Friday, October 3, 2008

Bone crushers




I mentioned last week that hyenas have a trick up their sleeve that allows them to take advantage of a food source that is inaccessible to most animals. A few people posted comments right away and hit the nail on the head. Hyenas are actually capable of breaking bones into smaller pieces and eating them. They accomplish this by gripping the bone between their teeth and the then biting down with immense amount of force. After splitting the bone into smaller fragments, they simply gulp down the chunks of bone.


The advantage of eating bones is more obvious during periods when prey animals are scarce. Being able to crack open, swallow and digest bones gives hyenas access to nutrients such as calcium and phosphorus. I would consider this similar to digging to the bottom of the pantry or freezer when I haven't been to the grocery store for a long time. I am not going to find my favorite food in either place, but I will find something to eat in one of those places. Mothers nursing cubs may eat bones to get large amounts of calcium for milk production.


A couple of interesting side notes on the diet of a spotted hyena. Spotted hyenas get around 95% of their annual food intake from fresh ungulate kills. Eating bones can be an important supplement to a healthy diet, but eating fresh meat is of paramount importance. Reports exist of hyenas cracking and eating bones as large as giraffe femurs.In the photo below, James is holding three giraffe leg bones for perspective on the size of the bones. James is about five feet and nine inches tall, so that should give you some idea about the size of these bones and the strength of hyena jaws.


Most hyenas favor cracking bones on either the right or left side of their mouth. Instead of being right or left-handed, they are right or left-mouthed. Many animals worldwide exhibit some form of favoritism for one side over the other. There is only one other animal to my knowledge that regularly breaks open bones to eat the marrow, and that is the Lammergeier, also know as the bearded vulture. This vulture picks up bones in its mouth and flies into the sky. They then release the bones and drop them on rocks with the hope of breaking open the bone. It may take several tries before the bone actually breaks open, if it does at all. Much less efficient than the hyena method of using their massive jaw muscles to break open the bones



7 comments:

Katy said...

Good photo of James. Tell him I said hi :)

Will said...

I bet hyenas aren't nearly as good at flying as vultures, though. To each their own specialization.

Robin M. Weare said...

Have you observed if "right-mouthers" tend to outnumber "left-mouthers" or the reverse? I've read that with domestic cats, what few cats show a preference for using one paw over the other seem to be "left-handed".

Andy Flies said...

Robin,
I posed your question to Jamie Tanner. She recently completed her Ph.D. and did the research on right/left-jawed hyenas. She said it is a pretty even mix for right vs. left. I know there are quite a few animals that favor one side over the other. Some whales even prefer turning to one side I believe, you can check that out if you like.

Will,
Hyenas are certainly not good at flying. I am a huge fan of vultures and I am keeping open the possibility of studying their immune systems in the future.

Thanks for the comments.

Andy Flies said...
This comment has been removed by the author.
Anonymous said...

Andy, what is the nastiest thing you've seen them eat and said to yourself "I can't believe they are not going to get sick?"

-Jeff

Robin M. Weare said...

Andy -- thank you for the reply. I'd heard an animal has to be very intelligent indeed to have "handedness", so it is interesting to me that domestic cats show it to a small degree while spotted hyenas seem to have none.


Michigan State University | College of Natural Science