What's The Predator That Drills Holes On Bivalves?

[steve p.]

I've noticed drill holes on many of the fossil bivalves from the Stone City Formation near Bryan, Tx.

From what I read, the Moon shells (Naticidae) and the Rock shells (Murex) make drill holes in their prey.

Since so many bivalves have drill holes, surely the predator is represented in the fossil mix.

I see Murex vanuxemi silvaticus Palmer, on the forum as the only forum mention of Murex in Texas.

Would the Murex above be a drill hole predator, or what others are?

I kinda think having the drill hole in the fossil makes it more interesting, right?

Thanks.

Steve.

[edited to change terminology: from "bore" to "drill".]

Edited August 15, 2011 by steve p.

[Auspex]

I can't help with your questions, other than to agree that boreholes make fossils more interesting, as they are clues to the paleoecology of the site (one of my favorite diversions).

[Terry Dactyll]

Could they of occured many thousands of years after the fossil layer was deposited as some shells actually 'drill' into solid rock to make it their home...These subsequently fill with sediments so the bore holes are not neccesarily for predatory purposes...

[Little_Foot]

The culprit could be the murex, but it could also be any number or moon snails, boring 'worms' (that are actually clams), cone shells, conchs, most anything with a toothed radula...(can we tell I was an obsessive shell collector as a child? Lol!)

I think your best bet would probably be to google 'boring molluscs' or 'boring gastropods' (<- that always makes me laugh!) along with the age and location of the site in question. That will probably give you a better picture of where all the cool bore holes are coming from. Hope that helps, at least a little bit!

[steve p.]

Under the microscope, the bore holes I have observed, appear to be very precisely cut. They also look countersunk and camfered, all characteristics of naticid predation, I believe.

I had done some research on the commonly known gastropod borers:

Moon shells (naticids): they bore but I did not see any reference to them at my digging location.

Rock shells (murex): I found limited reference to them at my digging location.

Cone shells (conus): Conus sauridens are the most common large gastropod for me. I have not seen where these guys make bore holes, though. I thought they speared fish and prey, and often used different poisons etc to immobilize their prey.

I thought there might be an easy answer to this question, as bore holes are so common in bivalves in the Stone City fm.

Here is a series of photos of the most common stuff found at Stone City fm. If anyone recognizes borers among them, please advise. I will google each one myself for clues.

Thanks to all posters.

Steve.

Edited August 9, 2011 by steve p.

[Little_Foot]

You're right on the hunting habits of cone shells, generally when they're hunting they use a harpoon (stored in the radula) that is coated with toxins. However, they can use the radula itself to bore into the shells of other gastropods. I'm assuming it's much less common for cone shells to bore than to harpoon, because from what I'm seeing it's mentioned that they can bore, but predation habit info focuses on harpooning. I am unsure what a bore hole from one would look like.

Buccinidae (true whelks) are also common borers, and they leave very clean circular holes. (Pseudoliva vetusta carinata, first image on your link) Maybe that's your predator?

[NelsonFL]

I found plenty of modern and living Murex shells near Sanibel this last weekend.

[Rodney]

I find this topic to be very interesting, back last year I started collecting fossil bi-valves and what ever I could find from our local river bed which had allmost dried up.

I found several fossil bi valves that have these small holes drilled through the shell, a year later and I now have a collection of these fossilized samples which some are solid rock, some are shell impressions in solid rock.

The area I collected in was from the coastal plains region of southern Ga., I was wondering how can you can determine a date on these bi-valves and gastropods for my area? What I understand a lot of this area was under water 75 million years ago.

Rodney,,

[steve p.]

You're right on the hunting habits of cone shells, generally when they're hunting they use a harpoon (stored in the radula) that is coated with toxins. However, they can use the radula itself to bore into the shells of other gastropods. I'm assuming it's much less common for cone shells to bore than to harpoon, because from what I'm seeing it's mentioned that they can bore, but predation habit info focuses on harpooning. I am unsure what a bore hole from one would look like.

