Article last updated on March 31st, 2019.
The build-up of quills and hairs in African Pygmy Hedgehogs
If you ever looked at an African Pygmy Hedgehog and wondered how those quills can withstand extreme pressure whenever they fall off the couch again, this post will explain a lot to you.
Due to being nocturnal, they have very poor eyesight. They don’t see well in night or by day and they trust mainly on their sense of smell and their great hearing abilities. These senses are very well developed due to their lack of sight. But even though they have developed better senses to compensate for their bad eyes, this doesn’t protect them from harm perse.
Predators might attack them and the quills are a great way for hedgehogs to defend themselves. Or whenever they fall down a tree trunk or from a pile of stones, their quills will save them from harm. But how does that work? That’s a very interesting question!
Dorsal muscles and hair follicles
Each and every quill is attatched to a hair follicle. These follicles are tiny sacks under the skin, that hold the quill in place so they don’t fall out. Allthough it’s not that firmly attatched that it does too much harm and doesn’t cause too much pain when a predator pulls out a few quills. The base of a quill that is attatched to the follicle is small, seethrough and very bendy. And it also has a slight curve. This curve is there for a very special reason.
Have you ever heard of the dorsal muscles? Those are the two muscles that go from the hedgehogs head all the way to their back. If you take a close look at their heads, you can see a small gap between the quills on the forehead. The two dorsal muscles start on each side of that gap. you will also see that the quills in that area are longer than on the rest of their bodies. The dorsal muscles are the muscles a hedgehog uses to ball up and protect itself. When these muscles are relaxed, the hedgehog is at ease and the quills will lie flat on their backs. But when they strain these muscles, they pull the longer quills over their heads to protect their vitals, as well as curling up their body -much like our human fetal position- until their entire body is covered in quills that are pointed outwards on all sides.
It is very important to know why and how the quills are placed into the skin, because if the quills were placed in the opposite direction, they wouldn’t be able to protect themselves.
Close-up of the quill pigments
A hedgehog’s quill has a slight ringed look, but not when you look at it under a microscope. The beginning of the quill already has a slight amount of pigment and is just an off-white color that gradually becomes stronger and more vibrant. Around the middle of the quill, the pigment is at its darkest and it very rapidly goes towards plain white towards the tip of the quill which is partially translucent and without any kind of pigment. The pigment can differ a lot per color of the hedgehog and with that, the build-up can also differt a slight bit. Since this has never been fully researched, we started a microscopic research towards the hedgehog colors aside from the genetic inheritation study we are conducting. You can help with this microscopic research by donating quills and (colored) hairs from their masks to us. Contact us for more information about this research.
These pictures are made from a Chocolate colored hedgehog to use as a first example.
Cross section of a quill
The quills of a hedgehog have a very complex structure to be able to bend and devide the pressure on a hedgehogs body. The very beginning of a quill -the part that’s placed in the hair follicle- is solid kerateen. But above that point, there’s a complex structure of 15 to 20 airshafts which each are devided into very small air bubbles in top of eachother. Very thin sheats of kerateen cover each air bubble to make it sturdy, but also very flexible so a quill doesn’t break under great pressure. They are not unbreakable, but deffinitally close!
In the middle of these bubbled airshafts, is an almost empty middle circle. Almost empty, because there are very thin and very small ropes of keratin that hold the airshaft together, adding up to even more strenght. Impressive, right?!
The hairs of an African Pygmy Hedgehog are not as complex as their quills, but they deffinately are just as fascinating. The part of the hair inside a hair follicle is round and mostly translucent. As the hairs become thicker they get more pigmented into the color of the hedgehog, in this case a dark brown color as excpected in a Chocolate colored hedgehog. The outside of a hair has coronal scales which are found in a lot of animal species. Every type of animal has a unique pattern of scales. We haven’t made a scale cast yet, but we will do that later and add it into this article. However, the scales are somewhite visible on the pictures as small uneven rings around the hair.