Opossums are the only marsupials in North America, meaning that they do not have placentas but develop their young in a pouch like a kangaroo or Tasmanian devil.
Opossums actually have an opposable digit on their hindfeet, giving them the ability to handle arboreal life, although many tend to remain on the ground.
Females can give birth to over 50 young between the months of March and August. Most of these will die on their way to finding a teat, or never find a teat due to lack of availability. This ensures that the strong will survive. The final litter size usually ranges from 1 to 15, but usually averages around 10. Gestation is 13 days long and then the young stay in the pouch another 2 months. The eyes open in 58 to 72 days and they are weaned and on their own at approximately 5 months of age.
If you find a baby opossum that is less than 8 inches long, it is considered an orphan. This is because a baby opossum would not be found outside of the pouch under normal circumstances. The orphaned baby should be brought to the Wildlife Medical Clinic or to the nearest rehabilitator. As the opossum gets older (at about 80 days of age), it will come out of the pouch and will be seen clinging to the mother’s side or her back. Baby opossums that are at least 8 to 9 inches long from the nose to the base of the tail are on their own.
Opossum body temperature is 90-99 degrees. They have a lower body temperature than most mammals.
Always check a dead opossum for babies. Just because the mother is dead doesn’t mean the babies are! But they will be if you don’t check. If there are babies in the pouch, try to pull the babies off the mother, if you can’t, transport the mother and babies to the nearest rehabilitator.
Opossums are very necessary animals to our environment. They are scavengers and help keep the earth clean. They feed on carrion, or road kill, invertebrates such as bugs, fruits, and small vertebrates.
Opossums are nocturnal (active at night) and have a solitary life. They are usually non-aggressive and prefer to “play possum” or fake death. When frightened, hey hiss with their mouths gaping open and excrete foul-smelling feces and a thick green gel-like substance. But remember, just because a species is characteristically non-aggressive, some individuals can be aggressive and will attack. Care should always be taken when working with wild animals.
Opossums are carriers of leptospirosis, a bacterial disease that starts off with flu-like symptoms. If left untreated, leptospirosis will cause kidney damage, menigitis, liver failure, and respiratory complications. The disease is transmitted through the urine and feces. It infects other mammals including cats, dogs, and humans. To prevent infection, keep pets vaccinated against leptospirosis and use bleach to clean up urine and feces. Wear gloves when cleaning up urine and feces and wash hands with soap and water afterwards.