Orca shark interactions

[theropod]

- it is old, and old observations, even scientific, are prone to vague interpretations and exagerations. 50 years ago, scientists seriously considered GWS to be cold man-eaters (Victor Copelson), do we need to rely on this at now ?

That is not an observation, it is a stereotype.

Again, 100 year ago it was generally believed that dinosaurs were slow ectotherms, long since completely revised, but osteological descriptions from this time and before are cited to this day, because people 100-200 years ago where quite capable of describing what they saw, just often lacking what allows us to reach our modern conclusions based on it.

Pseudorca lives in the regions where it is most likely going to find its adequate preys items since the habitat is determined too by the feeding habits. The great white is a coastel predator because its preys are coastal.

So by your logic tiger>>polar bear, since the latter doesn't coexist with elephants?

Because a pod of FKW certainly appears more theatening than seagulls. It doesn't change that FKW had no intention to kill the sperm whales, that's no effective predation. I think that flesh grazing has been suggested for GWS too on adults humpbacks.

I wouldn't be surprised by this, but if you want to make it an argument, could you post where you found this "suggested"?

And who sais the FKWs had no intention of killing?

There's a misunderstanding here. I don't say that the orca cannot kill bigger game than GWS, of course it can in absolute termes given its much larger size. I ask evidences that it can kill individually larger prey items proportionnally to its size than GWS, if this ever happens as the orca is pack hunter and that even a smaller-sized minke whale is usually dispatched by the entire pod.

Then you shouldn't use this as a basis for attacking my credibility.

To be fair, I'm surprised that you take this account like if it was written in the stone and that you so fastly make a day "O. orca can kill much larger preys than GWS individually".

It might be worth going back a few pages and reading what my statement was.

The examples you cite involve terrestrial much smaller predators than both orca and GWS. I have the sheer impress, and that needs to be investigated, that the bigger is the predator, the less big are its preys items compared to it, individually. I just don't know any case where a lone orca attacked and killed a prey twice its size.

We had a lenghty discussion where you claimed the exact opposite, that the bigger the predator, the bigger its prey items have to be in relation. You even posted a study supporting this, but it was only dealing with teleosts if I remember correctly.
I don't know any account where a great white shark killed a prey item twice its size, even though, if it is capable of that individually, we are more likely to also observe it.

And what's so important about being warm-blooded?

[stomatopod]

Oct 6, 2014 22:13:23 GMT 5 theropod said:

That’s only maximum size, average size doesn’t seem too different given that male FKWs mature at 500cm. And what they lack in maximum size they can arguably make up for with the help of the pod.
Also it’s not sure whether the giant Cuban shark was actually weighed or whether the weight was just an estimate (link→).

You claimed that GWS were about the same size as FKW, which they are not. The largest female FKW was about the same size as the average GWS(whose statistics might be flawed, there are very few adults in most analyses, which is, accounting for the latest research, due to what almost was a relic population, expanding after exploitation).
And then, of I remember it properly, there is another 3.1 ton specimen.
And I do not know what the purpose of bringing up pod size is, as the point is purely upon size.

Oct 6, 2014 22:13:23 GMT 5 theropod said:

Its true that Great white sharks would be expected to prey on proportionately larger prey than mammal eating orcas, but it doesn’t seem to be the case, the biggest that has been recorded is approximately the shark’s own size. As I noted, that’s a bit strange. EDIT: Perhaps that’s due to the still-underrated factor of ramming as a means of killing in odontocetes, Ford et al. (2005) report "repeated ramming" to be a common method of dispatching minke whales, but not biting.

The argument was about what prey a single specimen can take.
If you only take somewhat verifiable accounts, the maximum size of the prey is about the same. I do not hold anecdotal evidence in high regard. Its even worse than circumstantial evidence.
I have not even seen an account of Orcas taking even a minke whale on their own.

Oct 6, 2014 22:13:23 GMT 5 theropod said:

The shark in the account (Pyle et al. 1999) was estimated at 3-4m (thus probably already transitioned to a mammalivorous diet, if that’s what you are getting at), and was killed by a small, if adult, female Orca (estimates 4.7-5.3m long, typical adult size is 7m). Theres no reason to believe trophic interactions between more typical or large-sized orcas and great whites would be different.

Well if it was 4 meters in lenght, them yes it was most likely transitioned. But not at 3 or 3.5 meters. Have you seen the footage? I think 4 meters is highly unlikely for that shark. If you compare it to the Orca it is pretty much dwarfed. Given that the fish rating species of Orcinus only reach around 7 meters a length of 5 meters is not really small for a female. Mammal eaters usually do not even regard fish as food.
The usual trophic interaction between fish eaters and GWS is mutual avoidance, as the footage off Tasmania shows.
I am still looking for the link on old CF with the account of the GWS killing the subadult Orca. Then its N=2 vs. N=1 respectively.

Oct 6, 2014 22:13:23 GMT 5 theropod said:

And just like other marine apex predators, they appear to mostly feed on comparatively small prey, that is pinnipeds in adults and fish in young sharks. Tricas & Mccosker (1984) compiled data on the diet of 33 great whites, and fish was the most common prey item, followed by pinnipeds. In the 9 sharks from California analyzed in the study, the stomach contents consisted entirely of fish. Its the young sharks that mostly prey on fish, while adults mostly take seals. But attacks on juvenile mysticetes (Three cases→) and beaked whales (one successful here→, involving a juvenile cuvier’s whale) are still a rare ocurrence for any white shark, especially compared to the huge amount of data on their diets.

