The kinkajou (Potos Flavus) is a mysterious mammal with a golden brown coat, big eyes, and a prehensile tail. This fuzzy mammal is known by many different names including the Golden Drinker, the Honey Bear, and the night walker.
Commonly mistaken to be a lemur, or a monkey the kinkajou is actually in the Family Procyonidae with racoons and coatis. Most of the mystery behind these animals comes from the fact that they are arboreal and nocturnal, both of which make them difficult to be spotted. Kinkajous live in Central and South American rainforests, and have recently been discovered as far up north as Mexico. Due to their warm climate they do not hibernate.
They are classified under the order Carnivora, but their diet makes them omnivores, specifically preferential frugivores that eat small animals, insects, roots, nuts, and eggs when fruit is not in season. Not much is known about these animals because in their natural habitat they are a difficult test subject to study, however they have recently come into the limelight as a popular exotic pet after Paris Hilton adopted one. This is making them more attainable and hopefully more research will come out about these exotic animals.
The kinkajou has a 5-7inch long tongue that they use for multiple things like to scoop the insides out fruit out, to catch insects with, and to reach inside beehives and flowers to get out the honey and nectar. This is how they earned the nickname Honey Bear and Golden Drinker. The Kinkajou’s love of honey makes it a crucial part of the ecosystem.; they are important pollinators. When they stick their long tongue into a flower to get out the nectar, pollen attaches to their tongue, face and hands. When they move on to the next flower they spread the pollen and deposit it onto the new flower.
The tongue is made of stratified simple squamous epithelium and has two types of papillae on the surface, filiform papillae and taste buds. The filiform papillae are rough projections on the tongue that are visible. In carnivores, these are used to strip the meat off of the bones of their prey. Although a kinkajou is a preferential frugivore small vertebrae remains have been found in their feces. The other type of papillae are the taste buds.
Another thing that makes kinkajous unique is their prehensile tail, which allows them to hang upside down from branches. This allows them to use both hands to grab food and bring it to their mouth. Kinkajous on multiple occasions have even been spotted eating upside down. These are unusual animals because although they are primarily frugivorous they have large canine teeth and small incisors similar to carnivores like minks and cats. As previously mentioned they are even classified into the order Carnivora despite their dietary preferences.
These large canines are useful for ripping flesh off small vertebrates which they have been observed eating when fruit is rare or not in season. They can also use these sharp canines to crack open nuts. They have brachyodont teeth and a dental formula of 2( I 3/3, C 1/1, P 3/3, M 2/2)= 36 . They have small cheek teeth (premolars and molars) which requires them to chew certain hard food like nuts and roots for 20 to 30 minutes.
After food enters the oral cavity mastication begins. Mastication in the kinkajou can differ greatly depending on the type of food they are eating. When eating soft fruit they use their tongue to scoop the meat of the fruit into their mouth. If it is soft enough, they do not chew it, they just swallow it whole. However, there are some foods they eat like nuts and tree roots that require extensive mastication where they chew by moving their jaws up and down.
Most carnivores do not contain digestive enzymes in their saliva, although there is no research to confirm whether or not kinkajous possess such enzymes. Once their food is broken up into small enough pieces it begins to make its way down the esophagus, in order to do this it must first pass through the epiglottis. The epiglottis is a small flap that covers the trachea to ensure that food doesn’t go down this tube which is only made for air. Once food leaves the oral cavity, it is considered a bolus and will be referred to as such.
There is no data on the histological composition of the kinkajou esophagus, but because kinkajous are closely related to raccoons and the raccoon esophagus is made primarily of skeletal muscle it is likely the kinkajou had a very similar esophagus. It would also make sense for a kinkajous esophagus to be lined with skeletal muscle because kinkajous are known for eating upside down the skeletal muscle allows them to control when to swallow. A majority of the esophagus is striated skeletal muscle, but it transitions into smooth muscle as it enters the stomach.
Once it becomes smooth muscle it is no longer under voluntary control. This lower part of the esophagus is made up of 4 layers from the most superficial to the tunica serosa. The tunica serosa is made of simple squamous epithelium. The tunica muscularis is the largest layer which is composed of two layers of muscle, longitudinal muscle and circular muscle, these two muscle layers help push the bolus down the esophagus through the use of smooth contractions called peristalsis.
The last and deepest layer of the esophagus is the tunica submucosa which is composed of loose connective tissue and glands. The glands secrete mucus, which lubricates the esophagus, making it easier for the bolus to travel down to the stomach. Digestive enzymes are also secreted to begin breaking down bolus further into nutrients the body needs.
