stomatopod
Junior Member
Gluttonous Auchenipterid
Posts: 182
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Post by stomatopod on Oct 5, 2014 1:43:14 GMT 5
Then what constitutes a killer whale?
There are most likely at least 4 species, and the smaller ones certainly overlap with the GWS in their feeding habits.
Only Transients (and Variants), Antarctic Type-A and their North Atlantic sister clade regulary prey on large Cetaceans.
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Post by theropod on Oct 5, 2014 1:46:33 GMT 5
In the wider sense, killer whale refers to 3 genera…
Several populations preying on large cetaceans regularly already constitutes something not known for Great White Sharks or False Killer Whales.
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Post by theropod on Oct 5, 2014 2:31:30 GMT 5
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Post by Grey on Oct 5, 2014 2:36:19 GMT 5
What source sais that they are targeted more rarely? And many of the fish prey false killer whales take (Yellowfin tuna, wahoo, swordfish…) is easily comparable in size to harbour seals or sea lions. The quote from Compagno I've posted. Makos sharks target too on swordfish, tunas... that does not means the mako overlaps the great white trophic systems. More generally speaking, GWS is a bigger game hunter than FKW and there is very slight, but still extant, hints that it might on occasion prey on FKW, whereas the other situation is completely unevidenced. And on a physical viewpoint, I doubt the largest FKW are comparable to the largest females GWS, in girth and predatory power. |
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Post by theropod on Oct 5, 2014 2:48:51 GMT 5
The quote does not say so.
Also if I ask for evidence for something also claimed in a quote, wouldn’t it rather pointless to argue that quote to be evidence?
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Post by Grey on Oct 5, 2014 2:50:51 GMT 5
The quote says mostly on fishes and squids. That specifies how the FKW is not all that comparable to adults GWS in trophic systems.
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Post by Grey on Oct 5, 2014 2:54:07 GMT 5
The quote does not say so. Also if I ask for evidence for something also claimed in a quote, wouldn’t it rather pointless to argue that quote to be evidence? The quote itself is filled with references when he stipulates that GWS operate at higher trophic systems than the FKW. |
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Post by theropod on Oct 5, 2014 3:18:56 GMT 5
References that cannot be verified are not references–I for my part couldn’t find the first one, and I might have found the second but it’s inaccessible. Where is the rest of that paper?
As I already pointed out, of course FKWs prey most commonly on fish and squid, those preys are simply more commonly available in its habitat than pinnipeds. That does not automatically imply being lower in the trophic system as you claim, unless you want to imply false killer whales are lower in the trophic system than cookiecutter sharks.
I already wrote, the fish prey of false killer whales broadly overlaps the mammalian prey of adult great white sharks in terms of size, and they prey on dolphins too, just like great whites.
And no, that quote does not say the large prey in question is targeted more rarely by false killer whales than by great white sharks. Neither does it claim it, nor does it give evidence for it. You claimed it.
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Post by Grey on Oct 5, 2014 3:26:38 GMT 5
References that cannot be verified are not references–I for my part couldn’t find the first one, and I might have found the second but it’s inaccessible. Where is the rest of that paper? As I already pointed out, of course FKWs prey most commonly on fish and squid, those preys are simply more commonly available in its habitat than pinnipeds. That does not automatically imply being lower in the trophic system as you claim, unless you want to imply false killer whales are lower in the trophic system than cookiecutter sharks. I already wrote, the fish prey of false killer whales broadly overlaps the mammalian prey of adult great white sharks in terms of size, and they prey on dolphins too, just like great whites. And no, that quote does not say the large prey in question is targeted more rarely by false killer whales than by great white sharks. Neither does it claim it, nor does it give evidence for it. You claimed it. Yes, FKW are lower in trophic systems than GWS since they target mostly fairly smaller preys. The cookiecutter is a parasite even targetring adult baleen whales, not comparable at all. I already wrote too that Mako sharks (and Longimanus) also target on these fast big fishes and on dolphins. C. leucas and G. cuvier too target dolphins. Does that means these sharks are at the same trophic systems than C. carcharias ? I guess not. I've presented a reference from Compagno quite specific, I'd ask to presen another reference which explains clearly the contrary of what is claimed here. |
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stomatopod
Junior Member
Gluttonous Auchenipterid
Posts: 182
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Post by stomatopod on Oct 5, 2014 4:02:54 GMT 5
In the wider sense, killer whale refers to 3 genera… Several populations preying on large cetaceans regularly already constitutes something not known for Great White Sharks or False Killer Whales. Of course I mean THE killer whale, genus Orcinus. And those several populations most likely constitute a different species. They are genetically, phisically and ecologically different and do not interbred with other varieties. Most scientist seem to agree that there are multiple species of killer whales(And we certainly would have 2 more valid species described by now if we knew what O. glacialis and nanus would correspond to.) 3/4 do not feed on large cetaceans. D. orca as described by Linnaeus most likely corresponds to one of those, of is a amalgam of multiple varieties. We can fairly say that there is a large overlap in dietary preferences. |
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Post by Grey on Oct 5, 2014 4:21:25 GMT 5
Will there be a study which will finally clarify this and distinct the various orcas Types at the end ?