If you consider that amount of data huge...
So, we have 2 studies geographically limited.
The first describes predation on a species that nearly hit the fan, no wonder that there are no more incidences.
I already know the second source, and there is circumstantial evidence of more attacks on beaked whales.
A tip: maybe also look for accounts of predation on other species, like Southern Right Whales. I know there are.

Oct 6, 2014 22:13:23 GMT 5 theropod said:

Flesh-grazing can be parasitism, but seagulls don’t force sperm whales to form a marguerite formation, do they? Some forms of flesh-grazing are more akin to predation, namely those involving a full-on attack. Doing that on sperm whales is quite indicative of macropredatory habits, after all even orcas only rarely attack them.

Well maybe look at what the gull do to whales off South America. The whales are not pleased by the gulls behaviour and have a higher rate of juvenile mortalty.
And yes, flesh grazing is facultative parasitism.
I would never claim for my cetopsids have macropredatory habits.

[theropod]

You claimed that GWS were about the same size as FKW, which they are not.

From what I read a 5m great white is a fairly large specimen. Casey & Pratt (1985, first paper here→) report females of 5.18 and 5.62m as the next largest reliable atlantic great whites after the Cuban shark. That’s not very recent, but you get the picture.
Both are well within the size range of Pseudorca crassidens (weight estimates of 1.3 and 1.7t based on the mean of various regression equations). So for now we have no evidence that any but the largest great whites outsize it by any significant amount. At first I was lured into believing that too, but it requires proper evidence.
Of the 137 sharks that they personally examined, the biggest was 4.97m long.

The largest female FKW was about the same size as the average GWS

Do you have evidence for that?

And I do not know what the purpose of bringing up pod size is, as the point is purely upon size.

Its the impact on ecology. False killer whales may not reach sizes as large as the largest great whites, or at least none have been reported so far. But they can take the same prey.

The argument was about what prey a single specimen can take.

So?

If you only take somewhat verifiable accounts, the maximum size of the prey is about the same. I do not hold anecdotal evidence in high regard. Its even worse than circumstantial evidence.

Circumstantial evidence is a great thing. Of course you have to be able to determine the most likely conclusion from is, otherwise its worthless. And it has to itself rely on proper data, otherwise its also anecdotal evidence.

How exactly are observations of behaviour verifyable? Can you go there and see them happen yourself?

Well if it was 4 meters in lenght, them yes it was most likely transitioned. But not at 3 or 3.5 meters. Have you seen the footage?

Tricas, T. C.; McCosker, J. E.: Predatory Behaviour of the White Shark
(Carcharodon carcharias) with notes on its biology. Proceedings of the
California Academy of Sciences, Vol. 43 (1984); 14; pp.221-234:
"At about 3 m TL, the teeth broaden at the base and take on the diagnostic triangular serrated form. Unlike the long narrow teeth, this shape is well-suited for gouging and cutting pieces from prey too large to swallow whole."

What footage?

Given that the fish rating species of Orcinus only reach around 7 meters a length of 5 meters is not really small for a female. Mammal eaters usually do not even regard fish as food.

The orcas in questions were probably transients, because the same two individuals probably were the ones that consumed a california sea lion before one of them killed the shark.

Fish is a fishy taxon, perhaps killer whale segregate more based on size than based on artificial groupings of animals not at all closely related?

The usual trophic interaction between fish eaters and GWS is mutual avoidance, as the footage off Tasmania shows.

What footage?

If you consider that amount of data huge...

That amount of data was just the part dealing with records of sizeable cetacean prey. Obviously it’s not huge, because this kind of prey is uncommon in sharks. There can be no doubt that the predatory habits of Great white sharks are very well studied. It continues to receive a huge amount of attention in that regard.
On the other hand, most people probably don’t even know what a false killer whale is, let alone what it feeds on, and it is commonly noted to be poorly studied.

I already know the second source, and there is circumstantial evidence of more attacks on beaked whales.

Maybe you would like to post it?
Didn’t you argue that this wasn’t relevant, being basically just evidence of flesh-grazing?

[creature386]

Oct 7, 2014 20:16:38 GMT 5 theropod said:

The largest female FKW was about the same size as the average GWS

Do you have evidence for that?

I just google scholared a bit:

The maximum recorded length in males is 610cm (Leatherwood and Reeves, 1983) and in females 506 cm (Perrin and Reilly, 1984).[…]Scheffer and Slipp (1948) report a 523-cm-long animal of 902 kg.

www.aquaticmammalsjournal.org/share/AquaticMammalsIssueArchives/2000/AquaticMammals_26-01/26-01_Kastelein.pdf
Using the square-cube law, you get a maximum weight of roughly 800 kg for female FKW's.

[Grey]

That is not an observation, it is a stereotype.

Again, 100 year ago it was generally believed that dinosaurs were slow ectotherms, long since completely revised, but osteological descriptions from this time and before are cited to this day, because people 100-200 years ago where quite capable of describing what they saw, just often lacking what allows us to reach our modern conclusions based on it.

That wasn't a stereotype back then, obsolete studies (the "rogue shark") determined the GWS as a dangerous man-eater.

I just question the reliabiity of such an observation (a sole orca attacking and killing an adult humpback) since it has not been seen and documented since.

So by your logic tiger>>polar bear, since the latter doesn't coexist with elephants?

That's irrelevant, polar bears and tigers are separated by huge environmental and geographical barreers, FKW and GWS aren't. One lives in areas where its main preys, squids and fishes, are present, the other lives in coastal areas where its main preys, marine mammals, are present.

If FKW absolutely wants to be in the same trophic position than GWS, they just have to change their main diet and moves in pinnipeds inhabited regions.

