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Post by elosha11 on Sept 30, 2014 23:19:06 GMT 5
www.dailymail.co.uk/sciencetech/article-2770645/WATCH-Brutal-moment-gang-killer-whales-paralyse-tiger-shark-ripping-pieces-toy-carcass.html#ixzz3ET9Z95T8The pics and video in this link provide probably the best documented predation of orcas on shark thus far captured. Once again we see the orca's intelligence, teamwork, and learned behavior in inducing tonic mobility. And I am struck by the enormous size disparity between the tiger shark and the orcas. Granted the tiger shark is a subadult at only 7 feet long, but the orcas make it look like a minnow. Orcas are truly the dominant apex predator in the ocean today. I would love to be seen how orca pods would interact with giant megatoothed/other prehistoric sharks, mosasaurs and pliosaurs. As of now, they just don't have any predatory rival that can come close to exceeding their size, much less their teamwork.
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Post by elosha11 on Sept 30, 2014 23:30:29 GMT 5
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Post by elosha11 on Oct 2, 2014 22:48:26 GMT 5
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Post by elosha11 on Oct 2, 2014 23:11:44 GMT 5
It should be noted that in all of the documented orca predations on great whites, tiger sharks, and mako sharks, the orca(s) in question was far larger than the shark, and the shark itself was a juvenile or a subadult at best. Now even the largest of those sharks will be significantly smaller than a large orca, but it remains to be seen how a single orca would interact with a 15-20 foot great white, a 14-16 foot tiger shark, or a 12-14 foot mako. My guess is that the largest and most dangerous sharks would be avoided as too great a risk of injury or only attacked in a pod.
It is also noteworthy that whenever sharks and dolphins are equivalent in size, such as bottlenose, spinner dolphins, or false killer whales, the evidence suggests the shark more often than not has the predatory advantage. But the orca's massive size puts it in a category all its own.
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Post by elosha11 on Oct 2, 2014 23:25:19 GMT 5
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Post by creature386 on Oct 2, 2014 23:35:03 GMT 5
I adapted the title to these posts. I hope you have no problem with this elosha.
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Post by elosha11 on Oct 2, 2014 23:40:17 GMT 5
Sure, that's fine.
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Post by theropod on Oct 3, 2014 2:00:44 GMT 5
It should be noted that in all of the documented orca predations on great whites, tiger sharks, and mako sharks, the orca(s) in question was far larger than the shark, and the shark itself was a juvenile or a subadult at best. Now even the largest of those sharks will be significantly smaller than a large orca, but it remains to be seen how a single orca would interact with a 15-20 foot great white, a 14-16 foot tiger shark, or a 12-14 foot mako. My guess is that the largest and most dangerous sharks would be avoided as too great a risk of injury or only attacked in a pod. It is also noteworthy that whenever sharks and dolphins are equivalent in size, such as bottlenose, spinner dolphins, or false killer whales, the evidence suggests the shark more often than not has the predatory advantage. But the orca's massive size puts it in a category all its own. There is no recorded direct interaction between a false killer whale and a shark of the same size. Of course compared to bottlenose or spinner dolphins sharks have the upper hand–these dolphins specialize in small fish and squid, while the sharks you are referring to are built to hunt far larger prey. |
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Post by Grey on Oct 3, 2014 8:05:08 GMT 5
I personnally favor a large white shark over a large false killer whale but I don't think they ever interact because of the risk of severe injuries for both and that the FKW are mostly social, so immune to any GWS anyway.
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Post by theropod on Oct 3, 2014 17:50:16 GMT 5
These aren’t the same size, a Great White Shark reaches larger sizes than a False Killer whale.
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Post by creature386 on Oct 3, 2014 18:22:56 GMT 5
The explanation why they don't interact still works when you replace the white shark with an equally sized shark.
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Post by theropod on Oct 3, 2014 19:01:35 GMT 5
Sure, that’s absolutely valid.
I wasn’t referring to that, but to the claim of sharks being superior to dolphins at aqual sizes.
That only seems to hold true if you segregate to use sharks specialized in killing larger prey. Of course these sharks are more formidable combatants than dolphins that specialize in small fish and squid, but I’m sure the reverse is true as well (for example a false killer whale and a megamouth shark of equal size, or an orca and a basking shark…).
Interactions between similar sized macrophagous dolphins and sharks have simply not been recorded. Because white sharks, orcas and false killer shales have overlapping size ranges but are still rarely the same size. And considering a great white shark more formidable doesn”t have a thing to do with it if you do so because it’s bigger.
