Let's start with carnivores like humans and dogs. There are three basic phases to carnivore digestion. The cephalic phase is the chewing and tasting of the food in the mouth, the gastric phase is the breakdown of the food by acids in the stomach, and the intestinal phase is the...
Let's start with carnivores like humans and dogs. There are three basic phases to carnivore digestion. The cephalic phase is the chewing and tasting of the food in the mouth, the gastric phase is the breakdown of the food by acids in the stomach, and the intestinal phase is the absorbing of nutrients in the intestines and the passing of waste through the system. We will focus on the gastric phase, and what you eat will determine how long the digestion takes. Fats take the longest to digest (4-6 hours), meat protein is next (3-4 hours), vegetables are next (30-45 minutes), and finally fruits (20-30 minutes).
Herbivores have differences in their digestive systems compared to carnivores. Ruminants are a class of herbivore that have a four chambered stomach and include cattle and sheep. The first two chambers (the rumen and reticulum) mix the chewed plant material with saliva for initial digestion. The liquid is then separated from the solids, and the collected solid clump (called the cud) is then regurgitated back to the mouth for additional chewing. The food eventually reaches the third chamber (the omasum) for uptake of water and minerals, and finally the fourth stomach (abomasum) which is like a carnivore's stomach. The cellulose in the plant material they eat is very difficult to digest (humans cannot digest it). Microbes in their stomachs allow the herbivores to slowly digest the cellulose. Also, herbivores must each much more constantly since there is less nutritional material in the plants they eat versus a carnivore's diet. As a result, their digestive times are longer than carnivores (it takes the better part of a day).
I cannot find any specific information on the honey possum, though it is a nectarivorous mammal, meaning that its diet consists entirely of nectar. Since nectar is basically a sugar containing liquid, I would think that it would be digested much more quickly that an herbivore's diet since sweet sugars are relatively simple compounds to digest.