Answer: microorganisms
Explanation: No animal has the ability to digest cellulose directly.
Most animals such as horses and termites cannot directly digest cellulose. The animals have a symbiotic relationship with bacteria in the intestinal tract. The symbiotic bacteria acts on the cellulose and secrets the necessary enzymes (cellulase) to digest cellulose in the intestinal tract. An example of such microorganism in a symbiotic relationship with animals that facilitates the digestion of cellulose is Trichonympha
