Dead Bowhead whale says "Ouch"

Where exactly in the column is the fusion? My impression is that in normal swimming there is more flexion at some locations than at others (the "ball vertebra" near the base of the leading edge of the flukes being perhaps the site of greatest flexion).
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At a guess, with a bit of luck a whale could survive for a considerable period with seriously impaired swimming: how often does a bowhead swim at maximum speed? (Rorqual-style lunge-feeding ought to make heavier demands on the swimming apparatus than Balaenid-style skim feeding (though this is also a guess).)

Balaena mysticetus is the bowhead; B. glacialis is the great right whale. One or the other must be incorrect in this post.

Oops, it's labelled 'Baleine Franche Balaena mysticetus'; I just made a silly error. Thanks.

Could it be trauma from a harpoon strike?

Harpoon, orca...some weird autoimmune thing...gout...

I know little about animal pathology and less about specifically cetacean pathology, so I'm speculating wildly here, but two thoughts do come to mind:

1) a swimming whale uses the entirety of its tail area, from roughly the pelvic area back. I think Allan Hazen is on to something: Damage like that shown might not handicap a slow-swimming whale like a right whale all that much.

2) if the hole was on the dorsal side of the vertebra, I'd have no problem labeling it the result of traumatic injury. However, a hole like that on the underside of the vertebra, coupled with the obvious calcification around it, makes me wonder is this is an example of some internal problem -- possibly arthritis, possibly some sort of bone infection, possibly even some weird kind of bone cancer.

Is anything known about the history of this animal? Particularly where, when, and how it was killed, and how old it was at the time?

My background is physics, not physiology, so this is just another inexpert wild stab: Both ancient mosasaurs and modern whales sometimes show evidence of decompression illness ("the bends")in the bones, particularly the vertebrae. I do know that bone necrosis is indeed a common result of severe or chronic-repeated decompression injuries, but I have no idea what it actually _looks_ like. Maybe like this in extreme cases???

Aside from anything else, the placement on the body (at the tail) would preclude it from being a harpoon strike. No whaler in their right mind would put a harpoon near a whale's tail, for a number of reasons: much smaller target, no vital organs, and (for hand-thrown harpoons, which wouldn't have enough force to punch a hole in the spinal column anyway), insanely dangerous.

Sven:

Harpoon, orca...some weird autoimmune thing...gout...

Ship collision...

(I find the 'harpoon' suggestion unlikely, for the reasons stated by Keith.)

I don´t think this is a result of a trauma, as I have seen similar cases of deformed vertebrae which fused together in human skeletons which had also similar "porosous" structures. In this cases it was a result of diseases. The vertebrae looks very porosus, not really like "healthy" callus growth. Perhpas I am wrong and this is really a result of a fracture, but to me it looks very much like the result of a disease. Some years ago I would have had still more knowledge about this... but you forget things you don´t need so easily.
At least I found some comparable pathologies in Mosasaur skeletons:
http://www.oceansofkansas.com/mosapath.html

Those are some serious intervertebral discs!

Perhaps the whale's pathology originated with a congenital defect of the vertebral column, such as spondylolisthesis, incomplete ossification, hemivertebra, or scoliosis. Many humans have such anomalies, particularly in the lumbosacral region, and may not be aware of them until they're older and develop painful back problems. I've read estimates that 5-10% of humans have a minor defect in a lumbar vertebral arch (IOW mild spina bifida); a small tuft of hair in the midline may mark the site.

Don't forget that every whale hunter starts somewhere. Maybe it was a harpoon shot by an idiot?

"Any idea what could have caused this incredible pathology?"

Cthulhu did it. The whale kept waking him up with his whalesong.

No whaler in their right mind would put a harpoon near a whale's tail, for a number of reasons: ...

Well, Keith, if the bone lesion is the result of a harpoon strike, the harpooner obviously missed his mark.

