A mystery shell

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Oct 15, 2011
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258
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.

 

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hmmmm, i posted two comments in here and neither one have appeared?

again for the third time.....i wasnt ignoring you i had a crazy busy week of exams when you posted.

Its hard to say for sure if that was an octopus or not. the hole looks more like the ones i have seen from octos, so its a definite possibility. the edges being beat up the way they are i think seems more like damage from the shell rolling around, but i'm not positive on that.
 
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CaptFish;185248 said:
hmmmm, i posted two comments in here and neither one have appeared?

again for the third time.....i wasnt ignoring you i had a crazy busy week of exams when you posted.

Its hard to say for sure if that was an octopus or not. the hole looks more like the ones i have seen from octos, so its a definite possibility. the edges being beat up the way they are i think seems more like damage from the shell rolling around, but i'm not positive on that.

I posted on this thread too, but mine was a couple days ago I think. Thats odd, has TONMO had vanishing posts before?
 
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hmm... no, and it's not showing up in the moderator logs as having been deleted. That's a strange one - be vigilant and let me know if you experience any further site weirdness! :goofysca:
 
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of course! Oh. Actually since my question never appeared it is a bit late but Ill ask anyways. Where did you find this shell? I've seen something resembling this from the North Myrtle Beach.
 
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ieatfalalfel;185259 said:
Where did you find this shell?.
Actually I believe I may have gotten this of the coast from VA Beach, not Myrtle Beach. I may be wrong, I barely had any time to think about this (this weekend hit me hard too, your not alone Capt Fish, not to mention I also got my nose crushed. Don't ask how). Don't know if I found under the water or in the more dryer area of the beach (implying that it may older and been through a lot of damage or the other way around). Whatever, any shell that washes up on a beach has usually been through some kind of damage wouldn't it? Is the Atlantic Ocean mainly composed of shallow mud grounds or a vast deep ocean sea? It may be just the fact that all the octopuses that I come across happen to be from the Pacific or somewhere that's not at the Atlantic Ocean. But, it seems that the only kinds of octopi that I could come up on the top of my head that dwells in the Atlantic would be a few pygmy octopus and blanket octopus. It would take quite a large octopus to make a hole this big wouldn't it? Octo beaks aren't that big.
 
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I think both shells have been carried through out the ocean from the Gulf Stream that may possibly say that it came from Caribbean waters. :shock: Now the Central Atlantic currents stir in a circular path stretching from the U.S. all the way to the opposite side of the Ocean. This may increase the probability that the shell came from somewhere else, don't get too excited.
 
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Update---

Atlantic Octopus Species Search 1#

Now that I've gotten the current stuff all sorted out, I've also looked up species of Octopus that inhabit Eastern U.S. shores that neighbor the Atlantic Ocean. There are two species that I've found so far, the Atlantic Ocean doesn't carry such a large Wildlife diversity as the Pacific so I didn't get many results.

Octopus Vulgaris-----------Common Octopus

Octopus Macropus---------Grass Octopus

I will keep researching further into this subject if I have more time, this may be the first. But it is not the last.
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Edit: Also, I forgot to mention a few more Octopus Species the may be a potential.

Octopus joubini-----Atlantic Pygmy Octopus (They also inhabit Caribbean waters as well)

Tremoctopus violaceus----Blanket Octopus ( This species does not however inhabit shores, but it does inhabit the open ocean)
 
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Humm, I am not 100% sure on this but it is my understanding that the marcropus in this hemisphere is found mostly in the gulf around Mexico and not along the Eastern Seaboard. Looking it up in Norman's Cephalopods A World Guide. It mentions the Atlantic but then goes on to call it a Caribbean octopus. The diver sitings I have seen are all from Mexican waters.
 
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We looked at 649 middens from 39 O. vulgaris dens in Bonaire. 60% of the gastropod shells were drilled. The holes were tiny and beveled, easy to miss unless you looked very closely. My guess is that drilling takes a lot of time and that other methods will be used first, if possible. For example, a lot of the bivalves were simply pulled apart - something a moon snail would not easily be able to do. Octopuses generally drill just a single hole in a strategic location near the adductor muscle. It has been a while but I think there were a few rare cases when more than one hole had been attempted - Dr. Roland Anderson would know for sure.

Aquarists captive rearing octopuses have a unique opportunity to try some novel experiments involving drilling in octopuses. I'd be happy to help advise. For example, do octopuses that have never encountered gastropods know where to drill or is this learned? Anyone with an octopus can look at: What is the food handeling time needed to drill through diff thicknesses of shells? An uw hydrophone would be a useful tool and should pick up the drilling sound. Am I right that drilling is not a preferred method to get a meal? Or do other factors come into play - such as the fact that drilling can be done back in the security of the octopuses lair. . .

James

By the way, the really interesting discovery in the work below was that while O. vulgaris as a group eat a diversity of prey, but individual octopuses often specialize.

Reference:

Octopus vulgaris in the Caribbean is a specializing generalist

Anderson, Wood, and Mather

ABSTRACT: The diet of Octopus vulgaris was determined from the remains of 649 prey items gathered from the middens of 38 dens in a small area off the Caribbean island of Bonaire. Remains of 35 species of gastropod (19% of the total), 19 bivalves (51%) and 21 crustaceans (30%) were identified and examined for mode of entry into hard-shelled prey. Although 60% of the gastropods were drilled, neither the size/weight ratio nor the presence of an operculum determined whether drilling occurred. There were strong differences in prey preference among individual octopuses, and the Cardona niche breadth index (B’) of the midden items was 0.08, indicative of specialization. Examples include the exclusive preference for Pinna carnea by one den occupant. This study, by focusing on assessment of preference at specific den locations, is the first to show that while the population had a wide choice of prey items, the individual choices were much narrower, indicating that octopuses were specializing generalists.
 
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NONE of mine have ever drilled offered clams, mussels or oysters. The oysters were left untouched (and are so messy when I open them that I no longer offer them), the clams are eventually forced open. Often the clams I put in the tanks survive several octopuses as the easier food is usually preferred. The only octopus I have had that will wipe a tank clean of all shelled creatures has been Little Bit (who is either a very small vulgaris or a very large joubini). She has been noticably stronger than the hummelinckis, briareus, macropus, mercatoris (who I don't think ever opened a clam), Abdopus (unsure of species) and bimac I have kept.
 
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NONE of mine have ever drilled offered clams, mussels or oysters

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?
 
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