Ida Singer, age 12, of Philadelphia, Pennsylvania, for her question:

Are our opossums and raccoons related?

Both these native North Americans are about the size of large house cats. They share the same woods and waterways, compete for similar foods and prefer to hunt after dark. In the late evening, by a dimly lit stream or perched on a shadowy bough, their dusky fur coats blend and blur with the scenery. Then it is hard to distinguish the raccoon from the opossum. But a closer  inspection in a good light reveals that they are not even distantly related..

Zoologists classify animals by such basic features as teeth and offspring. Our native raccoons and opossums share several external features and somewhat similar life styles. To some extent they compete for a mixed diet of meat and vegetables, though the fussy raccoon washes his fresh food and the opossum sometimes devours carrion. The opossum has 50 teeth, including six more incisors and eight more molars than the raccoon has. The raccoon's dental structure includes only 40 teeth, with fewer incisors end molars but more premolars than the opossum's.

Both have agile little five fingered hands and five toed feet, though the opossum's big toe can grasp like a thumb. Both have long tails. But the raccoon's thick brush is ringed with eye catching light and dark circles. It may be the handsomest tail in the woods, though he uses it mainly for balancing purposes. The opossum's ratty string is a very handy prehensile tail, used to grasp and hang onto the boughs and branches.

Variations in teeth, toes and tails disqualify the two animals from close kinship. Their style of childbearing and rearing sets them even farther apart. Mrs. Raccoon carries her unborn young for about nine weeks. The four or so infants wear fuzzy fur coats and black family eye masks. They open their bright eyes in about 19 days and soon venture from their cozy nest on short field trips. But they remain under patient parental care for about a year.

Mrs. Opossum carries her unborn litter of 18 or so for less than two weeks. The helpless, bitsy babes spend ten weeks inside the double pouch on her tummy, then ride on her back, clinging perilously to her scrawny fur. They develop fast, though only six or so survive the hazards of infancy. These are ready to fend for themselves in 14 weeks. Mother Opossum has time for two litters during the season, while patient Mother Raccoon has time for only one.

Both the raccoon and opossum are rated as mammals because their infants are fed on mother's milk. But opossums belong in the order of pouched marsupials. The family name of our native opossum is Didelphidae, named for the mother's double bassinette. Our raccoon belongs in the order of carnivores and his family name Procyonidae is named for the Dog Star. His outstanding visual features are his bushy ringed tail and his foxy face with the black Mardi Gras mask. The opossum has a long snoopy snout and a ratty tail.

Watching their behavior, you soon notice a great difference in intelligence. The raccoon is a fearless, super smart fellow. The opossum is rather a muddlehead and so timid that when facing a foe he falls into a dead faint. This panic reaction accounts for his survival. For his carnivorous enemies mistake him for a corpse and most of them ignore him because they fancy only freshly caught meat.