Didelphimorphia, from the Greek δι (di, “two, double, twice”), Greek δελφύς (delphys, “womb”) and Greek μορφή (morphē “form, shape, appearance”), means "double-wombed", in reference to the fact that these animals have bifurcated genitals (bifurcated penises and bifurcated vaginas).

Common names of members

Opossums.

Distribution 

Mostly in Central and South America, except 1 species (Didelphis virginiana), which occurs in North America. 

Size

Their sizes range in small and medium size, from 10 cm to 75 cm length.

Morphology

Most of them are gray or brown in color, with black eyes and long ears, long snouts, a narrow braincase, and a prominent sagittal crest. Most have a prehensile tail and some have a marsupium, the pouch.

Ecology & Habitat

Most of them inhabit wet-closed (e.g., rainforest, mangroves, swamps) and mesic-open (e.g., grasslands, savannahs) ecosystems.

Diet

It is an unspecialized omnivorous group, feeding on vertebrates (frogs, rodents, birds, lizards, carrions), invertebrates (bugs, worms, snails), and plant matter (fruits and leaves). Four dietary classes are defined: general omnivores, omnivores with fruit preference, omnivores with invertebrate preference and omnivores with vertebrate preference.

Reproduction They are polygynous (one male mating with multiple females). Many species are semelparous: males die shortly after mating, females die after weaning their first litter.

The new born have strong arms with well-developed claws. They will claw along the mammary region, entering the mother's pouch and attach to a nipple. When they grow too large, they will leave the pouch and crawl on their mother's back. They are weaned and become independent after 2-4 months.

Total species known

111

Species in the collection

1

Species in Hong Kong

0

References

- Silva-Neto, F. C., Pavan, S. E., Astúa, D. (2023). Evolution, divergence, and convergence in the mandibles of opossums (Didelphidae, Didelphimorphia). Current Zoology, zoad027. https://doi.org/10.1093/cz/zoad027.

- Chemisquy, M. A., Tarquini, S. D., Romano Muñoz, C.O., Prevosti, F. J. (2021). Form, Function and Evolution of the Skull of Didelphid Marsupials (Didelphimorphia: Didelphidae). Journal of Mammalian Evolution, (3)28, 23–33. https://doi.org/10.1007/s10914-019-09495-4. 

- Mitchell, K. J., Pratt, R. C., Watson, L. N., Gibb, G. C., Llamas, B., Kasper, M., Edson, J., Hopwood, B., Male, D., Armstrong, K. N., Meyer, M., Hofreiter, M., Austin, J., Donnellan, S. C., Lee, M. S. Y., Phillips, M. J., Cooper, A. (2014). Molecular Phylogeny, Biogeography, and Habitat Preference Evolution of Marsupials. Molecular Biology and Evolution, 31(9), 2322–2330. https://doi.org/10.1093/molbev/msu176.

- Bradshaw, C.J.A., McMahon, C. R. (2008). Fecundity. In S. E. Jørgensen, B. D. Fath (Ed.), Encyclopedia of Ecology (pp. 1535-1543). Academic Press. https://doi.org/10.1016/B978-008045405-4.00645-5.