I wouldn't be surprised by this, but if you want to make it an argument, could you post where you found this "suggested"?

That was in one tv doc where adults humpbacks weared clear distinctive bite marks that matched those of GWS. I think I have seen this in one document but I cannout found the source again.

And who sais the FKWs had no intention of killing?

Who says the seagulls have no intentions of killing ?

Deliberate attack like O. orca practices on baleen and sperm whales and flesh grazing is quite distinctive.
I don't think O. orca has been spotted flesh grazing mysticete or sperm whales.

It might be worth going back a few pages and reading what my statement was.

Fair enough, you just stated that O. orca kills by its own larger preys than C. carcharias, given its much larger size, right ?

We had a lenghty discussion where you claimed the exact opposite, that the bigger the predator, the bigger its prey items have to be in relation. You even posted a study supporting this, but it was only dealing with teleosts if I remember correctly.
I don't know any account where a great white shark killed a prey item twice its size, even though, if it is capable of that individually, we are more likely to also observe it.

And what's so important about being warm-blooded?

Are you sure it was me ? Because it's been a while I think about that : it's more rare to see giants predators killing by their own larger preys than smaller ones in a wolerine-like fashion. I don't remember that study, I doubt it was me.

I don't refer that GWS can kill preys twice its size, I don't think this has been strictly reported, but it can sometimes engage and kill preys items as larger or larger than itself. I doubt that any GWS would engage a prey twice its size, unless the prey is severely wounded.

As I said, I think that individually, the predatory power of GWS and transients orcas at similar size is...somewhat similar. But I ask for any account where an orca has killed by its own a prey larger than itself. Given their natural social habits, that seems difficult.

Of course it's facultative, but warm-blooded preys are quite active and reactive to sharks attacks. There's a difference for a GWS between attacking a sea turtle and a sea lion of same size. No please, I don't want another discussion about the flawed superiority of warm-blooded over cold-blooded, I know how complex the question is and that's not the point.

[theropod]

That wasn't a stereotype back then, obsolete studies (the "rogue shark") determined the GWS as a dangerous man-eater.

Hence a generalized opinion about the animal that has since then been revised, right?

If FKW absolutely wants to be in the same trophic position than GWS, they just have to change their main diet and moves in pinnipeds inhabited regions.

These regions are already the feeding grounds of another large predator.
Predators don’t have to hunt the same prey, they can specialize on different types.

That was in one tv doc where adults humpbacks weared clear distinctive bite marks that matched those of GWS. I think I have seen this in one document but I cannout found the source again.

From when they were young perhaps? Or, of course, flesh grazing?

Who says the seagulls have no intentions of killing ?

Their beaks do.

Deliberate attack like O. orca practices on baleen and sperm whales and flesh grazing is quite distinctive.

By what means was that not a deliberate attack?

Fair enough, you just stated that O. orca kills by its own larger preys than C. carcharias, given its much larger size, right ?

Exactly.

Are you sure it was me ?

Yes.

Because it's been a while I think about that : it's more rare to see giants predators killing by their own larger preys than smaller ones in a wolerine-like fashion.

That is certainly the case. But we don’t know whether it is because they are less capable of it, because larger predators are generally rare, because they are marine and thus more rarely observed and/or because a giant predator will more rarely encounter prey larger than itself, and has a greater selection of smaller, easier prey at its disposal. So we can not attribute that to a general inability of large marine predators to bring down prey larger than themselves.

I don't remember that study, I doubt it was me.

My bad on who posted that study. We had that debate, but it was creature was the one who found the paper. You clearly agreed with it though (while you will actually see me arguing that giant predators are/were not particularly specialized for giant prey–which does not mean they can not take it on occasion).
Here’s the study: people.uncw.edu/scharff/publications/MEPS%202000.pdf
Here’s where we discussed it: theworldofanimals.proboards.com/thread/54?page=16

I don't refer that GWS can kill preys twice its size, I don't think this has been strictly reported, but it can sometimes engage and kill preys items as larger or larger than itself. I doubt that any GWS would engage a prey twice its size, unless the prey is severely wounded.

Then why do you expect me to bring more solid accounts of orcas doing it?

But I ask for any account where an orca has killed by its own a prey larger than itself. Given their natural social habits, that seems difficult.

Here you have the answer to why this is so rarely observed.

Of course it's facultative, but warm-blooded preys are quite active and reactive to sharks attacks. There's a difference for a GWS between attacking a sea turtle and a sea lion of same size. No please, I don't want another discussion about the flawed superiority of warm-blooded over cold-blooded, I know how complex the question is and that's not the point.

It seems to be, otherwise you wouldn’t be using it as an argument.
Sea turtles aren’t mammaly, but not really any more "cold-blooded" than great whites either, at least not all of them: www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0013925
And neither are they easy prey for sharks: www.youtube.com/watch?feature=player_detailpage&v=foBxvwOnEB0
A sea turtle is different from a pinniped not primarily because of its metabolism, but because of its morphology. That being said, I think a turtle would be a more challenging prey for a shark than a seal of the same weight.

Could you elaborate on how exactly being "cold-blooded" makes the prey of false killer whales inferior to that of Great whites? Do swordfish or tuna for example become easier to catch than sea lions because they are not mammals? Even if that was the case, the only thing it would imply would be about catching, not killing.

[Grey]

Hence a generalized opinion about the animal that has since then been revised, right?

Obsolete studies. That's not the only example.

These regions are already the feeding grounds of another large predator.
Predators don’t have to hunt the same prey, they can specialize on different types.