Buccinidae (true whelks) are also common borers, and they leave very clean circular holes. (Pseudoliva vetusta carinata, first image on your link) Maybe that's your predator?

Little foot,

Google has been unproductive in determining which of the linked to gastropods is capable of boring. I google each snail, but google usually returns little, and pretty useless info, for my purpose. (Granted, I may not be able to interpret the search results as I should)

I will just have to assume that one or more of the commonly found snails at this site is responsible for the bore holes.

Thanks to all responders

steve.

[Terry Dactyll]

I have a beautiful ammonite from Lyme Regis that on the back of the slab it is completely drilled out by Piddock's with some shells still inside... The nodule was retrieved from offshore by a diver so basically the Jurassic layer has been the seabed once again and it was colonised by Piddocks... I presume this scenario has been played out many hundreds of times with the fluctuations in the sea level as well as geological forces at work...

PS... there is a small chamfered edge at the entrance to the hole...

Edited August 10, 2011 by Terry Dactyll

[steve p.]

I have a beautiful ammonite from Lyme Regis that on the back of the slab it is completely drilled out by Piddock's with some shells still inside... The nodule was retrieved from offshore by a diver so basically the Jurassic layer has been the seabed once again and it was colonised by Piddocks... I presume this scenario has been played out many hundreds of times with the fluctuations in the sea level as well as geological forces at work...

PS... there is a small chamfered edge at the entrance to the hole...

Very interesting, Terry. Another suspect for my line up.

Thanks.

Steve.

[MikeR]

A beveled bore hole or an inner small hole and an outer larger hole is indicative of Naticid (moon shell) predation. The animal itself burrows the sediment to find other mollusks, envelopes it with its fleshy foot uses a combination of a rsping radula and acids to produce the hole. It can take anywhere from several hours to several days after which the naticid uses its proboscis to eat into the exposed soft organs of its prey.

Reference

Kelley, P.H., Hansen, T.A., Graham, S.E. and Huntoon, A.G., 2001. Temporal patterns in the efficiency of naticid gastropod predators during the Cretaceous and Cenozoic of the United States Coastal Plain; Palaios, v. 166, p. 165-176.

Edited August 11, 2011 by MikeR

[MikeR]

I find this topic to be very interesting, back last year I started collecting fossil bi-valves and what ever I could find from our local river bed which had allmost dried up.

I found several fossil bi valves that have these small holes drilled through the shell, a year later and I now have a collection of these fossilized samples which some are solid rock, some are shell impressions in solid rock.

The area I collected in was from the coastal plains region of southern Ga., I was wondering how can you can determine a date on these bi-valves and gastropods for my area? What I understand a lot of this area was under water 75 million years ago.

Rodney,,

Hi Rodney

I might be able to help you with this. Cenozoic deposits in Georgia run along a belt south of the fall line and are either Eocene or Oligocene. What county were your finds from?

Mike

[jkfoam]

Steve,

In addition to the snail families Muricidae (Genus Murex and Odontopolys at WB) and Naticidae (Genus Polinices, Neverita, and Sinum at WB) the families Buccinidae (Genus Buccitriton at WB) and Turridae (Too many Genera to list at WB) also drill holes in the act of predation. Buccinidae is significant in that B. texanum and B. sagum were quite a population at the WB site, probably rivaling Polinices aratus as the most populus snail there. The Turrids are carnivores but some of the modern Turrids are scavengers and other modern Turrids can be very specific about what they eat restricting themselves to one specific specie of clam, worm, or other critter. Other modern Turrids are not selective so it is hard to tell about paleo Turrids.

Also, the families mentioned above is only a partial list of drilling snails. I wish I was more of a Malacologist so I could contribute more on this interesting subject.

JKFoam

[steve p.]

