Echidna: Spines

Ten Things I Like About... Podcast

Summary: Ouch! Echidna spines are no joke! Join Kiersten as she discusses this amazing echidna anatomy.

For my hearing impaired listeners, a complete transcript of this podcast follows the show notes on Podbean

Show Notes:

Short-beaked Echidna (Tachyglossus aculeates) Fact Sheet: Physical Characteristics, San Diego Wildlife Alliance Library. https://iecl.libguides.com

“Observations on Fur Development in Echidna (Monotremata, Mammalia) Indicate the Spines Precede Hairs in Ontogeny,” by Lorenzo Alibardi, and George Rogers. The Anatomical Record, Vol 298, Issue4, p. 761-770.

https://doi.org/10.1002/ar.23081

Music written and performed by Katherine Camp

Transcript

(Piano music plays)

Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife.

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Welcome to Ten Things I Like About… I’m Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we’ll find right out side our doors and some are continents away but all are fascinating.

This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won’t regret it.

This episode continues echidnas and the sixth thing I like about them is their spines. Last episode we talked about how they defend themselves from the very few predators they have and one of those defense mechanisms was the spines they have on their backs. Today we’re going to take a closer look at these spines and find out what exactly they are and how they work.

All four species of echidnas have spines. You may be asking what exactly is a spine, and this is a great question, listeners. You actually have spines all over your body right now! Not exactly, but spines are modified hairs. They are made out of keratin just like all mammalian hair, including human hair and nails.

Spines grow out of the skin just like thin hairs. So spines are made up of a medulla, which is the innermost layer of hair. It’s the softest and most fragile layer and functions as the marrow of the hair. The medulla is surrounded by a cortex. This is the thickest layer of a hair and contains most of the pigment, when hair has pigment. The outermost layer is the cuticle which is made up of dead cells. This is also the same anatomy of the softer hairs most mammals carry, including the echidna.

Underneath the skin the canal that the spines grow out of holds a thick inner root sheath made of cornified cells which surround the growing shaft. This shaft will eventually exit the skin with a sharp, pointed end and grow into the spine.

Echidnas grow spines on the dorsal, that’s the top, and the lateral, that’s the sides of the body. The number of spines taper off toward the underside of the echidna where you find only softer hairs. Echidnas do have softer hairs on their back and sides, as well as the spines giving them a slightly fuzzy appearance. Echidna spines will vary in size depending on where they are on the body. Some will be longer and some will be shorter so they fit nicely along the body.

The spines of echidnas have long roots that are embedded in a special layer of muscle. This layer of muscle allows the echidna to move each spine individually. Could you imagine be able to move the hairs on your body individually? That would be so cool!

This of course aides the echidna in using its spines to protect itself from harm. The spines can be moved individually or as a group depending on what the echidna is doing.

When used for protection against a predator, the idea is that the predators will get a nose or mouth full of sharp spines that will hopefully make them think twice about trying to continue eating this echidna. You may be thinking of another animal that does the same thing with quills, the North American porcupine. They use their quills to defend themselves just like the echidna with one little difference. When a North American porcupine encounters a predator they will back into the predator’s muzzle or whatever portion of their body that is exposed and the porcupine’s quills will release and stick in the animal’s body part. Definitely gets their point across.

This is not what happens with the echidna. When a predator bites at or swipes at an echidna, their spines stay put. They are not hooked at the ends like the North American Porcupine’s quills and they are made to stay attached until they are naturally shed with age. The spines of an echidna can stay attached for years.

This may have brought up another question from my intelligent listeners. What is the difference between a quill and a spine? To be completely honest I can’t find a great answer to this question. I can tell you that spines are used to refer to a broader group of modified hairs where quills are a specific type of spine. You often hear the term quill used when talking about porcupines. When doing research for this podcast all the sources I referenced said echidnas have spines.

In a scientific paper published in 2014 titled “Observations on Fur Development in Echidna” the authors question whether spines are actually modified hairs. They looked at various ages of preserved specimens of baby echidnas to determine if the spines grew from modified hair follicles or different follicles altogether. Turns out they form from different follicles than those of hair, so maybe the spines are not modified hairs at all, but something unique to itself.

It will be interesting to see what further research reveals.

Thanks for joining me for this pointed discussion of echidna spines because it’s my sixth favorite thing about this amazing monotreme.

If you're enjoying this podcast please recommend me to friends and family and take a moment to give me a rating on whatever platform your listening. It will help me reach more listeners and give the animals I talk about an even better chance at change.

Join me next week for another episode about echidnas.

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This has been an episode of Ten Things I like About with Kiersten and Company. Original music written and performed by Katherine Camp, piano extraordinaire.