And the FKW is primarily a predator of small-sized fishes and squids.

From when they were young perhaps? Or, of course, flesh grazing?

No, not when they were young because the scars enlarge with age. I've referred earlier to an adult grey whale with a massive healed bite mark on the caudal peduncle. Unless one believes it's from a living megalodon-like shark, that was made by a GWS when the whale was very young. So more likely flesh-grazing.

Their beaks do.

I don't see the relevance here, with their beaks seagulls are dangerous for the calves, but there's no intent to kill.

By what means was that not a deliberate attack?

No intent to kill, the FKW were only withdrawing morcels of flesh from the whales bodies. There's a difference with actual predation with hunting tactics.

Exactly

.

Well fair enough.

That is certainly the case. But we don’t know whether it is because they are less capable of it, because larger predators are generally rare, because they are marine and thus more rarely observed and/or because a giant predator will more rarely encounter prey larger than itself, and has a greater selection of smaller, easier prey at its disposal. So we can not attribute that to a general inability of large marine predators to bring down prey larger than themselves.

Well, despite their great size, orcas and GWS can easily encounter much larger preys items than they. Orcas is more difficult since they're social and usually do the job with others pod members, but to my knowledge GWS are not known to have attacked twice heavier preys animals. Surely, the selection and easier access to smaller preys-items might explain this, but I don't think that any giant predator (>several tonnes) have the skills of some felines or wolverines at taking down much larger preys on an usual basis.

My bad on who posted that study. We had that debate, but it was creature was the one who found the paper. You clearly agreed with it though (while you will actually see me arguing that giant predators are/were not particularly specialized for giant prey–which does not mean they can not take it on occasion).
Here’s the study: people.uncw.edu/scharff/publications/MEPS%202000.pdf
Here’s where we discussed it: theworldofanimals.proboards.com/thread/54?page=16

You're misunderstanding, I supported "the larger the predator, the larger the prey", like you said for the orcas preys items compared to the smaller white shark. But here I talk about larger preys items comparatively to the size of the predator. Maybe it's me who confused this back then.

Then why do you expect me to bring more solid accounts of orcas doing it?

I'm asking you a solid documented account of an orca individual attacking and killing a Megaptera-sized prey item.

Well, i highly doubt that, because transient orcas are way larger than great white sharks.

I wrote at similar size.

Here you have the answer to why this is so rarely observed.

That does not explain only one alleged occurence in 140 years, orcas are largely studied and observed since decades, individuals have been known and observed attacking and killing individually preys items (smaller sharks, seals...) many times, so I'm still asking for an account where an orca by its own kills an adult humpback. I don't think an orca can kill individually a 30 tons prey item.

It seems to be, otherwise you wouldn’t be using it as an argument.
Sea turtles aren’t mammaly, but not really any more "cold-blooded" than great whites either, at least not all of them: www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0013925
And neither are they easy prey for sharks: www.youtube.com/watch?feature=player_detailpage&v=foBxvwOnEB0
A sea turtle is different from a pinniped not primarily because of its metabolism, but because of its morphology. That being said, I think a turtle would be a more challenging prey for a shark than a seal of the same weight.

Could you elaborate on how exactly being "cold-blooded" makes the prey of false killer whales inferior to that of Great whites? Do swordfish or tuna for example become easier to catch than sea lions because they are not mammals? Even if that was the case, the only thing it would imply would be about catching, not killing.

I told you I don't want to discuss the cold-blooded/warm-blooded subject.

I think a seal is much more difficult to catch for a shark than a turtle of the same weight.

[theropod]

Oct 9, 2014 8:22:21 GMT 5 Grey said:

Hence a generalized opinion about the animal that has since then been revised, right?

Obsolete studies. That's not the only example.

And a specific observation of behaviour can not be obsolete, at worst anecdotal. So your examples are irrelevant.

And the FKW is primarily a predator of small-sized fishes and squids.

Small-sized? Not necessarily.

No, not when they were young because the scars enlarge with age. I've referred earlier to an adult grey whale with a massive healed bite mark on the caudal peduncle. Unless one believes it's from a living megalodon-like shark, that was made by a GWS when the whale was very young. So more likely flesh-grazing.

More likely flesh-grazing it is. Or it was attempted, but unsuccessful predation (an explanation that works with all bitemarks on living animals actually).

I don't see the relevance here, with their beaks seagulls are dangerous for the calves, but there's no intent to kill.

Seagulls are dangerous for calves that are, according to your own statements, easily the size of an adult great white shark?

No intent to kill, the FKW were only withdrawing morcels of flesh from the whales bodies. There's a difference with actual predation with hunting tactics.

You don't know the intentions of the false killer whales, do you?
And that has nothing to do with it being a deliberate attack, it obviously was. What attacks in the animal kingdom are not deliberate? Maybe those by sharks on humans, because they mistake them for different prey, but apart from such cases I can't think of much.
Do you think the fkws mistook the sperm whales that they engaged in an open, aggressive confrontation for "small fish and squid"?

That is certainly the case. But we don’t know whether it is because they are less capable of it, because larger predators are generally rare, because they are marine and thus more rarely observed and/or because a giant predator will more rarely encounter prey larger than itself, and has a greater selection of smaller, easier prey at its disposal. So we can not attribute that to a general inability of large marine predators to bring down prey larger than themselves.

Well, despite their great size, orcas and GWS can easily encounter much larger preys items than they.

There are proportionately fewer animals in its ecosystem that are bigger than an orca than there are animals bigger than a lion for example, so by inference it is less likely to encounter prey larger than itself. In part because an orca is in a different size class, in part ebcause giant whales are rare.

