Article last updated on February 20th, 2019.
Anatomy of an African Pygmy Hedgehog
The anatomy is basically nothing more than how the body is made up. The shape of the head, number of bones in the body, the function of organs, all this knowledge is known as anatomy.
The head is slightly heart shaped, in which the perfect straight lines run from the bottom of the ears towards the sides of the nose. Alongside the bottom of the quill line, from those points on towards the middle of the head, is shaped like a 3 that’s tipped over.
The ears are round at the tips and each are shaped like a half oval. They are placed somewhat to the back and at both sides of the head. In between both ears is a small gap of 1 to 15 cm that is between two dorsal muscles. The quills here are slightly longer than on the rest of the body.
The eyes are roundly shaped and slightly bulge. They are placed slightly at the sides of the head when you draw a straight line from the middle of the ears to the middle of the nose. Some hedgehogs have visible eye white (the ‘sclera’) that’s seen as a blue rim around the eye.
The nose is slightly oval and flat, making it look like a pig’s nose. On the bottom of the nose is a small ‘dent’ where the mouth meets the nose.
Mouth & teeth
African Pygmy Hedgehogs have a relatively large mouth which has kind of a triangular shape. They have small, flat molars and a number of little, sharp teeth. In the front of their mouth, on the upper jaw, are two longer teeth which look like vampire teeth. With these, they can grab a prey with a quick death as result. There are also two larger teeth on the lower jaw, but they don’t stand out as much.
A hedgehog has a drop-shaped body. Overall, an African Pygmy Hedgehog can become 15 to 25 cm long and weigh between 250 and 600 grams. The flanks (sides of the belly) should run in a straight line, but might be a bit round-shaped when seen from above. When the flanks are slightly hollow, the hedgehog is underweight.
The belly contains tiny white hairs. The skin is visible through the fur in most cases and the genitals are clearly visible as well. With a female, the anus and the vulva are very close to each other, almost without space in between. With a male, the anus is placed right above the tail and the penis is placed in the middle of his belly. In grown males, this is easier seen than in younger hoglets, but the gender is not difficult to see either way.
The line between the fur on the belly and the quills on the flank, we call the ‘skirt’. An African Pygmy Hedgehog has approx. 4000 to 6000 quills on its entire body when the animal is fully grown.
An African Pygmy Hedgehog (Atelerix albiventris) is born with about 50 to 100 white and bendy quills, which at the birth are hidden under a thin layer of skin and come through after a couple of hours. As the hedgehog grows they go through a few phases in which quills fall out and new colored quills come through again. These quills become stronger, less bendy and intensify in color at each phase (which is called a quilling). The quilling phases can be seen at:
Two days of age
Now the first stronger quills will come through. They can be colored already, but some hoglets will keep the white quills for a while longer.
Two weeks of age
This is the first phase in which the colored quills come through and define their markings. This phase lasts about two days.
Four weeks of age
During this phase the color of the quills becomes more intense and they become less bendy. This phase lasts about three days.
Six weeks of age
In this phase the quills get sharper on the ends and visibly longer. The color intensifies again. The phase lasts between three and six days.
Eight weeks of age
This is the last phase in which the color intensifies again, making is easy to define their color and markings of the animal. The quills get really sharp on the ends and this phase can be so extreme that some hoglets tend to get bald patches. The phase lasts about a week, but can last longer and can overlap the next phase.
Twelve weeks of age
In this phase the quills become less sharp again, but will get stronger and even less bendy. The quills on the forehead get their final length and are visibly longer than the quills on the rest of the body. The color stays about the same and the phase last just a few days.
Six to eight months of age
In this phase the color intensity degrades again. The length of the phase varies from a week up to two months. This is the last quilling phase they will go through and they quill very steadily.
After these quilling phases an African Pygmy Hedgehog sheds about two to five quills a month and the color degrades as they get older. If the hedgehog has a darkening factor (Umbrous or also called Algerian) the color can stay about the same after the last quilling.
