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Post by sam1 on Jul 19, 2018 2:37:44 GMT 5
Nothing I stated is implied, it is factual. Ironically it is you who now tries to imply the factual mobility advantage should be evidenced by "domination" in face to face fights at parity. Again, my point is that whales are more impressive mobility wise. Let's break it down. Sperm whales are faster than sharks of similar size. Top speed claims range up to 40km/h, with reliably scientifically measured and confirmed 30km/h. Sustained bursts(up to over 3 minutes and over 400 meters) typically at great depths (around 900m). more here: www.int-res.com/abstracts/meps/v444/p289-301/On top of superior speed, Sperm whales can maneuver while being stationary. Sharks can't. Sperm whales can swim upside down. Sharks cant. Sperm whales can roll around their axis during stationary and forward motion. Sharks can't. Sperm whales can balance their motion so that they remain stationary even while swinging the flukes in forward motion manner (rosette formation). These are factual arguments about mobility of the respective animals. Your argument is "but but they should then dominate in fights so that means their mobility is not superior". |
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Post by theropod on Jul 19, 2018 2:55:17 GMT 5
Grey Thanks, that’s all I asked for. I just don’t have the time nowadays to always go searching for papers on nothing but the name of the lead author, it’s just so much easier if we all provide at least a link or the title of the studies we refer to, so that they are quick to find for someone who might not already know them. I do recall previous suggestions that C. megalodon should have been at an advantage at attaining larger sizes compared to other predators because of its supposedly lower metabolic rate. So it seems Ferrón et al. suggest the opposite, that a higher metabolic level (or metabolic rate adjusted for size) allows active predatory lifestyles at larger sizes. About activity level, yes they do show Livyatan at a higher metabolic rate, but it seems like there is no quantitative methodology behind that estimate, or am I missing something here? And it has to be kept in mind that specific metabolic rate tends to decrease at larger sizes anyway, so the (doubtful) assumption that C. megalodon was larger than L. melvillei (looks like the sizes are just based on total length figures) is a major factor. C. megalodon is shown at a similar metabolic level (i.e. metabolism adjusted for the impact of body size) to the fin and blue whales, which are fully endothermic (though admittedly filter-feeders). Livyatan is shown one level above that, where basically all odontocetes and other toothed cetaceans are shown, including sperm whales. But if those are really more active than the former, it doesn’t seem to show when comparing sperm whales to rorquals or humpback whales. This is certainly an interesting observation, although some of the assumptions made for illustrating it (e.g. "mesothermic" plesiosaurs, realistically derived plesiosaurs should probably be right at the top of that diagram) are probably wrong. But I don’t see direct evidence for the relative metabolic rates of Livyatan and megalodon in there, only a proposed principle of the effects of metabolism on gigantism in active predators.
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Post by Grey on Jul 19, 2018 3:08:10 GMT 5
Sam1, no, I never meant their mobility is not superior but direct observation shows it is at best undecisive in a direct match up against a shark of similar size.
I repeat there is a lack of data about the max burst speed of basking and whale sharks.
Theropod, I recall Bretton Kent being quite agreed with Ferrón conclusions, at least regarding megalodon. I don't think this contradicts the notion that the predator with slightly lower metabolic requirements will have advantage at growing larger.
The body mass figures are clearly based on the length figures and presumably on the mass figures when available.
So, Ferrón should certainly revise his data for the marine reptiles...
His latest paper was highly interesting too, using the metabolic constraints he estimated the biggest Leedsichthys to reach ~45 tonnes.
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Post by theropod on Jul 19, 2018 3:12:00 GMT 5
4t basking sharks can leap entirely out of the water, but so can 40t humpback whales. Could a 40t shark do it? That’s not testable without a living 40t shark willing to do circus tricks for us. The more relevant question would be how basking sharks compare to similar-sized killer whales in terms of mobility. That it is capable of a feat even a cetacean 10 times its own size can also accomplish doesn’t really prove its exceptional mobility.
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Post by sam1 on Jul 19, 2018 3:15:52 GMT 5
p.s. regarding the speed of sharks and whales, one interesting detail never gets noticed or mentioned (I mentioned it once on carnivora IIRC). It is that shark's pectoral fins are static and produce drag while whales simply fold their fins during a fast swim.
Granted, some sharks, notably Mako shark, seem to be able to overcome this handicap, but the significance of drag increases in relation to size.
