Similar to many herbivorous mammals, B. Pygmaeus have multichambered stomachs. Their stomachs are filled with symbiotic bacteria, that can break down cellulose. The digestion process in this species, and can take up to a month to digest one meal. It is hard for this species to digest food due to a diet consisting of mangrove leaves are hard to process, and their body temperature can fluctuate daily. They practice thermoregulation- and depend on chemical processes used by bacteria in the gut in order to digest food. As temperature decreases so does their body temperature, and this decreases the rate of digestion. Pygmy sloths and other sloth species can even starve to death even with a full stomach due to how long it takes for their food to pass through the gut. These sloths have adapted to problems of leaf digestion in a few ways. First, their stomach has complex pouches that allow for storing bulky foods. These pouches separate food in different stages of digestion and fermentation. Next, in the morning it is common for them to be out in the sun to increase their body temperature and exposing their bellies.

Most mammals have seven vertebrae in their neck- B. Pygmaeus have 10 vertebrae in their neck. These “extra” vertebrae actually come from the rib cage. The bottom neck vertebrae of these sloths develop in a similar manner as the top of the rib cage in other mammals. This could come from having such a slow metabolism- this could come with mutations that add body parts to necks. One benefit of these extra vertebrae allow this species to gain a wider range of movement- they can “swivel” their neck up to 270 degrees in either direction. This benefits sloths in that it allows them as the slowest moving mammal to see predators, mates, and provides support when hanging upside down from trees.