Orcas is more difficult since they're social and usually do the job with others pod members, but to my knowledge GWS are not known to have attacked twice heavier preys animals.

Not to my knowledge either, but only a fraction of predatory interactions in the sea actually gets recorded, even in animals as relatively well-studied as orcas and great whites.

Surely, the selection and easier access to smaller preys-items might explain this, but I don't think that any giant predator (>several tonnes) have the skills of some felines or wolverines at taking down much larger preys on an usual basis.

That may rather be linked to aquatic habits than to being a giant predator, given that it is the case. The capabilities of predators also depend on their habitat, for example no terrestrial predator in their size range takes prey as large as some eagles, and crocodiles in turn take proportionately smaller prey than terrestrial predators of similar size (but to what extent that is the result of their functional anatomy and to what extent of their habitat, and to what extent they depend on each other is of critical importance).

You're misunderstanding, I supported "the larger the predator, the larger the prey", like you said for the orcas preys items compared to the smaller white shark. But here I talk about larger preys items comparatively to the size of the predator. Maybe it's me who confused this back then.

Yes, larger predators tend to take larger prey, but as we just discussed giant predators can subsist on prey items smaller than themselves toothat was my point back then. Whether or not larger predators have more difficulty in taking larger prey items, or merely more difficulty finding them and/or better abilities to support themselves with smaller prey--that we can't tell.

Then why do you expect me to bring more solid accounts of orcas doing it?

I'm asking you a solid documented account of an orca individual attacking and killing a Megaptera-sized prey item.

I'm afraid that doesn't answer the question.

That does not explain only one alleged occurence in 140 years, orcas are largely studied and observed since decades, individuals have been known and observed attacking and killing individually preys items (smaller sharks, seals...) many times

It does in my opinion.
Of the small fraction of predatory interactions between orcas and other prey that are observed, the vast majority concerns groups of them. Now imagine how unlikely, it is to witness one actually killing something that large, when large whales themselves are rare and orcas, like other giant predators, mostly target prey smaller than themselves!

so I'm still asking for an account where an orca by its own kills an adult humpback.

I gave you one, that wasn't enough for you. There are other references listed in the first quote I gave, the paper is freely accessible. I suggest you help track them down if you aren't satisfied with the currently posted evidence.

I don't think an orca can kill individually a 30 tons prey item.

I see no reason for it not to, I also think the great white shark could have the capability of bringing down prey of similar size in relation to its body. I just think its exceedingly rare, and thus never witnessed.

I told you I don't want to discuss the cold-blooded/warm-blooded subject.

Then don't use it as an argument, if you do, you should be prepared to discuss it. You cannot give an argument and refuse to support it, that's like making a claim and refusing to support it.

I think a seal is much more difficult to catch for a shark than a turtle of the same weight.

To catch or to kill? A turtle seems more difficult to prey on, despite being slower. And it isn't slower because it isn't a mammal, it is slower because it has a carapace and different locomotory system, which in turn make it more difficult to actually kill once you catch it. But that's irrelevant, because tuna or salmon certainly aren't slower than pinnipeds.

[creature386]

Oct 9, 2014 16:19:19 GMT 5 theropod said:

I don't think an orca can kill individually a 30 tons prey item.

I see no reason for it not to, I also think the great white shark could have the capability of bringing down prey of similar size in relation to its body. I just think its exceedingly rare, and thus never witnessed.

Well, Grey's frequently used example involved a blue whale that was 18 m long and thus probably weighed between 30 and 40 t. That being said, maybe three adult killer whales could kill such a whale (theoretically), but looking at how much they struggled, I have some doubts about the capacity of a single individual to do so.

[theropod]

I think their struggle was due to the whale’s sustained speed rather than their inability to kill it. They also have a considerable rate of failure with minke whales, and there can hardly be any doubt that a group of orcas could easily kill one (and they do actually, unless the minke whale can outdistance them), after all they don”t even fight back when cornered.

Btw could someone repost the source? I thought I had downloaded it, but it seems I haven’t.

[creature386]

Here you go:

Approximately 30 killer whales assaulted an 18.2 m (60 ft.) blue whale. Two killer whales stayed ahead and two lagged behind while others surrounded the blue whale from the sides and underneath in an apparent effort to prevent escape. Some even leaped onto the back of the blue whale in what is believed to be an attempt to drown it.

The SeaWorld vessel watched as the group took turns biting flesh and blubber from their prey. After five hours, the herd broke off their attack. Perhaps the killer whales were resting or they may have had their fill, but the final fate of the severely injured blue whale was not known.


www.seaworld.org/infobooks/killerwhale/dietkw.html

[stomatopod]

Oct 7, 2014 20:16:38 GMT 5 theropod said:

From what I read a 5m great white is a fairly large specimen. Casey & Pratt (1985, first paper here→) report females of 5.18 and 5.62m as the next largest reliable atlantic great whites after the Cuban shark. That’s not very recent, but you get the picture.
Both are well within the size range of Pseudorca crassidens (weight estimates of 1.3 and 1.7t based on the mean of various regression equations). So for now we have no evidence that any but the largest great whites outsize it by any significant amount. At first I was lured into believing that too, but it requires proper evidence.
Of the 137 sharks that they personally examined, the biggest was 4.97m long.

As we know, at 4.5 meters female GWS only start to mature. I still hold the theory that GWS population is currently shifted towards smaller sizes due to human impact.
GWS petty much are K-strategists and the small amount of adults is best explained with the depletion of the stock. The few last centuries and especially the 20th were not that rosy for this species.
I also think that your source is somewhat outdated(and local), you may take a look at the work of Henry Mollet especially take a look at the reevaluation of the Kanga and Malta specimens.

