Omnivore preferably dry bones, for particular minerals and nutrients. Felines, which are usually regarded as obligate carnivores, occasionally eat grass to regurgitate indigestibles (e.g. hair, bones), aid with hemoglobin production, and as a laxative. Occasionally, it is found that animals historically classified as carnivorous may deliberately eat plant material. For example, in 2013, it was considered that American alligators ("Alligator mississippiensis") may be physiologically omnivorous once investigations had been conducted on why they occasionally eat fruits. It was suggested that alligators probably ate fruits both accidentally but also deliberately. "Life-history omnivores" is a specialized classification given to organisms that change their
Herbivore adaptations to plant defense adaptation is only increasing in these insects. Herbivores are unable to digest complex cellulose and rely on mutualistic, internal symbiotic bacteria, fungi, or protozoa to break down cellulose so it can be used by the herbivore. Microbial symbionts also allow herbivores to eat plants that would otherwise be inedible by detoxifying plant secondary metabolites. For example, fungal symbionts of cigarette beetles ("Lasioderma serricorne") use certain plant allelochemicals as their source of carbon, in addition to producing detoxification enzymes (esterases) to get rid of other toxins. Microbial symbionts also assist in the acquisition of plant material by weakening a host plant's