Physiology

Lemurs are chordates which means they have internal skeletons that include a backbone. They are quadruped (have 4 feet) as well as a long tail. The ring-tailed lemur adult has 156 bones.

They have 3 types of muscle cells: skeletal muscle that aids locomotion, smooth muscle that lines the walls of hollow organs, and cardiac muscle found in the heart.

Their musculoskeletal system is adapted for a life swinging through trees as well as life on the ground. Their hands are well adapted to using fine motor skills.

Lemurs have a closed-circulatory system. This means that the blood is housed in blood vessels separate from the body's interstitial fluids. Lemurs have a 4-chambered heart that works to pump blood to the lungs to become oxygenated. The oxygenated blood then returns to the heart in veins, to be pumped out to the body's tissues in arteries, bringing oxygen and other important nutrients. The blood returns from the tissues carrying carbon dioxide. This blood is then pumped back to the lungs, where carbon dioxide is released and oxygen is picked up, where the cycle begins anew.

Lemurs have a complete digestive system that is similar other primates and humans. The digestive tract and supplementary organs are finely tuned to remove every useful nutrient possible from the food that is consumed. As the food travels from the mouth to the esophagus and then into the stomach, it is both mechanically and chemically broken down. The food moves into the small intestine where the pancreas and liver further aid in digestion and nutrients are absorbed. Material is then moved to the large intestine where the excess water is removed, and fecal matter is compacted and stored.

Lemurs do have a couple modifications to aid in their largely plant-based diet. The have enlarged salivary glands, and an elongated lower gut that facilitates fermentation.