Oct 7, 2014 20:16:38 GMT 5 theropod said:

Do you have evidence for that?

Well, Jingfengopteryx already should have given you an idea. Another problem is that we do not have that many data on the average size of FKW.
But I think that given the fact that the largest GWS is about 50% larger than the largest "theoretical" FKW should give us some hints.

Its the impact on ecology. False killer whales may not reach sizes as large as the largest great whites, or at least none have been reported so far. But they can take the same prey.

Yes, but we were speaking about sizes, not ecology, which we discussed separately. Also, the latter is speculative.

So?

I think you were not adressing my argument, but I guess that was unintentional.

Circumstantial evidence is a great thing. Of course you have to be able to determine the most likely conclusion from is, otherwise its worthless. And it has to itself rely on proper data, otherwise its also anecdotal evidence.

Yes, but the attack on the Humpback is pretty much anecdotal. Some local Greenlanders tell stories that get down in the record. The largest known prey for a single Orca I can come up with are Elephant Seals.
Maybe they take minke whales on their own but I have not found a good record on that.

How exactly are observations of behaviour verifyable? Can you go there and see them happen yourself?

Hmm, the amount and style of documentation should suffice. Video footage is even better but no neccesary.
I also find these kind of questions kinda irritating.

Tricas, T. C.; McCosker, J. E.: Predatory Behaviour of the White Shark
(Carcharodon carcharias) with notes on its biology. Proceedings of the
California Academy of Sciences, Vol. 43 (1984); 14; pp.221-234:
"At about 3 m TL, the teeth broaden at the base and take on the diagnostic triangular serrated form. Unlike the long narrow teeth, this shape is well-suited for gouging and cutting pieces from prey too large to swallow whole."

Read what Estrada et al. and Kim et al. have to say on this. The isotopic data is kinda clear.
Of course the teeth start broadening before the shift, just as lots of other species even get teeth before even using them.

What footage?

Willy eating Bruce, aka the incident from the paper. It´s all over Youtube.

The orcas in questions were probably transients, because the same two individuals probably were the ones that consumed a california sea lion before one of them killed the shark.

They were from the LA pod which are not transients, but maybe another Ecotype(To which hypothetical species they belong is another question) from more southern waters.
They are even smaller than residents, around the ize of offshores. They only smaller type is type D.

Fish is a fishy taxon, perhaps killer whale segregate more based on size than based on artificial groupings of animals not at all closely related?

This is petty much contrary to what we know about the different ecotypes. And you apply phylogeny were you should apply Biochemistry and Ecology.
There are people that have problems with seafood but not with any tetrapods. Diet is not restricted by phylogeny but by other causes.
And I am pretty sure that all know populations of Transients, Type A and II Orcas most commonly do not eat fish. May it be due to preferences or nutritional reasons.

What footage?

Both Orcas and GWS eating during a large congregation of biomass. I think it was one of the first threads of this Forum.

That amount of data was just the part dealing with records of sizeable cetacean prey. Obviously it’s not huge, because this kind of prey is uncommon in sharks. There can be no doubt that the predatory habits of Great white sharks are very well studied. It continues to receive a huge amount of attention in that regard.
On the other hand, most people probably don’t even know what a false killer whale is, let alone what it feeds on, and it is commonly noted to be poorly studied.

Huh? the diet has been extensively studied? Really? the best studies are based on Isotopic evidence.
And of course the incidents of GWS eating northern right whale calves cannot be that huge, the latter has a population of what?

Maybe you would like to post it?
Didn’t you argue that this wasn’t relevant, being basically just evidence of flesh-grazing?

Its alredy in the source, but that might have been scavenging. Its still better than an anecdote, but you are right, it is not of great value.


I want to add that predation on mysticetes is mostly limited by them escaping before incapacitating them.

[theropod]

creature386: Thanks! I should have just had the sense to look at the appendices in the paper we already discussed earlier though.

Oct 9, 2014 22:57:26 GMT 5 stomatopod said:

As we know, at 4.5 meters female GWS only start to mature.

Based on what source? There’s no consensus on that.

I still hold the theory that GWS population is currently shifted towards smaller sizes due to human impact.

I wouldn’t say that necessarily shifts the population, it just makes it more rare generally, and if it does, why shouldn’t it do the same with other animals?

GWS petty much are K-strategists and the small amount of adults is best explained with the depletion of the stock. The few last centuries and especially the 20th were not that rosy for this species.

There are very few species for which they were rosy.
That they are K-strategists actually implies that their size distribution is not so skewed towards juveniles, so this doesn’t explain the small amount of adults in any other context but the generally small number of great whites. But the sample of False Killer whales is probably not any better, it’s pretty much the number of stranded individuals.

I also think that your source is somewhat outdated(and local), you may take a look at the work of Henry Mollet especially take a look at the reevaluation of the Kanga and Malta specimens.

That has nothing to do with it, these specimens are exadraordinarily large either way.
But you were talking about the largest reported weight only, which is for the Cuba specimen (which is claimed to be far heavier than predicted for its lenght). In fact, it”s almost the weight that would be predicted for a 7m individual.

Well, Jingfengopteryx already should have given you an idea. Another problem is that we do not have that many data on the average size of FKW.

No, we don’t. But according to the source I posted earlier, when discussing the alledged case of the 3.8m fkw with shark bite marks, males mature at 500cm. This is likely an average figure, so if it means osteological maturity it is the average adult size, and if it is social or sexual maturity it is less. Hence my conclusion that a 3.8m specimen is small, even by female standards.
Hence the lower bound for the average size is about 5m for males and 4.2m for females.