The quills start from a hair follicle which keeps the quill hanging under the skin. From the hair follicle the quill starts blunt and runs slightly spherical to the middle. After that it goes down to the sharp end of the quill. The tip, which includes the last 3 to 6 mm, is slightly bent. This way their companion in mating (or pet owners) wil have no issues regarding the quills. The quills will lay flat and the tip will point down. However when they are in danger, the quills can be set up and the bended tip of the quill will point upwards and bring damage to the attacker. The position of the quills are determined by two parallel muscles which run from the forehead between the ears to the back end. These muscles are called the dorsal muscles. When a hedgehog relaxes these muscles the quill lay flat. When the hedgehog tightens the muscles the quills will rise up.
At birth the quills are only a few mm long and there is no distinction between the quills in length. As the hedgehog grows older and becomes an adult, the quills get longer and the difference in length of the quills in their skirt, on their back and on the forehead become clearer. At adult age the quills in the skirt are the shortest (the line where the quills end and the fur begins): some of them are only 8 mm long. On the back the average is between 12 and 15 mm long and on the forehead they can grow to be 28 mm long! These forehead quills are used in the wild to bring damage to their prey. Small snakes can easily be punctured and killed before being eaten.
Air cushions and shafts
In the hair follicles are tiny air cushions. These are microscopic in size but do have a very important function. They prevent quills pushing into the skin and hedgehogs being damaged internally when under pressure. When a hedgehog falls off a big height or gets attacked by a predator, the air in these cushions gets divided into the eight air shafts that are located in the quills over the entire length of them. This way the quills stay in place and the hedgehog is less prone to damages and can continue on after the attack. The quills themselves are a bit bendy and this combination functions like a trampoline effect.
African Pygmy Hedgehogs have two front and two back legs. The front legs count five toes, whereas where the back legs count only four. This is also why they are sometimes called “Four-toed hedgehogs”. The toes have small, see-through nails where you can clearly see the blood flow. The paws have soft, pink foot beds which can’t produce calluses. This is because of the soft bedding in their natural habitat. The foot beds are bald, but do have a bit of fur on the top.
The anatomy of African Pygmy Hedgehogs does not only exist of the outside but also what beneath the skin. The skeleton and organs also belong within the term. We can’t talk you through everything but we can talk about the most notable aspects.
Above, you can see a schematic drawing of the skeleton of a European hedgehog. Despite a few small differences, the species are almost the same. African Pygmy Hedgehogs have 36 teeth and molars, of which the front four teeth are longer than the others. They can kill small prey in one single bite with these teeth. Their neck is short, which makes it possible to stay a long time in their curled position without doing damage to their bodies. Difference than other hedgehog species, the African Pygmy Hedgehogs has four toes on their back legs instead of five.
African Pygmy Hedgehogs are opportunistic insectivores. This means that they mainly eat insects but also small prey like birds and small rodents. They very rarely eat green leaves and fruits. This is because there is not always enough food to find and they sometimes have to settle for other nutrients to stay alive.
Due to their predisposition as insectivores, their digestive system is very short. Animal nutrients are easy to digest and don’t need a long way. From their stomach, the food runs to the small intestine and straight to the colon, rectum and leaves the body through the anus. African Pygmy Hedgehogs do not have a cecum. It is possible that this is due to their lack of feeding on vegetable food, but researches are not too sure on this.
The small intestines is about 1,5 times longer than the colon. This is because of the fact that the small intestine already digests nearly all nutrients and the colon does not need to do as much.
African Pygmy Hedgehog have kind of a sixth sense. The Jacobson organ makes sure that new scents get included and processed in the brain. The organ is placed between the palate and the nasal cavity. If the hedgehog sniffs up a new scent, the organ gets a signal and a large amount of saliva is released. This rinses through the organ and when the brains registered the scent, the hedgehog lubricates it over its body. The lubricating or “anointing” is done to empty and clean the organ for the next new scent. Why they specifically lubricate this on their own body is unknown.