Upon reflection, I'm more inclined to think it's the result of impact by a ship's propeller. It's possible that it's due to some autonomous pathology but it sure looks like a traumatic injury to me.

No whaler in their right mind would put a harpoon near a whale's tail, for a number of reasons: ...

Well, Keith, if the ankylosis is the result of a harpoon strike, the harpooner obviously missed his mark.

Upon reflection, I'm more inclined to think it's the result of infection subsequent to impact by a ship's propeller. It's possible that it's due to some autonomous pathology but it sure looks like a traumatic injury to me.

Why would Cthulhu do it, Anon? Everyone knows that cetaceans worship Cthulhu.

Ooops. Didn't realize that the first version posted..

You know, I understand that it may seem erroneous that the hole came from a harpoon. However, in looking at the cannon-charged harpoons used, and the fact that you have some whaler shooting at the whale from a moving boat, I really don't know how effective these guys are when firing these harpoons. It is almost conceiveable that the shot, if it was indeed a shot, was a clean shot that went through the spine of the whale and kept going. Just an idea, mind you. Did you have a chance to examine the hole up close or was it too decayed to suggest such? You also do have idiots on naval boats that do shoot at whales. The Russians use smaller weapons like AKA 47's.

Actually, cases of pathologic or fused vertebrae in the anterior caudal and lumbar region is fairly common in cetaceans. Contrary to what is stated above, flexion/extension of the post-thoracic vertebral column is not evenly distributed in cetaceans, and most of the movement occurs in the lumbars and anterior caudals; one of the caudal vertebrae is even sub-spherical and acts as a nick-point. Anyway, a good proportion of mounted mysticete skeletons (and some fossil skeletons) exhibit fused posterior lumbars/anterior caudals.

Otherwise, as far as 'Balaena glacialis' is concerned - its in a different genus, Eubalaena.

Bobby

There are some problems with the harpoon hypothesis. If you you think about it, what was there before, fused vertebrae or oval hole in the bone, what do you think? If you assume it was a harpoon impact which caused massive damage on at least five vertebrae, it would have required a massive amount of energy. This alone excludes a hand-harpoon, as only a mechanical harpoon could (theoretically) cause such damage. The location of the pathology is actually no argument against a harpoon. Of course no whaler would prefer to shoot at a whale´s tail instead of more vulnerable parts of the body, but shooting from a swimming ship on something swimming in the water is undoubtly not always easy. There are also sometimes horrible yet not initially lethal injuries when hunters with guns don´t hit the planned body region but instead only the snout, limbs, the upside of the back, the downside of the belly or the backside. Similar things undoubtly happend during whale hunts too.
But to come back to the original issue, if it was a harpoon which could cause such massive bone fracture, why are the lateral projections of the fused vertebrae still in perfect arrangement? In general you assume a serious dislocation of the fragments. Furthermore, if you looks how enormous the callus growth is, it is hard too imagine that a hole caused by a harpoon would remain more or less in situ, but become mainly overgrown. If it would be overgrown, the original deffect would need to be even much greater, so there are even bigger problems when we keep in mind that there are no dislocations of lateral vertebral projections.

Don't forget that every whale hunter starts somewhere. Maybe it was a harpoon shot by an idiot?

I don't think a harpoon (or other projectile) could result in such a clean hole. Osteoclasts were at work.

A few quick comments. Yup, as Boesse says (comment 19) vertebral fusion is not unusual in cetaceans (I may do a follow-up article on this subject), but most fusions are 'tidy' and don't look anything like the gnarly mess shown above in this unfortunate bowhead (and I know nothing of its history or provenance, sorry). That hole looks reactive (perhaps where a sequestrum formed, eventually leading to chronic bone-thinning and eventual perforation) - I don't think it's likely that it's a wound caused by a harpoon.

Darren:

I know nothing of its history or provenance, sorry

Was there no information about this specimen at the museum?