But I think that given the fact that the largest GWS is about 50% larger than the largest "theoretical" FKW should give us some hints.

what do you mean by "theorethical" FKW?

Yes, but we were speaking about sizes, not ecology, which we discussed separately. Also, the latter is speculative.

It is?

Well, yes, the largest great whites do seem to get bigger than FKWs. I’m not convinced that this is the case with typical sizes, much less typical sizes of the whole population (which is important for their trophic status).

I think you were not adressing my argument, but I guess that was unintentional.

I didn’t adress it because I didn’t see the argument in "The argument was about what prey a single specimen can take.". What relation was it supposed to have to my post?

Circumstantial evidence is a great thing. Of course you have to be able to determine the most likely conclusion from is, otherwise its worthless. And it has to itself rely on proper data, otherwise its also anecdotal evidence.

Yes, but the attack on the Humpback is pretty much anecdotal.

Anecdotal evidence can be perfectly adequate for establishing that something has ocurred. And nobody is claiming it to not be extraordinary. I was not discussing statistical probabilities of this ocurring (as I wrote in my response to Grey, I think they are very small), I was discussing the largest prey these animals can take–if we trust this account, that’s the maximum confirmed size in the case of orcas, and I think that makes it perfectly legit to say orcas can individually take larger prey than great whites, in accordance with their body size.
I even acknowledged that comparable feats in proportion to their body size may be just as possible for great whites.

Some local Greenlanders tell stories that get down in the record.

I don’t want to discuss what stories some local Greenlanders might or might not tell. The account I posted was that of a danish Zoologist and naval officer.

The largest known prey for a single Orca I can come up with are Elephant Seals.

Southern elephant seal bulls that is.

Maybe they take minke whales on their own but I have not found a good record on that.

Neither have I. It appears Minke whales are already difficult to catch for a pod of orcas. But a single killer whale could certainly kill a member of a slower species (e.g. a humpback or right whale) this size, for example a subadult individual.

Read what Estrada et al. and Kim et al. have to say on this. The isotopic data is kinda clear.

Full citations?

Of course the teeth start broadening before the shift, just as lots of other species even get teeth before even using them.

Sharks are not among those species, why shouldn’t they transition at the same time as their tooth shape changes, or even, why shouldn’t their tooth shape change in response to increased predation on mammals?

Willy eating Bruce, aka the incident from the paper.

How cute!
You mean this→

The shark doesn’t look like it couldn’t be 4m, and of course a 4.7-5.3m Killer Whale dwarfs such a shark, it’s conservatively 33-133% more massive. Anyway, you can discern far too little from the footage to use it as evidence for their sizes, you can’t even see their entire bodies.
But that’s still a small orca, just like it is a small shark. A large orca would dwarf a large shark just in the same way or even more, ergo I don’t see why an 8m orca shouldn’t be able to do that with a 6m shark.

They were from the LA pod which are not transients, but maybe another Ecotype(To which hypothetical species they belong is another question) from more southern waters.
They are even smaller than residents, around the ize of offshores. They only smaller type is type D.

Where do you take your data from?

Anyway, what does it change? Does it make large transient orcas any smaller? And if those orcas ate a sea lion before one killed the shark, why wouldn’t a large transient orca kill and eat a shark?

Fish is a fishy taxon, perhaps killer whale segregate more based on size than based on artificial groupings of animals not at all closely related?

This is petty much contrary to what we know about the different ecotypes. And you apply phylogeny were you should apply Biochemistry and Ecology.

And you think a great white shark is the same as a salmon in terms of biochemistry and ecology?

There are people that have problems with seafood but not with any tetrapods.

And I trust they tried going on a cetacean and pinniped diet? And certainly also chondrichthyans?
Your argument would actually support the importance of phylogeny.

Diet is not restricted by phylogeny but by other causes.

You just used a phylogenetic category though.

And I am pretty sure that all know populations of Transients, Type A and II Orcas most commonly do not eat fish. May it be due to preferences or nutritional reasons.

I haven’t claimed that wasn’t the case. That wasn’t my point.
My point was that an orca preying on mammals wouldn’t preclude it from taking a shark. "Fish-eaters" means "teleost eaters", I don’t think sharks are actually important for that categorisation, they are not a common enough prey.

What footage?

Both Orcas and GWS eating during a large congregation of biomass. I think it was one of the first threads of this Forum.

I’m not sure. I definitely don’t distinctly recall having seen that.

That amount of data was just the part dealing with records of sizeable cetacean prey. Obviously it’s not huge, because this kind of prey is uncommon in sharks. There can be no doubt that the predatory habits of Great white sharks are very well studied. It continues to receive a huge amount of attention in that regard.
On the other hand, most people probably don’t even know what a false killer whale is, let alone what it feeds on, and it is commonly noted to be poorly studied.

Huh? the diet has been extensively studied? Really? the best studies are based on Isotopic evidence.

If it wasn’t better studied than in False Killer whales, you probably wouldn’t consider the account of predation on a humpback whale any more anecdotal than white shark predation on right whales or beaked whales, because it would have received its own paper like the accounts in white sharks.

And of course the incidents of GWS eating northern right whale calves cannot be that huge, the latter has a population of what?

Humpback whales aren’t exactly common either.
If this being rare was just a matter of the whale’s population, why aren’t there attacks on calves of other whales that are less rare?

Its alredy in the source, but that might have been scavenging. Its still better than an anecdote, but you are right, it is not of great value.

