What is this bone?

October 17, 2006 2:13 PM

This bone was found on a Cape Cod, Massachusetts beach this week. It is about 3" tall and about 3" from tip to tip of the "horns." It looks like a vertebra of some type, but I can find no images of similar ones online. Any marine biologists out there care to tell me what kind of a bone it is? Other images inside.

posted by Rock Steady to science & nature (11 comments total)

It appears to me to be a part of the trunk vertebrae of a fish - similar to this configuration.
posted by ericb at 2:38 PM on October 17, 2006

Hope someone comes along with more knowledge. Like you, I can't seem to locate similar photographic evidence.
posted by ericb at 2:41 PM on October 17, 2006

I couldn't tell you what kind of fish it is -- I'm thinking it is a little too degraded to be able to say much about it. In the lower left of ericb's photo, that vertebra could very well be yours -- with the delicate top protrubrance broken off and worn smooth. I think you want to take into account, as you search online, that your bone is probably not intact.
posted by Methylviolet at 2:55 PM on October 17, 2006

A portion of a sea-monkey diadem?
posted by rob511 at 3:39 PM on October 17, 2006

Thanks guys. It does not appear to be broken at all, Methylviolet, and there are some pretty fine edges in some places that are not significantly worn down, but I suppose I could be wrong. The other thing is, (this is hard to describe in words) in ericb's image (and many of the other ones I saw online) the "fins" radiate directly outward from the central cylindrical section, whereas in this example, they are sort of swept-back (or -forwards). I'm pretty sure it is not like any of the bones in ericb's image.
posted by Rock Steady at 3:45 PM on October 17, 2006

Possible indirect help:

Finding it on the beach doesn't mean it's from a fish or marine mammal. It could just as easily have washed from a garbage barge or similar, and might be from a cow or horse or summat.
posted by ROU_Xenophobe at 4:28 PM on October 17, 2006

I think this vertebra is from a bony fish. Without going into too much detail, the key features are that it is concave at both ends. I can't tell from the pictures but I assume there's a small hole in the center.
I would agree that it's worn, but the two processes are (again, from what I can tell) the neural arch/spine (where the spinal cord would go through) and the hemal arch/spine. That means it's from a tail (caudal vertebra). Abdominal vertebrae have only the neural arch/spine.
From the size, I would guess striped bass or possibly bluefish.
posted by nekton at 4:55 PM on October 17, 2006 [1 favorite]

I showed this picture to a colleague down the hall who identifies bones for a living (dietary studies of sea mammals via stomach contents and archaeological bones) -- she is one of the top people in the world for such work. She says it is a vertebra from a fish, almost certainly of the Scombridae family -- this group of fishes includes Tuna, mackerel and bonito. She has a secondary suggestion of either swordfish who belong to a separate family all on their own, or marlin. All are families within the order Perciformes, which encompasses many, many fish. Likely you could narrow this down by thinking what fish are present or common off Cape Cod.

Compare it to this bluefin tuna vertebra (low resolution pic from my colleague's website) If you squint at this picture you can see it's probably from very close to the tail assembly of the fish as the flanges become flatter and fit closer to the vertebral centrae.

She can't say for sure since we don't have many comparative specimens of Atlantic ocean taxa. Based on size its a large fish and tuna is perhaps the most likely. The flanges act to lock together the vertebrae and provide rigidity useful for powerful predatory swimmers. Tuna vibrate their tails at a very high frequency, a trick that is aided by powerfully compressing a very rigid spiny column -- they don't really "wag" their tails like you might think.

Anyway, it is definitely a vertebrae from a very large fish - at three inches long for a vert, estimate >100 pounds.
posted by Rumple at 5:56 PM on October 17, 2006 [3 favorites]

More on the locked-spine swimming mechanics here
posted by Rumple at 6:31 PM on October 17, 2006

this group of fishes includes Tuna

BTW -- tuna fishing is popular off of Cape Cod -- recreational and commercial -- particularly near/adjacent to Georges Bank and Stellwagen Bank.
posted by ericb at 7:22 PM on October 17, 2006

Cool bone. Definitely a vertebra.
posted by owl at 9:32 AM on October 18, 2006