Species Profile: Didelphis virginiana – Virginia Opossum
Scientific Name: Didelphis virginiana
Common Name(s): Virginia Opossum, Possum
Virginia opossums Didelphis virginiana are the only marsupial (mammals with a pouch) in North America. They are small to medium in size and have mixed black, gray, and white fur. Their faces are white with a long pink nose, black eyes, and black ears. They have opposable thumbs on their hind legs which help them climb trees. The hind legs also do not have claws. Their tail is prehensile, meaning it can grab and hold things, and is used mainly for gripping limbs when in trees. A common misconception about opossums is that they hang from their tails to sleep. Although they can hang from their tails for a short time, it is not strong enough to hold them for that long. Males often weigh more and have larger teeth than females, while females have a marsupium (pouch) to hold babies. Opossums range from 10-40 inches in length, without tail, and weigh up to 8 lbs. for females and up to 14 lbs. for males.
These animals display characteristics that are very unusual for North American mammals. Among them are…
- Opossums are the only North American marsupial (development of young in a pouch)
- They have 13 nipples in a circular arrangement with one in the middle.
- Their brain is 1/5 the size of a raccoon of similar size.
- They have 50 teeth. More than any other North American Mammal
- They have a prehensile (grasping) tail.
- They have opposable thumbs on the hind legs
- No claws on hind legs
- Yes, they do play possum
- From an evolutionary standpoint they are not “living fossils” as they evolved recently (20 million years ago)
- Extreme example of Bergman’s Rule which states that individuals within a species are larger in colder climates to conserve heat. Northern opossums are up to 20 times larger than their southern cousins.