Better for what? Not better evidence of predation by your definition. There is also circumstantial evidence for False Killer Whale attacks on adult humpbacks and sperm whales, that doesn’t mean they prey on them.

[theropod]

A selection from Appendix I in Jefferson et al. 1991:

Date	Location	Description	Cooperation?	Kill?	Source
Pre-1886	Tigalda Island, AKm U.S.S	2 KWs attack a large Fin Whale	Y	?	Turner (1886)
6 July 1908	Sukkertoppen, W. Greenland	Whaler record of 2 KWs killing a Fin Whale	?	Y	Reeves & Mitchell (1988)
1983-87	Greenland	8 observations of chases or attacks involving 4-5, 8-10, 2,2,2,2,2-4 KWs)	?	?	Heide-Jorgensen (1988)
7 July 1984	Faroe Islands	2 KWs attack a Fin Whale (report from fishermen)	?	?	Bloch & Lockyer (1988)
1800s	Sea of Okhotsk	3 KWs attack and mortally-wound a large Bowhead	Y	Y	Bullen (1898)
11 September 1984	Baffin Island, eastern Canada	2 KWs presumably attack single Bowhead, while 12 other Bowheads socialize nearby	?	?	Finley (1990)
November 1961	Southern CA, U.S.A.	Second-hand report of single KW attacking and Killing single Grey [whale]	N	Y	W.F. Samaras and S. Leatherwood (unpubl.)
February 1966	Southern CA, U.S.S.	Second-hand report of 2-3 KWs attacking 3 Greys, killing 1	?	Y	W.F. Samaras (in litt.)

I think that should lend a little more credibility to the account I already posted. It’s rare on the whole, but there is still a fairly good record of small groups or single Killer Whales killing large baleen whales, sometimes attacking groups of them.

---

Reference:
Jefferson, T. A.; Stacey, P. J.; Baird, R. W.: A review of Killer Whale interactions with other marine mammals: predation to co-existence. Mammal Review, Vol. 21 (1991); 4; pp. 151-180

[Grey]

And a specific observation of behaviour can not be obsolete, at worst anecdotal. So your examples are irrelevant.

As long as there's no modern reliably documented cases, my examples are reliable. But the further data you've brought could revise this a bit.

But I don't rely too much on very old observations not widely reported and supported since.

Small-sized? Not necessarily.

Mainly smaller-sized than adults GWS preys items. The abstract I've posted about the stomach contends of a sample of FKW does not show large-sized preys items. The squids species found in great number in them are small-sized.

We have hints about their food preferences from
looking at stomach contents collected from strandings and have found that their diet consists predominantly of squid and fish. Like orca, they are known
to take dolphins and have also been observed
attacking humpback and sperm whales. The Pseudorca, rather than attempting to kill these larger
whales, may be intending only to remove mouthfuls
or intimidate their larger cousins. Another theory
has it that the Pseudorca are harassing these bigger
species to the point of vomiting, then feeding on
the regurgitations.
However co-operation may be the driving force
behind their frequent associations with other species of dolphins, in particular bottlenose dolphins.


www.orcaresearch.org/wp-content/uploads/2011/08/Visser-2010-familiar-imposter-Pseudorca.pdf

More likely flesh-grazing it is. Or it was attempted, but unsuccessful predation (an explanation that works with all bitemarks on living animals actually).

I think it's pretty easy to distinct deliberate attempts to kill and flesh-grazing and I don't see why you insist in that case of FKW when flesh-grazing on large whales bodies is reported from others species. If you want to demonstrate that these FKW were actually trying to kill one of the whales, then bring some evidence.

Seagulls are dangerous for calves that are, according to your own statements, easily the size of an adult great white shark?

Yes and so ?

You don't know the intentions of the false killer whales, do you?

And you say that I'm the one personnally attaking you here ? My adequate response here : "because perhaps you do, genius ?".

And that has nothing to do with it being a deliberate attack, it obviously was. What attacks in the animal kingdom are not deliberate? Maybe those by sharks on humans, because they mistake them for different prey, but apart from such cases I can't think of much.
Do you think the fkws mistook the sperm whales that they engaged in an open, aggressive confrontation for "small fish and squid"?

As long it is stated to be flesh-grazing and no deliberate attempt to kill that's fine to me.

There are proportionately fewer animals in its ecosystem that are bigger than an orca than there are animals bigger than a lion for example, so by inference it is less likely to encounter prey larger than itself. In part because an orca is in a different size class, in part ebcause giant whales are rare.

And if FKW were mainly made to kill big games they would move in waters where big games preys live. But they actually live in the waters where their main preys items consisting of fishes and squids actually live.

Not to my knowledge either, but only a fraction of predatory interactions in the sea actually gets recorded, even in animals as relatively well-studied as orcas and great whites.

Absolutely, that's why we rely on what is documented, studied and reliably supported, not on over-speculations.

It does in my opinion.

No it doesn't. But the others cases you've reported are more interesting.

To catch or to kill? A turtle seems more difficult to prey on, despite being slower. And it isn't slower because it isn't a mammal, it is slower because it has a carapace and different locomotory system, which in turn make it more difficult to actually kill once you catch it. But that's irrelevant, because tuna or salmon certainly aren't slower than pinnipeds.

So you're suggesting that beside sea turtles, modern aquatic and marine reptiles are just as fast, active, reactive and agil than seals ?

Tunas and salmons are exceptionnal cases among fishes.

I claim that a GWS has less problem to catch and kill a 50 kg turtle than a 50 kg seal.

I claim that a large GWS is individually a more formidable predator than a FKW.