Benzoic acid occurs naturally as do its esters in many plant and animal species. Appreciable amounts have been found in most berries (around %). Ripe fruits of several Vaccinium species (., cranberry , V. vitis macrocarpon ; bilberry , V. myrtillus ) contain as much as –% free benzoic acid. Benzoic acid is also formed in apples after infection with the fungus Nectria galligena . Among animals, benzoic acid has been identified primarily in omnivorous or phytophageous species, ., in viscera and muscles of the rock ptarmigan ( Lagopus muta ) as well as in gland secretions of male muskoxen ( Ovibos moschatus ) or Asian bull elephants ( Elephas maximus ).