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Post by theropod on Jul 19, 2018 3:26:36 GMT 5
Theropod, I recall Bretton Kent being quite agreed with Ferrón conclusions, at least regarding megalodon. I don't think this contradicts the notion that the predator with slightly lower metabolic requirements will have advantage at growing larger. Well, according to Ferrón et al, it does contradict it: The relationship between body size and metabolic rate has repeat- edly been studied with body size considered as an independent variable. However, Makarieva et al. (2005a, 2005b, 2006) have recently suggested that metabolic rate could be an important con-
straining factor of the maximum body size of animals and plants. Following this idea, our proposal considers metabolic rate as a key determinant factor for body size, activity level and feeding strat- egies in aquatic vertebrates. Then, given that mass-specific meta- bolic rate decreases when the body mass increases, we hypothesize that active predation is unaffordable once a given body mass is reached and only less active lifestyles and feeding strategies (e.g. filter feeding, scavenging, etc.) are physiologically sustainable above this size. However, this limit is reached at different body
sizes depending on the thermoregulatory strategy and, ultimately,
metabolic level; endothermic predators can reach bigger potential
body sizes than their ectothermic analogues. But like so many things, this is a very generalized trend and does not automatically dictate that an animal with a higher metabolic level will always grow bigger than one with a lower rate, just because it can. That would only be true if the animals were assumed to reach the maximum size that was physiologically possible. Plesiosaurs are the best example of that, a multi-ton or at least multi-100kg plesiosaur with the metabolic rate of a chicken is certainly hugely impressive, and from that alone they would be expected to reach larger sizes than sharks or mammals, but no known plesiosaurs reach, let alone exceed, the size of C. megalodon or L. melvillei. So obviously their size was constrained by other, presumably non-physiological factors. And that argument can of course be made for any animal, so in the end the actual direct fossil evidence is what allows us to make size estimates, not theoretical physiological restrictions that are probably very hard to reliably calibrate anyway. Could you link that paper too? I’m inherently sceptical of theoretical predictions of maximum size which are not based on real fossils, but it will be interesting nonetheless. |
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Post by sam1 on Jul 19, 2018 11:53:14 GMT 5
Sam1, no, I never meant their mobility is not superior but direct observation shows it is at best undecisive in a direct match up against a shark of similar size. I repeat there is a lack of data about the max burst speed of basking and whale sharks. You were very clear on that opinion, sorry. "Simply said, the mobility of a 9-12 m cow sperm whale doesn't appear more impressive to me than that of a filter feeder basking or whale shark of similar size." And you were corrected , so just accept it and move on. "They can breach" is no argument on largest shark rivaling whales in terms of speed. You need evidence. The literature typically states that filer feeder sharks are slow, and maximum speed for a whale shark is stated at 14km/h. |
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Post by theropod on Jul 19, 2018 12:01:50 GMT 5
sam1: Firstly, I would suggest that top speed is rather irrelevant here, maneuverability is much more interesting. Secondly, top speed of a large marine animal is very difficult to measure, so pretty much any speed figure has to be taken with a grain of salt. Case in point, nobody seems to know the top speed of the great white shark, although that’s a matter that certainly should have received above-average attention. Who knows whether your speed figure for the whale shark (source?) really represents the maximum the species can reach?
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Post by sam1 on Jul 19, 2018 15:29:57 GMT 5
I provided reliably measured, scientifically researched speed of a Sperm Whale.
Unless Ted can provide the same in respect of the sharks, the available data says that SW are more than twice faster than whale sharks.
And some subjective suggestion that 100% more speed is irrelevant, holds no relevance honestly.
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Post by sam1 on Jul 19, 2018 15:52:11 GMT 5
..alright, here's some simple hypothetical scenario under the hypotherical assumption that Livyatan was significantly faster than a Megalodon.
The two animals approach each other head on. They both accelerate and clash. The whale accelerates at higher speed and carries more momentum and more force.(let's say a force of 50 tons moving at 30km/h)
They collide in a tremendous brush while the whale rolls sideways to protect its underside and eyes, using its forehead as a battering ram. The shark is bumped off and slightly stunned while the whale bruises by.
The whale deaccelerates quickly, rotates and bends, looking for the shark, while the shark picks itself up and tries to dive down. The whale charges again but this time the shark is in for the taking. He catches up with it and rams it from side, then grabs the shark's pectoral fin with its jaws.
Tremendous struggle unfolds but the whale is built to grip and resist tremendous force.
It tears the Meg's entire fin off.
And the fight is basically over.
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Post by Grey on Jul 19, 2018 18:39:47 GMT 5
For some reasons, the scenario above doesn't seem to occure between similar-sized odontocetes and macropredatory sharks today.
