Perissodactyla, from Greek περισσός (perissós, “uneven”) and Greek δάκτυλος (dáktulos, “a finger, toe”), means “uneven-toed”, in reference to the fact that these animals typically have reduced the weight-bearing toes to three or one of the five original toes (though tapirs retain four toes on their front feet). The nonweight-bearing toes are either present, absent, vestigial, or positioned posteriorly.

Common names of members

Horses, asses, zebras, tapirs and rhinoceroses.

Distribution 

Central and South America, eastern and southern Africa, and central, southern, and southeastern Asia.

Size

Their size vary from 1 m tall and 100 kg of weight up to 2.5 m and 1,000 kg

Morphology

Equines: their lengthy necks and heads define them all. Their weight is supported by one digit (which developed from the middle digits) on their thin legs. Most equines have erect manes and long tails that culminate in a tuft of hair, with the exception of domestic horses, who have long tail hair extending from the top of the tailhead or dock.Tapirs: they have spread, hooved toes, with four on the front foot and three on the hind foot, a tiny proboscis, oval, white-tipped ears, and rounded, projecting rumps with short tails. With the notable exceptions of the Malayan tapir, which has a white, saddle-shaped marking on its back, and the mountain tapir, which has longer, wooly hair, all of them have short coats that range in color from reddish brown to gray to practically black.Rhinoceroses: Their huge bulk, stumpy legs, and either one or two dermal horns are what make them instantly recognizable. Certain individuals may have short or inconspicuous horns. These animals can have colors ranging from slate gray to golden brown. Its tail bristles and ear fringes contain the majority of its body hair, with the remainder being sparsely scattered across the rest of the body.

Ecology & Habitat

Tapirs live alone, mostly in tropical woods. In Asia, damp marsh or forested environments are home to rhinos, who typically dwell alone in arid savannas. Horses thrive in herds and like open spaces like semi-deserts, steppes, and grasslands.

Diet

They only eat grass, leaves, and other plant parts to varied degrees as herbivores. It's common to distinguish between feeders that feed mostly on grass (white rhinos, equines) and feeders that feed on leaves (tapirs, other rhinos).

Reproduction 

Seasonally polyestrous, typically giving birth to just one young, these animals have a lengthy gestation period and a tiny litter size. Rhinos have the longest gestation period, lasting between 330 and 500 days. Precocial refers to the fact that young perissodactyls are born already somewhat autonomous; for instance, young horses can start following their mothers within a few hours after birth. The infants are breastfed for a considerable amount of time — typically into their second year — until they attain sexual maturity at the age of eight or ten.

Total species known

3

Species in the collection

1

Species in Hong Kong

0

References

Pough, F. H., Janis, C. M., Heiser, J. B. (2012). Vertebrate Life. Pearson.

Macdonald, D. W. (2006). The Encyclopedia of mammals. Oxford University Press. https://doi.org/10.1093/acref/9780199206087.001.0001. 

Wilson, D. E.; Reeder, D. M. (2005). Mammal Species of the World: A Taxonomic and Geographic Reference. Johns Hopkins University Press.