folivore

Folivore refers to an animal whose diet consists mainly of leaves. Folivory has evolved across diverse groups, including mammals, primates, insects, and some birds. Leaves pose digestive challenges: they are high in fiber and often contain anti-nutritive compounds, so folivores rely on specialized anatomy, physiology, and microbial fermentation to extract nutrients.

Digestive adaptations vary by lineage. Some have sacculated or multi-chambered stomachs that host foregut fermentation, such as certain primates; others rely on hindgut fermentation after a long small intestine. Koalas have long caecums and slow gut passage to maximize cellulose breakdown; sloths possess a complex stomach for microbial digestion. These adaptations enable extraction of energy and protein from leaves.

Leaves contain secondary compounds that can be toxic. Folivores detoxify and tolerate these compounds via specialized liver enzymes, selective feeding on less-defended foliage, and microbial partners that metabolize tannins and terpenes. Their low-energy diet is offset by long, steady intake and efficient nutrient extraction.

Ecology and behavior: Folivores often forage over extended periods, maintain relatively stable home ranges, and prefer young or nitrogen-rich leaves when available. Many are arboreal and rely on forest canopies; some terrestrial examples occur in open habitats.

Examples: koalas, sloths, and many colobine primates, as well as various ungulates and some insects exhibit folivory.