A mystery shell

[Cuddlycuttlefsh]

So, very once in a while I get a chance to go to near the shore on the eastern coast. I got a chance to collect this particular shell at Myrtle Beach. I've seen this is what is left after an octopus has drilled into clams, scallops, etc when they can't pry it open. What do you think, what are your thoughts on this shell, I'm really excited to see whether this shell WAS really the remains of a victim of octopus shell drilling. About 1" long in length and the hole is located in the back part of the shell. The diameter of the hole is about a millimeter and a half.

 

[Terri]

Bromley, R. G., 1993, Predation habits of octopus past and present and a new ichnospecies, Oichnus ovalis. Bull. geol. Soc. Denmark 40:167-173 pdf here Fossil drill holes

Excellent paper, I wouldn't have ever thought I would have such a fascination for "drill holes" old or new.

 

[ceph]

D, I'm way out of my element here, but is it possible they are not drilling because they're living in captivity and don't have to work as hard for their food as they might have to in the wild?

Not only possible, but likely. It may be that even in the wild they switch to easier to access food when they can. Drilling takes time and effort, pulling a bivalve apart is much quicker and something they are very good at. Anderson did some work on the amount of force an octopus can exert - they are strong suckers!

I would also expect differences between species and individuals in their propensity to drill.

Finally, keep in mind that the drill holes are very small. We didn't see many of them until we started seriously looking.

 

[Cuddlycuttlefsh]

Do the drill holes go much smaller than the millimeters, I'm thinking about reconsidering the size of this drill hole. Possibly massive in comparison to what we're talking about in this thread. And are there any remnants and traces of the fluids injected into the gastropod left behind such as some are injected to eradicate the calcium in the protective shell that one can look for?

@ post 27

I appreciate you a lot for putting the abstract on the bottom, you saved me loads of trouble

 

[ceph]

On the order of a mm at the surface - slightly larger for thicker shells. Just a pin prick at the other side of the beveled hole - all it needs to be is big enough to squirt in some special sauce from the salivary gland.

If you want to get at the secret sauce, the best way would be to go directly to a salivary gland in an octopus. This is likely to be terminal for the octopus and not the type of research I generally engage in. Others do and it is valuable and important work; there are likely many biologically active compounds in the mix and some may have medical and other uses.

I'm not sure what traces would be left after a gastropod has been injected and released its grip for the last time. Besides, I don't think the protective shell or CaC03 is a problem once the gastropod is no longer able to hold the operculum (door) closed. It is game over at that point.

They may have some chemical help vs the shell as they actively drill it. We seem to need a biochemist today. . .

James

PS Thanks for the thanks

 

[Terri]

Possibly massive in comparison to what we're talking about in this thread

They do seem a little large, back to post #9?

 

[Cuddlycuttlefsh]

We seem to need a biochemist today. . .

James

PS Thanks for the thanks

Twice!

@ Terri- They do seem quite large though

 

[DWhatley]

... is it possible they are not drilling because they're living in captivity and don't have to work as hard for their food as they might have to in the wild?

Terri,
As Ceph said, absolutely (and is my guess why some clams are left alone through several octopuses before becoming a meal. Also, as Ceph mentioned, species as well as age would also play a part in both strength and the existence of a radula.

 

[Terri]

Twice!

LOL, cross posted at exactly the same moment with Ceph, started to delete my post but left it alone.

 

[Terri]

Also, as Ceph mentioned, species as well as age would also play a part in both strength and the existence of a radula.

Interesting, I just assumed all octopus had radula.

 

[DWhatley]

It is my understanding that some do not have radula but these may be of the little known deep water variety.

 

[ieatfalalfel]

Are there no clams and such to drill into deep water?

 

[DWhatley]

I don't know much about the deep water critters but some of them (at least squid) stay pelagic. The blanket octopus is one that does not often come to shallower waters but we have recently seen some very good photos and video of one spotted in the Keys that was digging in the sand (a big surprise) so that species, at least, is very likely to eat clams and have a radula. I am not sure where I read (I am thinking something Steve wrote) that some do not have them though nor do I know which species are included.

 

[Cuddlycuttlefsh]

Not sure if it may be deep water species but I have a stronger feeling either it's something else (not an octopus) or its one of the bigger species such as Vulgaris and Blanket Octopus. Caribbean reef Octopus can get big don't they? I'd surely add them to my suspect list.