Regarding the sharks speed, theropod recalled that even in the white shark the top figures are uncertain. Let alone the larger whale sharks and basking sharks. Despite their slow moving habits, they share a remarkably athletic body shape and efficient caudal for strong and efficient swim. There is circumstencial evidence that they are tonic and fast animals when they need to.
Regarding megalodon speed, Jacoby et al. 2015 estimated that a 48 tonnes individual had a cruising speed of 5 meters per second, twice as much as a 1 tonne white shark and equivalent to the cruising speed of a fin whale.
Ferrón et al. 2017 estimates a 18 m individual had a burst speed, being mesothermic, of 37 kph.
That's fairly equivalent to what has been measured for the sperm whale.
This invalidates the previous scenario at least in the speed department.
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Post by prehistorican on Jul 19, 2018 20:10:54 GMT 5
SIGNIFICANTLY FASTER?  Great whites can reach 40.23kmh, but acknowledged they can reach 56kmh in a straight line. Bottlenose dolphins only reach 37kmh. Grey, I believe that the Jacobson cruise speed was an error and actually around 5kmh. This doesn't necessarily mean the shark was slower than Livaytan per se. Bottnose dolphins have a faster cruise speed but a slower top speed (half the size of a white shark as well) than a great white shark. In fact this means that a large portion of Megalodons muscles were probably pure type 2b fibers, meaning a burst speed probably exceeding even a fin whale at burst speed, maybe even by a large margin (giving a slight credence to the scaled white shark speed). Let's go with a "Sam1" absolutely 100% accurate scenario shall we? (Note: This is sarcasm, only those without common sense and intelligence and nonbias will take this seriously) The shark and whale charge head on, just as the Livyatan braces for a ram, the shark uses its turn radius advantage to dive underneath the whale. The stunned whale is unable to do much now, at full speed turning or slowing down is extremely difficult. As the shark dives underneath the whale, it slams its gigantic jaws into the mid-tail section of there Livyatan and rips out a multi-ton chunk of flesh+blubber. A bloody cloud of red spills out into the nearby water, with flesh and caudal vertebrae. Immobilized, the whale is hopeless. Just so be safe, the shark turns around and does a massive ram charges at the immobilized Livyatan. This cracks the ribs and severly weakens the whale, as now it has internal bleeding. Turning it's head toward the midsection of the whale, the shark bites down crunching through its opponent's ribs and spine like butter. Throwing up a pinkish cloud of blood and stomach contents into the water, organs coming out from the crushed open ribecage. Tearing the Livyatan to pieces for easier feeding, the shark feeds on its dead rivals carcass as a cloud of blood completely obscures both animals. |
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Post by sam1 on Jul 19, 2018 22:57:54 GMT 5
Gotta admit, that gave me a good laugh.
Teeth, blood and gore obsessed meg fanboy at its best. You delivered gloriously.
Utter fantasy BS with shark's reactions that make no sense.
Just before the clash, it uses its superior turning ratio to dive underneath the whale?! 😅
And then while being underneath, it somehow manages to rip a huge chunk of flesh from a *stunned* whale that's above him!! 😄 How? Did he rolled up, whale style?!?
And the whale is stunned from what?
Damn I'm literally laughing again while typing this nonsense.
*Ted.
We don't know how fast Meg and Livy were, that's why I stated that my scenario is a hypothetical one. Just in order to illustrate to Theropod that greater speed is all but irrelevant.
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Post by theropod on Jul 19, 2018 23:33:10 GMT 5
sam1 : Yes, you did. What you did not do was to provide a reliable, scientific source for your claims about whale sharks. And as I already explained, we can’t automatically assume the fastest speed we have recorded to be the fastest speed the animal is capable of, there are many reasons why this might not be the case. Top speed figures for animals are notoriously hard to pinpoint, especially in rare, aquatic animals that may not be compelled to swim as fast as they can when someone watches. So this observation is of limited importance, even if that is the highest speed we can find for whale sharks in the literature. Even if sperm whales were 100% faster though, that does not mean you can automatically equate that to this scenario. A much more (ecologically and morphologically) relevant comparison would be orca vs great white, and I don’t see reliable speed figures for these two diverging too much (45m/h in Ford et al. 2005, and the frequently cited 40km/h for great whites, although higher figures are commonplace too). Again though, it would help to find a reliably documented speed figure for the great white shark. But it makes a lot more sense that two predators that take the same prey (unlike sperm whale and whale shark), are similar in size and bulk, and fill a similar ecological role, are also capable of attaining similar speeds. That’s what we see in orcas and great whites. Of course that comes with the same caveat, perhaps one or both can actually swim much faster, but have not been reliably recorded doing so. But in the absence of other evidence, and the presence of evidence that these predators are capable of similar feats of athleticism at similar sizes, it’s most parsimonious to assume they are similarly fast. This would of course likely scale up to Livyatan and megalodon as well. And no, I don’t think top speed will be very relevant here. The question is not who can outswim whom in a straight line. Accelleration on the other hand may play a much bigger role, because that affects how much of their top speed these animals could actually utilise given the short times available to accellerate and the frequent changes of direction necessitated by a fight. I have already acknowledged long before you even came to this forum that Livyatan likely had far superior ramming ability, not due to any hypothetical top speed advantage as you imply, but because it has a skull adapted for that behaviour (most odontocetes do, physeteroids especially). The problem with ramming is not to generate enough momentum, any 50t animal traveling at even modest speeds will easily carry enough momentum to cause major injuries if applied properly. It’s just that the whale has the adaptions to transmit that impact energy effectively and safely, the shark does not, in fact there’s a good chance a megalodon colliding with a Livyatan as described by prehistorican would be more fatal to the shark than to the whale. Assume an unelastic collision between the two:
50t shark traveling at 37km/h, hitting a similar-sized whale. With total momentum being preserved, that means both parties would have half the initial speed afterwards (this is assuming they both would continue in the direction of the ram as one. This is not completely realistic as there would be some elasticity involved, but its probably a conservative approximation).
