Short-tailed Opossum
Monodelphis domestica

Description:  Short-tailed Opossums are small opossums which are covered with grey fur over most of their bodies.  Their tails are hairless.  They have large eyes and thin, sensitive ears.

Size:  A full-sized Short-tailed Opossum is 4-6 inches long and weighs 2-5 ounces.  Males are slightly larger than females.

Individual animal information:  The Short-tailed Opossum at Cosley Zoo is a male who was born in September 2007.  He was received from Miller Park Zoo in Bloomington.  Because Short-tailed Opossums are not native to Illinois, he is not on display at the zoo and is used only for educational programs.

Adaptations: 

• Short-tailed Opossums have a prehensile tail, which is able to wrap around and grab items such as tree branches.
• Short-tailed Opossums are marsupials, mammals which are born at a very early developmental stage and finish development outside the mother’s body while attached to one of her nipples.  Although many marsupials (such as kangaroos and koalas) have pouches in which they carry their young, Short-tailed Opossums do not.
• Short-tailed Opossums have opposable big toes, meaning that their big toes can rotate to touch the other toes on the same foot (similar to our thumbs).  This makes these animals exceptionally dexterous.
• The pads on the feet and toes of an opossum enable it to grip onto and climb up smooth surfaces.

Diet:  Wild Short-tailed Opossums feed on insects, fruit, and vegetables.  The Short-tailed Opossum at Cosley Zoo is fed a processed insectivore (insect-eater) diet, fruits, vegetables, crickets, and mealworms.

Reproduction:  Short-tailed Opossums become sexually mature at 4-5 months of age.  They can breed at any time of year, producing 4 litters annually.  Each litter can contain as many as 13 young possums.  The gestation period is about 2 weeks and the young are born at a very early stage of development.  After birth, the mother will stay in the nest for 4 weeks, during which time the young will attach to her nipples and stay there constantly as they continue to develop.  After that time, they climb onto the mother’s back, where they stay for 4 more weeks before becoming independent.

Shelter and space needs:  Wild Short-tailed Opossums are found in forests in Brazil, Bolivia, and Paraguay, and spend most of their time in trees.  They are also kept as exotic pets by people in the United States.  In captivity they require secure enclosures which are kept in areas free from drafts and contain several climbing structures.  Short-tailed Opossums are solitary animals that can become dangerous to one another if kept in groups.

Life expectancy:  4-8 years in captivity.  Life expectancy in the wild is uncertain.

Relationship with man:  Wild Short-tailed Opossums are considered to be good luck by the South Americans who live near them.  They help to remove pests such as insects, rodents, and scorpions from peoples’ homes.  Short-tailed Opossums are also used in laboratory research.  Studying them can produce useful information on cell development, since their young are born at such an early developmental stage.  They are also used for studies on cholesterol, genetics, skin cancer, and spinal cord injury repair.  In addition, these animals are kept as exotic pets.
               
Fun Facts:

• A young Short-tailed Opossum is born at a developmental stage that is equivalent to that of a 40-day old human embryo.
• Similar to the Virginia Opossum that is native to Illinois, a Short-tailed Opossum uses its prehensile tail to carry the leaves and sticks required to build its nest.
• The word “opossum” comes from the Native American word “apasum”, which means “white animal”.