Unique Among Ungulates
Hippos have a unique digestive system amongst ungulates, hoofed animals. They are neither ruminants, 4-chambered stomach with micro bacteria in the foregut, nor hindgut fermenters, single stomach with micro bacterial fermentation occurring last. Hippos have 3-chambered stomachs and practice foregut fermentation. This means that their food is exposed to micro bacteria that can break down the cellulose plant cell walls early on in the digestive process.
They do not, however, chew the cud as in ruminants and are essentially bulk grazers like hind-gut digesters.
Eat in Bulk
Hippos are grazers, they eat grass. They are not selective of which species they eat or which part of the plant they feed on. Their broad muscular lips allow them to pluck short grass which they ‘mow’ repeatedly or taller swathes of grass. They are noisy feeders. Sometimes hippos will eat water plants growing in the waterways where they reside
Hippos often nibble carcasses of dead animals floating in their waterways or lying on the banks. Some theories suggest that this behaviour stems from the omnivorous traits of their pig ancestor. Other theories suggest that hippos don’t have mouths suited to pulling off flesh and chewing it and that this behaviour is rather linked to kin recognition. Hippos are believed to be trying to cognitively recognize the deceased creature through the use of the chemo-sensitive Organ of Jacobsen located on the roof of the mouth.
The fact that hippo defecate in or near the water has an important ecological benefit. They are adding nutrients to the system, which can then be utilized by members of the food chain like fish and invertebrates.
Hippos harbour the bilharzia parasite in their bodies. This doesn’t seem to cause them any ill effect.
By Megan Emmett