General Overview
The Hippopotamidae family consists of the hippopotamuses, large semi-aquatic herbivorous mammals native to sub-Saharan Africa. The family contains two extant species: the common hippopotamus and the pygmy hippopotamus. Despite their pig-like appearance, hippos are phylogenetically closer to cetaceans (whales and dolphins) within Artiodactyla. They are ecologically significant as ecosystem engineers, influencing riverine and floodplain environments through grazing and nutrient cycling.
Appearance
Hippopotamids have massive, barrel-shaped bodies supported by short, pillar-like legs. The head is large, with eyes, ears, and nostrils positioned high on the skull, allowing the animal to remain mostly submerged while breathing and monitoring its surroundings. Skin is thick and largely hairless, secreting a reddish fluid that functions as a moisturizer and antimicrobial barrier. The mouth is wide with large incisors and canines used primarily for display and combat rather than feeding.
Diet
Members of Hippopotamidae are primarily herbivorous grazers. The common hippopotamus feeds mainly on grasses consumed during nocturnal foraging excursions on land, sometimes traveling several kilometers from water. The pygmy hippopotamus has a more varied diet that may include leaves, shoots, and fallen fruit. Their digestive system is adapted for fermenting plant material but differs from true ruminants.
Habitat
Hippopotamids inhabit rivers, lakes, swamps, and floodplains. The common hippopotamus depends heavily on permanent water bodies for thermoregulation and skin protection, spending much of the day submerged. The pygmy hippopotamus prefers dense forested wetlands and spends more time on land relative to its larger relative.
Behavior
Common hippopotamuses are highly social, forming groups (pods) that occupy defined stretches of water dominated by a territorial male. They are mostly nocturnal grazers and can be surprisingly fast on land despite their size. Vocal communication includes grunts, roars, and underwater vocalizations. Reproduction occurs in water, and females give birth to a single calf after a lengthy gestation, with strong maternal care provided.