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Post by elosha11 on Oct 3, 2014 19:45:42 GMT 5
I'll admit the evidence of shark and FKW interaction is quite sparse, but that which does exists seems to indicate sharks (likely great whites) will occasionally attack a FKW. I posted evidence of a sizeable shark bite on an adult FKW in Hawaii in the dolphin shark interaction thread, and there's also the fearbeneath website, which indicates a shark biting a false killer whale. www.fearbeneath.com/2009/12/shark-snacks-on-false-killer-whale/. It was a 3.8 meter female, so certainly not the largest FKW, but it was an average sized adult. I also posted a video in the shark/dolphin thread which strongly suggested great whites can hunt pilot whales, another formidable cetacean with similar size and predatory capabilities of the FKW. And I posted video of makos killing sizeable dolphins. I completely agree though that bottlenose, spinner and other small mouthed dolphins are not nearly as formidable as an orca or a FKW, although they are still powerful and agile animals that could potentially be dangerous to sharks. Is this evidence conclusive that great whites will usually prey on FKW's? Absolutely not. But it's what we have to work with. I have not yet seen or heard of FKW preying on sharks of any kind, much less a great white. I'm sure great whites and FKW's have had their share of conflicts over the millions of years of their co-existence, I simply think the shark would be a bit more likely to be in the predatory mode in a one on one situation. As to size, great whites are probably a bit bigger on the maximum scale than a FKW, but they really are comparable. |
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Post by theropod on Oct 3, 2014 20:35:52 GMT 5
Pilot whales have similar predatory capabilities to false killer whales? That would be entirely new to me. Pseudorca has been reported to prey large prey like tuna and dolphins, and occasionally humpback whale calves, as well as attacking and flesh-grazing sperm whales–I’d say its relative prey size isn’t dissimilar from the great white shark’s. I know no such behaviour in pilot whales which are said to prey on small fish and squid. I don’t think healed bite wounds help your case; they show that the delphinid got away even after being bitten, and we don’t know at what stage of its life it received them. Even the only documented case where a false killer whale was actually killed by a shark doesn’t tell us what became of the shark (it could have died too in that confrontation, after all the whale escaped), or how large it was, as the actual confrontation wasn’t witnessed. That Pseudorca is so poorly studied in the wild has implications for what we can say about its ecology. Of course it’s a pelagic species, so either way I wouldn’t expect a bulk of evidence for interactions with coastal sharks to turn up, but we’d probably have more if there was more material.
www.cascadiaresearch.org/robin/pseudorcaemm2008.pdfwww.researchgate.net/publication/230250139_ATTACK_BY_FALSE_KILLER_WHALES_%28PSEUDORCA_CRASSIDENS%29_ON_SPERM_WHALES_%28PHYSETER_MACROCEPHALUS%29_IN_THE_GALPAGOS_ISLANDS |
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Post by elosha11 on Oct 3, 2014 21:30:53 GMT 5
You are correct as to pilot whales' predatory capabilities. I thought I had read that they could also take larger prey, but I apparently was remembering accounts of false killer whales. Still, they are comparable in size to FKW and great whites, and certainly have larger/more formidable jaws/teeth than bottlenose, harbor, spinner dolphins. As to the shark bites on FKW, I agree with you it's not conclusive evidence and could support any number of scenarios, but it does lead to one irrefutable fact, that on at least two occasions a large shark bit and wounded a FKW. Also, on the one picture I posted in the other thread, I believe the wounds were relatively freshly healed, which would indicate the bite was made on an adult and certainly the bites on the stranded FKW were made while it was an adult. The article indicated a damaged dorsal fin and other superficial bites, which may have led to its stranding. So what we have is limited evidence that FKW's are bitten by sharks, which I think you would agree is usually (not always) indicative of a predatory attempt. To the whale's credit it successfully evaded the shark, but then again so do pinnipeds on occasion, up to the size of elephant seals. Also, look at the location of the bites, right in the middle of FKW's bodies on both occasions, near the vital organs. That's a common body area for great whites to attack when preying on dolphins. I agree that you can't draw definitive conclusions, but I think it's not an unreasonable inference that these incidents may suggest great whites or other large sharks occasionally attempt to prey on FKW's. Whether the opposite is true is yet to be seen, but as of now, there is no known evidence of FKW's preying on large sharks. BTW, here's a very informative research paper describing in some detail predatory and competitive interactions between dolphins and sharks. www.science.fau.edu/sharklab/courses/elasmobiology/readings/heithaus.pdf |
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