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Post by theropod on Oct 3, 2014 21:55:23 GMT 5
Of course Pilot whales have more formidable jaws than bottlenose dolphins, they are 6 times the size. I was discussing size parity, and for their size pilot whales, just like Bottlenose dolphins etc. are not taking large prey, ergo their predatory apparatus isn’t built for this either. Compare the skull of a pilot whale ( here→) to that of a false killer whale ( here→), and you’ll see what I mean. Obviously the general consensus here seems to be that great white sharks are larger than false killer whales, so if that’s true I can see even less relevance in the single account of a small individual succumbing after sustaining bite injuries under mysterious circumstances (probably also heavily connected to the stranding, as the article claims the injuries to be superficial). But what’s relevant about them is that they, unlike the other taxa you list and more like Orcinus, are apex predators with weaponery clearly suited for attacking large animals. This is probably related to predation, but it could have been a failed predatory attempt on the whale’s part as well as on the shark’s. And nobody knows what the corresponding shark looked like afterwards. False killer whales tend to beach quite frequently, and shark bite marks are also quite frequent but not necessarily a serious thread. Sperm whales also have scratches inflicted on them by quid claws, but that doesn’t mean any squid would be a serious thread to the whale. My point is that there is just no ground for anyone to claim to know what would happen in an interaction between a similar-sized false killer whale and great white shark, unless we get real accounts that actually clearly show a shark killing a false killer whale, or vice versa. |
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Post by Grey on Oct 3, 2014 22:06:30 GMT 5
I'd add that even if a bite was actually made when the cetacean was young and smaller-sized, that doesn't change the relative size of the shark which attacked it since healed wounds grow up with the whale with age.
An evidence of this is the observation of an adult grey whale which had an ENORMOUS circular bite mark on the caudal peduncle, which could correspond to a megalodon-sized predator. Obviously, it was made by a great white when it was a calf...
Plus, the fact the cetacean wears a healed bite mark doesn't mean primarily it killed its agressor but that it simply succeeds to escape it. Or that a conspecific of the cetacean came to help against the predator.
Like most predators, sharks normally dont engage animals too much dangerous, so I dont think that all these healed bite marks are indicative at all the victim killed the agressor, simply that it escaped it thanks to its athletic skills.
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Post by elosha11 on Oct 3, 2014 22:14:18 GMT 5
For easy reference here's the picture of the FKW with a shark bite in 2010, with the researcher's comments below. It's pretty clear it's recently healed injury on an adult they've been keeping track of for 10 years. It's interesting that the researcher's also characterize it as a shark attack.  False killer whale with recent shark bite wound and a long-term injury to the dorsal fin, August 5, 2010. Photo by Dan McSweeney. This individual is HIPc127 in our catalog, first documented off Maui in March 2000 (with the bent dorsal fin), and seen several times since both off Maui and the island of Hawai‘i. The shark bite wound behind the dorsal fin is the first time we've documented evidence of an attack by a large shark on a false killer whale in Hawai‘i. |
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Post by theropod on Oct 3, 2014 22:18:56 GMT 5
Of course, that just makes it more likely for the shark to be larger than the whale (because the whale was smaller). Nobody ever seems to care about measuring those bite wounds unfortunately, but in most cases it must be pointless anyway.
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Post by elosha11 on Oct 3, 2014 22:28:13 GMT 5
Of course Pilot whales have more formidable jaws than bottlenose dolphins, they are 6 times the size. I was discussing size parity, and for their size pilot whales, just like Bottlenose dolphins etc. are not taking large prey, ergo their predatory apparatus isn’t built for this either. Compare the skull of a pilot whale ( here→) to that of a false killer whale ( here→), and you’ll see what I mean. Obviously the general consensus here seems to be that great white sharks are larger than false killer whales, so if that’s true I can see even less relevance in the single account of a small individual succumbing after sustaining bite injuries under mysterious circumstances (probably also heavily connected to the stranding, as the article claims the injuries to be superficial). But what’s relevant about them is that they, unlike the other taxa you list and more like Orcinus, are apex predators with weaponery clearly suited for attacking large animals. This is probably related to predation, but it could have been a failed predatory attempt on the whale’s part as well as on the shark’s. And nobody knows what the corresponding shark looked like afterwards. False killer whales tend to beach quite frequently, and shark bite marks are also quite frequent but not necessarily a serious thread. Sperm whales also have scratches inflicted on them by quid claws, but that doesn’t mean any squid would be a serious thread to the whale. My point is that there is just no ground for anyone to claim to know what would happen in an interaction between a similar-sized false killer whale and great white shark, unless we get real accounts that actually clearly show a shark killing a false killer whale, or vice versa. Theropod, I don't think we're really all that far apart here. I would never say that this evidence means for sure that a 18 foot great white would definitely be able to prey on an 18 foot false killer whale. All I am suggesting is that the evidence does to me indicate more likely than not, that great whites sometimes view false killer whales as a potential prey. Of course, I have no idea how large or small the sharks were in these particular encounters, but I wouldn't exactly characterize a 3.8 meter FKW as small, more like an average sized female. That's close to 4 meters, which is a probably a fairly average sized great white, at least by median size. I'm guessing that it is similar for an average sized female FKW. As to the stranding element, sure it's possible FKW could have already been stranded and the shark took opportunistic bites. But it wasn't just superficial bites, as you claim, the FKW's dorsal fin was heavily damaged by a shark bite. It would be pretty risky for a shark to follow a stranded FKW to shore just to take a bite, so I think it's a bit more likely that the shark and FKW interacted in some way, the FKW got bit and wounded, and the wounds and/or the stress of the encounter caused it to strand. Either scenario is of course possible, but I think the latter is more plausible. |
