situation. A pet might be kept in an aquarium with a lid that has clamps to hold it down or a wire cage with small openings between the wires. These animals are adept at finding THE only way out of an enclosure so that they can relocate somewhere in your house. Some breeders keep them in Rubbermaid( blanket containers with plenty of vent holes drilled in them. Bedding should be either shavings or corn cob bedding. They are relatively neat with their toilet habits and use one portion of their enclosure for feces and urine which can be easily cleaned. They need a nest box, branches for climbing and exercising and even a small hamster exercise wheel. Some material for building a nest such as cotton batting and/or shredded paper will be appreciated and used. They are adept at weaving and fluffing a tiny amount into a wonderful, warm nest.

A water bottle should be provided. Try both the one with the glass tube and the steel ball bearing. Some of these Opossums have trouble obtaining water when licking the large stainless steel ball bearings so you may need to use a bottle with a small spout. There are several schools of thought about diets when raising these animals. One breeder, a naturalist, feeds meal worms, crickets, fruit and bread. Another, interested in a non-live, pelleted diet uses fox pellets (reproduction) by Milk Specialties Co. Another uses Exotic Canine( diet and Zoo "A" Diet( by Purina Mills. Some breeders have told me they mix kitten food in with the adult food when the babies are beginning to show interest in solid food, because it is tiny and easy for the weanlings to eat. Most give a bit of fruit every day or every other day to each animal that is on dry food. This is welcomed and relished. It is absolutely imperative that the water dispenser is checked often so the animals so not become dehydrated in case there is an equipment failure.

If a baby detaches from the mother's teat too early, it probably will not be possible to save it. If you must raise an older baby that is not yet weaned, try to foster it to another mom with babies or possibly a mother rat. Once the babies have been weaned by the mother, they have already made great progress eating the same food she eats. When weaning babies, be sure that your cage is large enough so they have a place to escape from each other in case one or more become aggressive. Several nest boxes, branches, and hanging ropes will give them a lot to explore and play with. A small hamster wheel might give them another activity to redirect any hostility. Also include some shredded paper to get them interested in building nests.


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