Speed decreases by half. Let’s say the distance over which this deceleration takes place is 1m (I think I’m being pretty generous here).
So we’ve got a change in momentum of 50000kg*10.3ms⁻¹*.5=256944 kgms⁻¹ over a time (deceleration distance/average speed) of 1.25 m/(10.3 ms⁻¹*.75)=0.129s, meaning the average force would be 1980 kN or 198t (and peak forces might well be much higher than that). Transmitted by a cartilaginous chondocranium with no adaptions to resist impact forces, I think I rather see the megalodon being the severely injured party here. I fail to see where else in your imaginative scenario top speed is so important. Basically replace top speed with acceleration, and we might be getting somewhere. Grey : What is the evidence for fast swimming speeds in whale sharks? Jacoby et al. published a correction in 2016, 5ms⁻¹ is an error, the actual figure is 1.3ms⁻¹. I’ve posted this earlier when discussing with prehistorican. Ferrón’s burst speed estimate is interesting (and seems reasonable), but it’s important to keep in mind that it is nothing but a general estimate for an endothermic fish of its body length, with huge error bars (fig. 2, D). So that’s not direct evidence of how fast C. megalodon, or even a shark that size, was so much as a generalized trend of how fast an endothermic "fish" that size might swim. Imagine for a moment estimating the speed of a terrestrial animal from regressing speed against body length in all terrestrial animals with similar metabolism… prehistorican : (just to be sure: You were just parodying, right?) Do you happen to know the source for the 40km/h GWS speed (and while we’re at it, the bottlenose dolphin speed)? If white muscle in sharks really confers such an advantage in mobility, then I’m still waiting for the explanation as to why Great whites don’t seem to outperform Killer whales or False killer whales at similar sizes.
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Post by prehistorican on Jul 19, 2018 23:38:39 GMT 5
Gotta admit, that gave me a good laugh. Teeth, blood and gore obsessed meg fanboy at its best. You delivered gloriously. Utter fantasy BS with shark's reactions that make no sense. Just before the clash, it uses its superior turning ratio to dive underneath the whale?! 😅 And then while being underneath, it somehow manages to rip a huge chunk of flesh from a *stunned* whale that's above him!! 😄 How? Did he rolled up, whale style?!? And the whale is stunned from what? Damn I'm literally laughing again while typing this nonsense. *Ted. We don't know how fast Meg and Livy were, that's why I stated that my scenario is a hypothetical one. Just in order to illustrate to Theropod that greater speed is all but irrelevant. Yours did too. Honestly that wasn't even supposed to be realistic whatsoever as much as your scenario. That is why I named it "Sam1 scenario" since it seems to be just as much as reliable as your infallibly incorrect assume that of the scenario. How? What? Same questions go FOR YOUR SCENARIO AS WELL. I COPIED YOUR STYLE AND INNACURACY. Dear god the irony you Livyatan fanboys, just need a Livyatan monster machine. You stupid piece of scenario, in which two animals would most likely not confront each other head on for the sake of trying to kill each other is utter fanboyish at its finest. Your nonsense is pretty much your scenario and my scenario. The thing is, I am not serious about my satirical scenario where you take it as literal. Quite amazing indeed. |
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Great whites can reach 40.23kmh, but acknowledged they can reach 56kmh in a straight line. Bottlenose dolphins only reach 37kmh.