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Post by elosha11 on Oct 5, 2014 11:02:49 GMT 5
Creature, Compagno obviously refers to the pinnipeds habits shared by KW and GWS. And KW dont hunt large whales on a daily basis either. What I said was simply that it is hard to imagine that the gap in prey size between a KW and a GWS is smaller than in FKW vs GWS. They may not hunt really large whales commonly, but they attack relatively large whales a lot more common than great whites so. Accounts of killer whales preying on false killer whales are a lot better documented than predation on false killer whales by great white sharks. Yes but also keep in mind for purposes of this thread, that we should be comparing the morphological features of an individual orca to an individual great white. An individual orca would almost certainly never take on an adult sizeable humpback or sperm whale; orca pods take on such prey. So even though individual orcas are certainly on the whole larger and more powerful than the great white, there isn't really all that much difference in the size of the prey each can individually take down. Both a solitary orca and a great white can individually prey on adult elephant seals for instance. This is a prey item that an individual false killer whale would almost certainly never attack. I think, that at least in part that's what Compagno references. A great white is both designed and inclined to take larger prey items - on the whole - than a solitary FKW would be. |
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Post by elosha11 on Oct 5, 2014 11:11:58 GMT 5
They feed on bony fish and squid because pinnipeds are restricted to coastal waters while false killer whales are generally pelagic. But their larger prey items (dolphins, tuna, whale calves) are comparable. Yes but again, you are talking about large prey items FKW normally take in a group attack, not as individual predators. Again, since this thread is primarily concerned with comparing orcas and pseudo orcas' individual predatory capabilities, we should not penalize the solitary great white by comparing their prey selection to the large prey FKW normally take in a group attack. And still, it bears noting that FKW's, even in pods, are documented to feed primarily on medium size fish like mahi mahi. Their attacks on large mammal prey such as dolphins is documented as a very occasional feeding, whereas great whites in many parts of the world target comparatively large pinnipeds, tuna and cetacean prey on a regular basis. Great whites in Guadalupe, the Farallones, the Mediterranean, and off Australia all frequently take such large prey items. |
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Post by elosha11 on Oct 5, 2014 11:38:14 GMT 5
Yes orcas are far larger generally than predatory sharks, but even here this evidence of orca predation on macro-predatory sharks must be taken with a healthy grain of salt. In almost all of these occasions posted, the shark was simultaneously attacked by multiple orcas, and the shark itself was a very small specimen. (Not counting Greenland/pacific shark encounters because although they can be large, they are sluggish and have small teeth and probably pose little challenge for orcas. Similarly threshers are small toothed/small prey hunters and could not really pose much threat) For instance, in the mako shark account you've posted, the shark was 1.2 to 1.5 meters long! That's a tiny baby mako, and really not impressive prey for an orca pod. Likewise, the tiger shark killed recently was only seven feet long, a young subadult. The great white killed in 1997 was a juvenile of about 10 feet long, and the orca in question was about 15 to 16 feet long, and known as an adult of one of the smaller orca resident subspecies. These animals were a bit closer in size, but it was still a huge mismatch both in size and predatory experience. These accounts - by themselves - don't really prove anything, other than that a much larger animal will prevail over a much smaller animal, and the conflict is made even more one sided when a group of much larger animals attacks a smaller solitary one. Just in the last few days a video surfaced of a much larger great white attacking a smaller great white when both were attempting to feed on some researcher's bait. Guess which animal dominated (and apparently may have wounded/killed the other)? The larger shark of course. That holds about as much evidentiary value to me as the orca preying on the great white. If a solitary 16 foot great white came across a solitary 10 foot orca, the great white would kill it if it was so inclined. Doesn't mean anything other than one much larger predator will dominate another smaller predator. Does this mean that I think a great white is a equal one on one fighter/predator to an orca? Absolutely not, because even at maximum sizes, the orca will be significantly larger and almost always surrounded by pod mates. But is a large great white, or even a very large tiger or mako shark a very dangerous prey item for a single or even multiple orcas? Yes because even attacking as a group, a large shark could do some serious damage to an orca. So while I find these videos of orcas killing sharks impressive and clear evidence of their status as apex predator, I have no problem believing that a large solitary orca and a large great white would each keep a respectful distance from the other - for obvious reasons. |