After the bolus travels down the esophagus it must pass through the cardiac sphincter to reach the stomach. Not much is known about the particular stomach type of a kinkajou however, since they are classified in the order Carnivora it is likely that they have a simple monogastric stomach. The monogastric chamber is made up of four sections. The esophageal region is the region which is connected to the esophagus it is made of stratified squamous epithelium.
Lateral to this section is the cardia which as the name implies, is close to the heart. The body of the stomach is the fundus, this is the largest part and makes up the majority of the stomach. This part of the stomach is filled with mucus cells, which as the name implies produce mucus. This mucus is used to protect the stomach linings from the hydrochloric acid that is produced from the parietal cells.
Chief cells in the fundus also produce Pepsinogen, this is the inactive form of pepsin. Pepsinogen is converted to the active form pepsin when it comes in contact with hydrochloric acid. Pepsin then breaks down proteins. After the bolus has been processed in the stomach it moves down to the last part of the stomach the pylorus. The pylorus is an area where the stomach and the small intestine meet.
The bolus must pass through the pyloric sphincter in order to reach the small intestine. Once the bolus passes through the pyloric sphincter it reaches the duodenum, which is the first part of the small intestine. The duodenum is lined with mucosal glands, this helps protect the small intestine lining from stomach acids. The duodenum is also lined with villi but they are not as large as the villi farther down in the small intestine. This is because the duodenum is where digestion of the bolus occurs.
Many enzymes are secreted into the duodenum from accessory organs to aid in the breakdown of the bolus. The kinkajou does have all the typical accessory organs like the gall bladder, pancreas, and liver. The gallbladder stores bile and sends it to the small intestine where it then reacts with the bolus and breaks down fat. The exocrine region of the pancreas produces mucus and bicarbonate both of which help combat the low acidity of the stomach.
The endocrine portion of the pancreas also produces insulin and glucagon to regulate blood glucose levels, but this doesn’t involve the small intestine. The liver produces the bile, which it can send through the cystic duct to the gallbladder for storage or to the duodenum to break down lipids. After the duodenum the bolus travels into the longest part of the small intestine, the jejunum. The jejunum has very large villi to increase surface area. Increased surface area is necessary in the jejunum because this is where the absorption of nutrients occurs.
After all the nutrients are absorbed and sent to the body to be used the bolus travels to the final part of the small intestine which is the ileum. The ileum has some villi as well, but they are not as prominent as they are in the jejunum. The ileum has villi because some final absorption occurs here before the bolus is sent to the large intestine. When the bolus reaches the large intestine, it is in the final stage of the digestion path and is being prepared for excretion. Here the water is absorbed out of the bolus, the amount of water absorbed is regulated by the kidneys.
The large intestine is only made up of the colon and the rectum because Kinkajous do not have a cecum. Due to similar species in class Carnivora as the kinkajou it is likely that the kinkajou does not have a very large colon. The bolus is now just considered waste product or feces at this point. The rectum is the last part of the large intestine where feces are stored. Feces will be stored here until the anus relaxes causing it to dilate large enough for the feces to pass through.
The anus a sphincter made up of smooth and skeletal muscle. This allows it to relax through conscious or unconscious control. Due to kinkajous emerging as popular exotic pets, there have been a lot of new digestion problems reported due to kinkajous being fed items they are not meant to eat. For example Kinkajous should not be fed Dairy, it is not found in their natural habitat and their bodies do not have enough lactate to break down lactose.
There have also been many reports of kinkajous having bad reactions to strawberries. It is suspected that strawberries may even be a common allergen to kinkajous. Overfeeding kinkajous is another problem that owners of these exotic pets must be aware of because it can cause gastrointestinal disease.
The digestive tract of the kinkajou is not well researched, however they are known for having an extremely rapid digestive tract. In a study by Joanna E. Lambert, et al. it is shown that on average it takes 2.5 hours for food to pass from the oral cavity and out through the anus. This could be due to their digestive tract being simple and relatively short as in most carnivores but primarily fruit passing through it.
This rapid digestion also causes frequent defections especially after meals, the frequency of defecation is directly linked to food consumption. Kinkajou feces play an important role in plant propagation as well because a majority of the time seeds from the fruits they eat pass through the digestive system intact. When a kinkajou travels to different areas and defecates the seeds are dispersed in a new region.