How about some sort of large hook that penetrated and lodged, then slowly rusted away?
(BTW I view cetaceans and sirenians as "bipeds", as witnesses have seen newborn sea cows propel with their 2 fins as well as some sickly dolphins.)

An off-topic observation: Looks very similar to the pathologic caudal verts that you see quite frequently in sauropods...

As to where a harpooner would aim... Probably they aim at the whale: think about the ratio of hitsw\ to shells fired at, say, the Battle of Jutland and remember that battleships are much bigger than whales and move in a more predictable manner!

O.k., the range is typically a lot closer, so suppose that the harpooner does aim for a particular part of the whale. Where? Well, obviously, the part that's above water when the harpooner is in a position to shoot.

Where would he WANT to aim if he was lucky and everything lined up in the best (for the harpooner) possible way? Aim at the chest and he MIGHT hit the heart and kill the whale immediately... and then again he might not. (I don't know what the ratios are, but historically many whales have had to be struck more than once before they are killed. At least in 19th Century whaling, whale-boats carried different weapons for different stages of the hunt: barbed harpoons to attach a rope to the whale, barbless lances for administering the coup de grace to a whale exhausted from earlier struggle.) In the cases where a harpooned blue whale has towed the whale-catcher ship for hours (with the ship's engine running in reverse), the harpoon had struck well forward (shoulder region). If the harpoon strikes closer to the tail end the whale's body is stretched straight (by tension on the rope) when it tries to swim, and it can't struggle as long or as dramatically.

Conclusion: I have no idea whether the trauma occasioning this pathological condition was harpoon induced or not, but the fact that it is near the tail and not near the heart doesn't strike me as strong evidence that it wasn't.

Glancing through the literature, I noticed that spondylitis, which has been recorded in several cetacean species, would seem to cause just that kind of irregular bone growth around vertebrae (see, e.g., Félix et al., 2007). Infectious spondylitis may result from bacterial infection of physical wounds, but it could just as well result from bacteremia or urinary tract infection.

Reference:

Félix, F., Haase, B. & Aguirre, W.E. 2007. Spondylitis in a humpback whale (Megaptera novaeangliae) from the southeast Pacific. Diseases of Aquatic Organisms 75, 259â264.

Infectious spondylitis may result from bacterial infection of physical wounds..

There you have it, I'd say. What caused the wound? Ship's propeller, harpoon, shark bite? Who knows? Thanks, Dartian, for the Felix, et al., reference. I hadn't been aware that my old friend Windsor had published anything re: marine mammals. Now I see that he has, in both Spanish & English.

Thanks, Dartian, for the Felix, et al., reference.

You're welcome, Darwinsdog.

Regarding the question what, if any, effect such a vertebral deformation would have on a whale's fitness, Félix et al. suggest that it would be highly negative, possibly even life-threatening. Severe spondylitis impedes the whale's tail movements and slows down its swimming - and this, in turn, presumably makes the whale more vulnerable to infections by barnacles, whale lice, and other ectoparasites (the carcass of the young humpback whale the authors described in their 2007 paper was covered by 'uncharacteristically large numbers' of Cyamus whale lice).

Darren, were the pectoral fin bones and ligament attachment points noticeably unusual, as in hyper robust or strained?

Severe spondylitis impedes the whale's tail movements and.. presumably makes the whale more vulnerable to infections by.. ectoparasites..

Make's 'em incapable of or ineffective at breaching, which to my understanding is at least in part a behavioral adaptation that reduces ectoparasite infestations.

For what my 2p is worth I'm going to throw my hat in with Sordes. I'd suggest it's a baterial infection in, or around, the bone. It does remind me of the middle toe of Big Al, as well as some abnormal bone growth I saw in some pictures of pathologies during my taphonomic research. I seem to recall that one I saw was an infection in a broken rib. The rib refused at a funny angle with a large clump of pourous bone around the site of the infection.

I would look it up, but it's 2.30 am....