Steve,

In addition to the snail families Muricidae (Genus Murex and Odontopolys at WB) and Naticidae (Genus Polinices, Neverita, and Sinum at WB) the families Buccinidae (Genus Buccitriton at WB) and Turridae (Too many Genera to list at WB) also drill holes in the act of predation. Buccinidae is significant in that B. texanum and B. sagum were quite a population at the WB site, probably rivaling Polinices aratus as the most populus snail there. The Turrids are carnivores but some of the modern Turrids are scavengers and other modern Turrids can be very specific about what they eat restricting themselves to one specific specie of clam, worm, or other critter. Other modern Turrids are not selective so it is hard to tell about paleo Turrids.

Also, the families mentioned above is only a partial list of drilling snails. I wish I was more of a Malacologist so I could contribute more on this interesting subject.

JKFoam

Jim, you have given me enough info now so I can do some research on my own. I appreciate it. I want to go through the info above and match it against the pdf of common WB gastropods, to help identify the borers in my collection.

I wonder why this list of common fossils omits B. texanum and B. sagum as common as they are?

May I ask how one uses google to determine which gastropods drill? I hate to rely on others if I can learn to search for the info myself.

I certainly have a lot to learn, but its nice to have such a world class site like WB so close.

I recall a trip to the beach, where I was amazed at the number of Whelk shells there. I mean, cubic yards of them, somehow accumulated by the tides. I don't know if they were Lightning or Knobbed whelks. I seem to recall Moon shells also. On my next trip, I think I will take a quick non-scientific survey to see how many clams have bore holes, or appear to be predated by Whelks. Whelks don't bore IIRC, but chip away, or leverage their way in. As big as whelks are, they must massacre their prey. Must be tough to be a clam in Texas.

Do you have any thoughts on the source of damage to the broken gastropods at WB? I am thinking it is a combo of ocean surf/currents/storms and the subsequent forces resulting from burial and diagenesis? Or, what? which accounts for most damage?

This helps me understand the damage I might see on the Bolivar Pen compared to the damage at WB. Just a thought or two will suffice if you have time.

Have a great day.

Steve.

[FossilForKids]

If found on the east coast Ecphora was the first thing that came to my mind. The bore hole is their signature.

FFK

[jkfoam]

I wonder why this list of common fossils omits B. texanum and B. sagum as common as they are?

Steve,

I guess that list is one mans opinion. For me I would never have included Trigonostoma panones juniperum on a list of common fossils from WB.

Also, Whelks comprise a large group of snails that include several Families and some of them are hole drillers.

I think GOOGLE is one of the greatest inventions of all time. You just ask Google a question! For example "What gastropod Families bore holes in their prey". You will get 24,600 hits and in this case the second hit is most appropriate. Try this. ask Google "Do whelks drill holes in their prey". You will get 17,100 hits and the first 3-4 will provide the answer.

As far a broken shells go I think crabs probably do a lot of damage as well as storms ,etc.

JKFoam

[tracer]

i cannot remember how recently it's been mentioned, but at one time hgms had quite a few copies of the emerson book on stone city inverts. not a bad thing to have in the library if one is interested in that formation.

in my opinion, there is no analogy between the condition of the eocene fossils at stone city and the pleistocene/holocene shells at bolivar/high island. the stone city deposition may in large part have been due to storm action, and the shells are original material and quite leached and fragile, so they break if you look at them wrong. they've been subjected to whatever geological stresses have occurred to their environment over many millions of years. the shells at the coast for the most part aren't very leached, and they've mainly just been beaten up from rolling around in the surf.

there are a fair number of lightning whelks at the coast, but they don't represent a majority of the gastropods. shark-eyed moon snails seem to be somewhat seasonal.

[Rodney]

Hi Mike R., I collected the fossils in Colquitt county abt. 14 miles from where I live.

Rodney,,

[steve p.]

i cannot remember how recently it's been mentioned, but at one time hgms had quite a few copies of the emerson book on stone city inverts. not a bad thing to have in the library if one is interested in that formation.

in my opinion, there is no analogy between the condition of the eocene fossils at stone city and the pleistocene/holocene shells at bolivar/high island. the stone city deposition may in large part have been due to storm action, and the shells are original material and quite leached and fragile, so they break if you look at them wrong. they've been subjected to whatever geological stresses have occurred to their environment over many millions of years. the shells at the coast for the most part aren't very leached, and they've mainly just been beaten up from rolling around in the surf.

there are a fair number of lightning whelks at the coast, but they don't represent a majority of the gastropods. shark-eyed moon snails seem to be somewhat seasonal.