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Post by elosha11 on Oct 5, 2014 12:09:20 GMT 5
These encounters are so uncommon because these two have different habitats and are both very high in their respective trophic systems (only Orcinus is higher and has been recorded to prey on both on occasion), which means they will generally avoid each other. elosha11: As I already wrote, based on the paper I posted 3.8m would actually be below the size at maturity, unless the female maximum size diverges more strongly from the size at maturity than that of the male, for which I see no reason. Or do you have any data on their average size suggesting otherwise? Btw the link you posted states the following about their size: Female size slightly above 5m, male size slightly below 6m. This→ is consistent with that, but rounded. 5m is ~83% of 6m, and ~83% of 5m is ~4.2m. 3.8m is just about ~91% (calculated with the exact values) of adult size. That doesn’t mean it wasn’t adult, but if it’s below the typical size they mature at it’s small for an adult. I’m not sure what type of maturity that figure corresponds to, if it is osteological maturity that value is actually interchangeable with average adult size, if it is sexual maturity it is less. So based on currently available data, the specimen was below average. Probably the same anecdote we have, since that seems to be the only one there is. But still it comes without real support (as already detailed), which is probably why it is expressed so tentatively. Also, note how there’s no indication of the state of maturity or size. Who sais a false killer whale couldn’t take a sub-average or immature great white shark? Some type of combative/predatory interaction apparently takes place on very rare occasions, but that is no evidence for the shark being more formidable at the same size, unless there is evidence for the shark coming out on top in such a scenario, which there can not be without at least examining both the combatants, or, better still, actually witnessing the interaction. Or perhaps it doesn’t seperate them at all, just detail it was the superficial shark bites that were responsible. See the problem with that account? It provides no proper documentation of the shark’s role in that Pseudorca’s demise except that it bore superficial bite wounds, and no information on the nature of their interaction was available in the first place. Should that really be the sole piece of evidence to make people believe sharks beat killer whales at parity, and the sole piece of evidence to make them claim great whites are more dominant predators than FKWs? Look we may just have to agree to disagree here. The evidence and other support I have to suggest, (notice I didn't say prove, nor have I ever said prove) that great whites or other large sharks occasionally prey on FKW is (1) a 3.8 meter female bitten by a large shark likely contributing to its stranding (2) an adult FKW with recently healed large shark bite around its middle (often an attack point) likely bitten by great white or tiger (2) a respected research paper re FKW's suggesting large sharks occasionally feed on FKW's (4) a second FKW research source again stating large sharks likely prey on FKW on occasion (found yesterday, will try to find again and post), (5) research from Compagno indicating that great whites tackle larger prey more frequently than FKW) and (6) quite likely evidence of great white predation on pilot whales, a dolphin that may even be larger than the FKW, but not as formidable. (Still not entirely a bad proxy). You say this evidence and opinions hold little value. I disagree, I think as a whole it suggest what I and the FKW researchers agree upon: That large sharks, (most likely large great whites and/or large tigers), will on occasion attack and probably on occasion kill a FKW. This doesn't mean that I think a false killer whale would have no chance against a comparably size great white. I think it's quite possible that FKW have sometimes prevailed in such encounters, either individually or as a pod. But on balance, the evidence suggest that more likely than not it is the shark that is usually the aggressor in one on one predatory encounters. And yes such interaction are probably very rare for many reasons, not the least of which the animals are somewhat evenly matched and dangerous to each other. In fact, FKW may even displace large sharks on occasion since they operate in large pods. Lastly, I want to make clear that I am not using this contest between great whites and FKW as a proxy to prove a great white would overcome a similar sized orca. Your last paragraph in the above post seemed to imply that. I don't mix and match conflicts. I have no idea who would win between a 5000 pound orca and a 5000 pound shark. Each would have advantages, but the contest would also give an artificially unfair advantage to the shark because it would represent a very large and very experienced shark against a presumably small orca subspecies or a subadult/small adult from one of the larger subspecies. So it's pretty much impossible to "fairly" measure this contest, the animals are simply in two different size strata. I really do enjoy these types of discussions; great insights from everyone all around.  |
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