Apple #565: Elephant Feet

Way back before Christmas, I was watching a documentary about elephants.  The elephants were walking along in their slow, rhythmic way, and I was noticing their feet.  When they stepped on the ground, their feet seemed to squash outward, like there was a cushion built in there.  Of course an elephant's feet have to support a lot of weight, so I thought maybe they're built in some special way that gives them extra support. The more I thought about it, the more I wanted to know, how is an elephant's foot put together.

Here is a brief video of an elephant walking to show you a little bit of what I was looking at. Watch the back feet of this young elephant to see most clearly how the feet sort of squash outward with each step.

• It turns out, elephant feet do come equipped with an interior cushion.

• The way elephant feet are built, the animals are essentially walking on their tip-toes the entire time.

  
This is what the bones of an Asian elephant's back foot look like. If you put your hand tent-like on a table so that only the tips of your fingers touched the table, you'd have a good representation in front of you.
(Photo from Elephants Encyclopedia)

• A cushion of "fibrous connective tissue" and "adipose tissue" (which means fat), along with collagen and various other protein-like substances acts as a cushion that sits between the bones of the foot and the outer skin.

 
This diagram shows the position of the bones within an elephant's foot. The gray shaded area represents where the cushion of fatty tissue and cartilage supports the bones.  To see a full-color artistic depiction of the same idea, check out Margaret Meintjes' print (she won't allow any reproduction of her image whatsoever or I'd show it to you here)
(Diagram from The structure of the cushions in the feet of African elephants, Weissengruber et al., Journal of Anatomy, December 2006)

• The fibers within the fatty tissue give the cushion a little more substance and structure than it would have otherwise. This is one of the things about an elephant's foot that helps it to grip the ground better.

• The cushion is also why elephants walk so softly -- which is pretty remarkable given what enormous animals they are.

Here is a whole family of elephants walking past the jeep of the person taking the video. The noise of the wind blowing is louder than the footsteps of the elephants. (By the way, that's Serengeti.)

• Another thing that gives an elephant's foot traction is the channels or "tracts" on the bottom of their feet.

The bottom of a healthy elephant's foot. Tracts like these that are clean and distinct help an elephant to maintain traction on slippery ground. And yes, this is the photo from my latest teaser.
(Photo from The Elephant Sanctuary in Tennessee)

• Since elephants also use their feet to push aside vegetation and dirt to make their "sleeping spots," the tracts turn out to be helpful in excavation, too.

• Elephants have toenails, too, except they're technically not toenails because they're not connected in any direct way to the toes.  The bones of the toe are buried deep within the foot, and the "nails" live independently on the outside of the foot.  The nails are more like protective shields for the front of the foot. "Cornified nails" is the way one site described them.

Elephant "toenails" technically aren't toenails.
(Photo from Elephant Information Repository)

• Like humans' toenails, elephants need to have their toenails trimmed periodically.  In the wild, all the walking around and digging they do along with the mud baths they give themselves--all that activity helps to keep their toenails worn to so that they're even with the bottom of their feet, their tracts stay clean, and the cushion stays tihck and healthy.

• In captivity, however, elephants don't move around or "excavate" as much.  Because their feet don't get the kind of use they need in order to stay healthy, they tend to have a lot of foot problems.  In fact, 50% of elephant health problems in captivity are related to their feet.  So elephant foot care becomes extremely important.  Lots of sites online have all sorts of instructions about how to give elephants baths and, in particular, how to wash and care for their feet.

• Apparently, it's much easier to trim an elephant's toenails if the foot is warm and still damp from a bath.

 
This is how an elephant gets a pedicure -- with an iron rasp.
(Photo from the Elephant Encyclopedia)


These keepers at the Dublin Zoo are doing it the way you're supposed to:  give the elephant a bath first, then trim the toenails and, yes, trim the bottom of the foot too.  Trimming keeps the tracts clean and healthy.

• Two more interesting tidbits about elephant feet:

• There are all kinds of variations among elephants in terms of toes and nails. In general, African elephants have 4 toenails on their front feet and 3 on the back, while Asian elephants have 5 on the front feet and 4 on the back. But these numbers aren't true for all elephants. In fact, some elephants have 0 nails on one or more feet. Why this is so, no one is quite sure, except that it might be part of the variations within the species.

• Bulls make different footprints than females. Bull elephants place their back feet just to the side of where the front feet fall, so their footprints usually show two rounded or ovoid prints side by side.  Females, however, place their back feet in exactly the same spot as the front.

OK, one last video. This shows Raja (pronounced Rai-ya) getting her nails filed. I don't think the keeper has washed her feet first so this is probably not the best way to do it. But what I like about this video is how Raja keeps sneaking her trunk out through the bars, trying to get more of those carrots.




Sources
Weissengruber et al., The structure of the cushions in the feet of African elephants, Journal of Anatomy, December 2006, 781-792.
Elephant Information Repository, The Feet
Elephants Encyclopedia, Elephant Feet, Trimming Elephant Feet
Elephant Encyclopedia, Feet Hoof Care
The Elephant Sanctuary in Tennessee, African Ele-Diary 2004 
Carol Buckley, Captive Elephant Footcare: Natural-Habitat Husbandry Techniques
Remote Animal Monitoring Solutions, Thermography of the Elephant Foot