Tracer,

I see the book in their library. I will check it out next week.

Of course you are right about few comparisons between recent shells and WB fossils. I just need to do my homework to understand what an extant environment looks like before I go hypothosizing about a fossil one.

Oh, and I have more 1,000,000 year old Bison bones from Bolivar.

Tracer, I appreciate your help as always. Have a good evening. Steve.

[tracer]

seems like i've read that the stone city environment was perhaps on a shelf maybe up to fifty miles offshore. a large amount of what you find at bolivar is actually bay-side stuff from a previous point in time before it was the beach, which everyone should have noticed before they bought property down there. nothing stays the same for long at the coast. or maybe bay-side stuff was just brought over to the gulf side numerous times with retreating storm surges.

but anyway, i'm glad you're studying the faunal assemblages and geoillogicalities. a thirst for knowledge is always more refreshing than a scavenging for marketables.

[MikeR]

Hi Mike R., I collected the fossils in Colquitt county abt. 14 miles from where I live.

Rodney,,

Hi Rodney

Since this is off topic pm me with pics I can be more specific. If the shells are replaced by calcite they are Upper Oligocene Flint River Formation. Molds and casts in massive white limestone would be Upper Eocene Ocala Formation.

Mike

[Pagurus]

Thanks for the interesting topic. The answers are excellent, and I'm looking forward to learning more. I usually have a few living predatory gastropods in my saltwater aquaria, including a moon snail. (Most of the biologists I know around here call it Lunatia heros, but it's also commonly called Polinices heros and it looks like the accepted name is now Euspira h. ). Anyway, I thought it might be interesting to upload a photo of a clam which was eaten by my moon snail, with a hole bored through the shell. You might note that the hole isn't perfectly round. I'm also including a photo of a moon snail shell which was bored by another moon snail. This was found on a beach here in Massachusetts. That hole is rounder. I would say that most of the bored shells I find do have quite round holes, but I do also find them with holes resembling the one from my aquarium. Both holes are about 1/4 inch diameter. I usually keep a few dogwhelks (Nucella lapillus) in the tank as well, and they bore much smaller holes, usually in blue mussels. I'm sorry if this is too far off topic, but I thought it might be interesting.

Mike

[Auspex]

...I'm sorry if this is too far off topic, but I thought it might be interesting.

Mike

Very interesting, and not off topic at all! One of the best tools available to make sense of ichnofossils is comparison to modern examples by known makers.

[steve p.]

Thanks for the interesting topic. The answers are excellent, and I'm looking forward to learning more. I usually have a few living predatory gastropods in my saltwater aquaria, including a moon snail. (Most of the biologists I know around here call it Lunatia heros, but it's also commonly called Polinices heros and it looks like the accepted name is now Euspira h. ). Anyway, I thought it might be interesting to upload a photo of a clam which was eaten by my moon snail, with a hole bored through the shell. You might note that the hole isn't perfectly round. I'm also including a photo of a moon snail shell which was bored by another moon snail. This was found on a beach here in Massachusetts. That hole is rounder. I would say that most of the bored shells I find do have quite round holes, but I do also find them with holes resembling the one from my aquarium. Both holes are about 1/4 inch diameter. I usually keep a few dogwhelks (Nucella lapillus) in the tank as well, and they bore much smaller holes, usually in blue mussels. I'm sorry if this is too far off topic, but I thought it might be interesting.

Mike

Mike,

The bivalve shell you posted looks very worn. I guess I should not be amazed that live shells could get so worn.

Also, the Moon shell you said was drilled by another Moon: Did you see this happen? I ask because I am still unsure how to nail down how the driller was. Primary drillers I know of: Murex and Natacid.

Very nice to see the photos and your comments.

Thanks

Steve