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Post by theropod on Oct 3, 2014 23:09:30 GMT 5
That wasn’t what I meant, but that the stranding was eventually just as responsible for the whale’s death as the shark’s bites were. Yes, it does seem the encounter would have been responsible for the stranding, but that doesn’t even have to mean the shark would have been able to kill it–whales in perfectly healthy condition also strand. I don’t know the average size of female Pseudorca, but according to Baird et al. (1989) male Pseudorca mature at about 500cm in TL. Assuming similar ratio between maximum size and size at maturity in both sexes, this 3.8m Pseudorca was well below the typical size at maturity even for females. This is just a rough calculation of course, but I feel quite justified in saying it was a small individual. However this does make me think about whether we can really say Pseudorca crassidens as a taxon is smaller in size than C. carcharias. Some hard data would be needed on that matter. Also my point is not whether or not great white sharks sometimes view false killer whales as prey (but the current state of the evidence is not really indicative of that imo), I was discussing the notion of sharks being more formidable than delphinids of equal size (again a notion not backed up by actual accounts of a shark getting the better off a macropredaceous dolphin at equal sizes, or the reverse). But that this matter is so difficult to actually find evidence for is also an indication that they don’t prey on each other. What’s your source for the dorsal fin being "heavily damaged"? The only mention of this case that I’m aware of only gives this one sentence about the injuries: www.fearbeneath.com/2009/12/shark-snacks-on-false-killer-whale/A damaged dorsal fin is not necessarily a heavily damaged dorsal fin, just like a cookiecutter shark”s bite isn’t a great white’s bite.
Baird et al. 1989: whitelab.biology.dal.ca/rwb/1stRec.pdf |
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Post by elosha11 on Oct 4, 2014 0:23:07 GMT 5
The maximum size female FKW I've seen listed is either slightly above or slightly below 5 meters and the maximum size for male is slightly over 6 meters. Based on that, I think 3.8 meters would fall in the average spectrum for a female. I definitely agree that neither the great white nor the FKW are frequent targets for the other. They prefer easier to hunt prey, and I'm sure great whites don't want to mess with a pod of FKW's. However, the evidence we do have suggests some type of combative/predatory interaction does take place. By the way, we're not the first to suggest that large sharks may prey on false killer whales. The Society of Marine Mammology states on its page for false killer that "False killer whales are probably occasionally killed by large sharks, and there is one documented attack by killer whales on false killer whales in New Zealand." www.marinemammalscience.org/index.php?option=com_content&view=article&id=463&Itemid=299My guess is that they don't make this statement without any support; they've probably seen evidence or anecdotes that suggest that sharks may occasionally prey on false killer whales. Lastly, the reason I stated the dorsal fin was "heavily" damaged was that it described the other shark wounds as superficial so I was contrasting the injury to the dorsal fin to the other less serious injureis. But you are correct, the actual wording just stated the dorsal fin was just "damaged," although it certainly implies it was the more serious of the injuries. |
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Post by creature386 on Oct 4, 2014 0:24:43 GMT 5
However this does make me think about whether we can really say Pseudorca crassidens as a taxon is smaller in size than C. carcharias. Some hard data would be needed on that matter. Given that 4.5 seems to be a rather generous minimum size for an adult great white female, I am pretty sure we can't. But that this matter is so difficult to actually find evidence for is also an indication that they don’t prey on each other. It could also simply indicate that such cases are not as easy to document as the seal attacks in shallow water. Generally, I have the impression that few interactions of great white sharks with something else than seals is really well studied. But I of course don't deny that such events are extremely uncommon. |
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Post by theropod on Oct 4, 2014 1:08:16 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? |
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Post by Grey on Oct 4, 2014 7:56:03 GMT 5
C. carcharias is higher in tophic systems than P. crassidens.  Their maximum size is close, but in absolute terms, females GWS appear a bit larger and bulkier than the largest males FKW which are rather elongated creatures. |
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Post by theropod on Oct 4, 2014 13:54:24 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.
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Post by creature386 on Oct 4, 2014 14:12:56 GMT 5
Broadly overlapping with the killer whale? I hope this is very rough because the killer whale has a food source (larger whales) that is completely inaccessible to the great white shark. I don't think we can say that the great white is above the false killer whale, but not below the killer whale.
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Post by Grey on Oct 4, 2014 23:16:00 GMT 5
The larger preys items of FKW are comparable but they are targeted more rarely. FKW is primarily a predator of fishes and squids.
Creature, Compagno obviously refers to the pinnipeds habits shared by KW and GWS. And KW dont hunt large whales on a daily basis either.
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Post by theropod on Oct 4, 2014 23:29:32 GMT 5
What source sais that they are targeted more rarely?
And many of the fish false killer whales take (Yellowfin tuna, wahoo, swordfish…) are easily comparable in size to harbour seals or sea lions.
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Post by creature386 on Oct 5, 2014 0:33:17 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. |
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