Why is there no animal that can eat vertebrates' bones?

[Dervorin]

Lammergeiers are known to drop bones to shatter them and then eat the fragments.

And just how would you go about eating an invertebrate’s bones?

[Blake]

[QUOTE=Lemur866]
Bones contain both minerals and protein. Once the protein is gone you can’t get anything more than minerals from what’s left over.
[/QUOTE]

Actually most of the calories in bone are on the form of fat. The marrow is one of the purets forms of fat on an animal carcass.

[QUOTE=OtakuLoki]
Just out of curiousity - how much of the shape of the bone is due to the structure imparted by the proteins?
[/quote]

All of it. The protein is laid down first and the calcium is then attached to the protein, rather like hanging papier mache over a wire frame. The wire gives the shape and the mache just fills in the spaces.

You can if you want soak a boine in a dilute acid solution for a week to remove all the calcium and then remove what looks like the original bone, except that you can now tie it in knots. Removing the calicum has no effect at all on the shpe of the bone.

What I mean, it seems to me that if bones are calcium heavy protein matrices, as long as there’s a recognizable shape, there’s bound to be still some protein fractions available there.

Depends what’s happened to it. If the bone has been enzymatically digested then proteins will all have been solubilised and stipped away. That leaves the clacium matrix with zero protein, essentially the reverse of what happens if you acid treat a bone. Same shape, no protein.

[QUOTE=smiling bandit]
The protein is mostly in the marrow, not the bone tissue itself. The bone tissue has very few, if any, calories to extract.
[/QUOTE]

The protein is mostly in the bone, the marrow contains a sizable amount of pratein but its mostly fat and occupies relatively little of the bone volume. In addition the bone contains blood vesslels , fats and other miscellaneous inclusions. Bone as a tissue consequently has quite a few calories, although they can be hard to extract.

As for the OP, your undertsanding is all wrong. Lots of animals, like devils, eat bones, and they don’t pas through undigested. If that were the case why would they bother to swallow them? The bones are digested and all the usable nutrients are extracted. The useless stuff is then excreted. This is no different to what humans do when eating corn, and you wouldn’t claim that humans don’t digest corn.

[Spoke]

[QUOTE=Schuyler]
Try a Google search with “whale bones monterey” for articles and pictures of worms that are devouring the bones of a deceased whale - here’s an example article: “Whale carcass yields bone-devouring worms”
[/QUOTE]

What freaky critters:

The scientists were initially puzzled by the fact that all the worms they collected were females. However, while examining the two- to seven-centimeter-long female worms under a microscope, they discovered that most females had dozens of microscopic male worms living within their bodies. These male worms looked as if they had never developed past their larval stage—their bodies still contained bits of yolk—but they also contained copious quantities of sperm.

[Contrapuntal]

[QUOTE=Schuyler]
Try a Google search with “whale bones monterey” for articles and pictures of worms that are devouring the bones of a deceased whale - here’s an example article: “Whale carcass yields bone-devouring worms”
[/QUOTE]
Why do you suppose they only whale bones? How can the researchers be sure of that?

[Blake]

[QUOTE=Contrapuntal]
Why do you suppose they only whale bones? How can the researchers be sure of that?
[/QUOTE]

Nobody is caiming they only eat whale bones, the claim is that they have only ever been found eating whale bones. However they are so specialised that the only niche they could concievably fill is that of eating bones. Where else are you going to find a large, solid, protective, lipid filled structure in the deep ocean? These animals need exactly those conditions to reproduce. It is entirely plausible that they also consume the bones of other large marine organisms such as very large fish or seals, in fact it’s hard to see why they would not, but whlae carcasses are probably the most common food source in the regions they inhabit.

[MrDibble]

There’s actually a term for such blubber-from-heaven - Whale Fall

[Ale]

[QUOTE=OtakuLoki]
Another contrarian datapoint: There were no remains found with, on nor near the wreck of the Titanic. Nor associated with other bathyspheric wrecks that have been investigated since then: Bismark, Hood, the Midway ships. My gut reaction is that something had to have eaten them, but I don’t think that there’s any evidence for what that mechanism may have been.

BTW: Great Dave, unless I’m misremembering it, my copy of Young’s Mammology does claim that Hyenas take nutrition from the bones themselves, not just the tissues in the bone. I’ll dig it out to check.
[/QUOTE]

The bones probably dissolved over the many decades since the sinking…

After googling a little bit I found this tidbit from Robert Ballard himself:

I do know that in the deep sea bones actually dissolved so I would not expect to find them there.

[Do_Not_Taunt]

[QUOTE=Blake]
This is no different to what humans do when eating corn, and you wouldn’t claim that humans don’t digest corn.
[/QUOTE]
Why can’t you digest corn?

I get the point you’re making, but people do make this very claim about whole kernels of corn (no one claims you can’t digest processed corn.)