Saltwater Crocodile vs Great White Shark

[elosha11]

At some point, hopefully sooner than later, I'll respond more fully to various points raised in this thread on carnivora. But I did want to get the records straight on one point that's been referenced several times. In carnivora's shark/croc interaction thread and also on SW croc v. great white thread, in posts 628 and 630, benko2015 and the Roc use an recent account of a sw croc co-feeding with tiger sharks on a whale carcass as a sign that croc has no fear of swimming with multiple sharks. They also note that the croc appears to be subadult male, based on communication with Adam Britton. I will note this subadult shark actually seems a bit longer than the sharks, which indicates the tiger sharks are rather small to average size individuals as well.

The video benko2015 posted on post 628 is an excerpt and does not show the full footage. As I suggested earlier, the interaction shows neither animal had any fear of the other and were simply co-feeding with no need whatsoever to show aggression or territoriality toward the other. I said this video should not be used by anyone to demonstrate dominance, comfort level, or aggression one toward the other. It's simply predators minding their business and wisely focusing on the meal in front of them. I have now found more complete footage of the event, which clearly demonstrates that neither shark nor croc were intimidated or unnerved at all by the other. Click on the below facebook link for the exact moment of shark/croc interaction described below.

www.facebook.com/ABCKimberley/videos/10155897633042156/?t=52

also found at www.abc.net.au/news/2017-11-28/dead-kimberley-whale-provides-crocodile-and-shark-feeding-frenzy/9201590

In this complete footage, the makers of the tape note that neither animal was worried about the other, and this is conclusively born out by the footage shown at around the 50 second mark of the video, showing a tiger shark that looks to be substantially shorter than the crocodile calmly feeding on the whale directly alongside the larger croc. Neither animal shows any sign of fear or intimidation, as also backed up by the commentary first hand account of the video's maker. Now if I really wanted to twist this, I'd say this clearly shows that a smaller tiger shark has no fear of a larger croc, indicating the shark has some type of behavioral and/or predatory "advantage" over the croc. But that would be just as much folly as benko and the Roc's attempt to use this footage to imply some type of advantage for the croc.

In reality this footage shows two formidable predators feeding side by side with no more than a passing thought for the other. It does not demonstrate anything other than a passing feeding event between the species, where neither showed any apparent fear or deference toward the other. As I stated before, this video proves absolutely nothing other than that these predators are instinctively wise enough to focus on the feeding task at hand, rather than wasting energy trying to intimidate each other.

[elosha11]

Subadult/small adult tiger sharks on this video are not smaller than this subadult crocodile and at least have a comparable body mass.

I agree that predators for the most part ignored each other. But moment that you describe as "tiger shark that looks to be substantially shorter than the crocodile calmly feeding on the whale directly alongside the larger croc" was actually an interaction:
Quote:

Crocodile feeding behaviors were characterized into two categories: (1) horizontal bites where the crocodile floated on the surface of the water, which were common on pectoral fins and the fluke (Fig. 2a); and (2) vertical body positioning which included tearing and ripping, with use of the tail to generate pull and maintain body position, which focused on the fleshy rorquals of the whale (Fig. 2b). Behavior (2) on the rorquals occurred once, and during this event a tiger shark made brief contact with the crocodile, appearing to splash the water with its tail, likely in an effort to deter the crocodile from the region (ESM1, 0:28s). After this interaction, the shark quickly abandoned the region, after which the crocodile buried its head into the cavity of the whale, presumably in an effort to find more desirable pieces of flesh (ESM1).

www.researchgate.net/publication/323665644_Apex_predatory_sharks_and_crocodiles_simultaneously_scavenge_a_whale_carcass

The fact is that this subadult crocodile just swim considerable distance from shore to confidently fed on whale carcass, and do not see any threat in sharks (that will be present in such event in any case, by the way) at a significant distance from shore.

First, thanks for finding this research article, it's interesting, and I didn't know of its existence before now. I'm not sure, however, why you think these animals are the same size. The researchers clearly state they estimated that the 2 tiger sharks in the video were 3 meters and the crocodile was 4 meters. And it's quite clear looking at the video and pictures that the croc is noticeably longer than the sharks. In the brief interaction I cited on the video and described by the researchers, the croc looks at least a meter longer than the shark. Tiger sharks are considerably less robust than a great white shark at comparative lengths, and I'd say a crocodile that is a meter longer is probably also going to be somewhat heavier.

For the record, the researchers also state that after the shark abandoned the area after splashing the water, the crocodile continued to feed and then "Afterwards, the crocodile used its front legs to climb on to the pectoral fin where it remained for ~1min to either rest or avoid detection by tiger sharks."

It's really hard to know what was going in any of these animal's minds, but it seems quite farfetched to read much of anything into their behavior, either dominance or intimidation. They basically ignored each other.

[elosha11]

Creature386 -- FYI, I saw Benko's and the Roc's responses. I'll be posting my reply here hopefully in the next few days. Thanks again for continuing to post this debate on carnivora.

[creature386]

And this time, I'll hopefully post it just in time.

[Deleted]

Post it.

[creature386]

As long as I am active enough and can find it under the threads updated by you, I will do so.

[thalattoarchon]

I can vote for a croc if we are talking about weight parity or if a shark will be only a bit bigger than croc.

But very large great white sharks sometimes reach enormous sizes and are in other weight classes in comparison with any modern crocodilians.

Paper by Amorim et al. (2016) "Rare giants? A large female great white shark caught in Brazilian waters" describes 5.3 m long female great white shark with an estimated total body weight about 2.5 tons! But we know that great white sharks can reach 6 or even 7 meters in length so much bigger than this specimen. Wood (1983) describes 6.1 meter great white shark with 5.64 m girth (!!!):

He visually estimate the weight of this shark at around 3175 kg based on photo, but girth-TL based formula by "Biology of the White Shark, a Symposium, 1895. Sibley, Gretchen editor" give total body mass of this specimen at around 5750 kg:

Sorry, croc fans... I also love crocodiles & alligators. But we actually have Deinosuchus-sized opponent for poor saltwater croc. The shark is too big and massive. As far as I know the largest salties in theory can reach length of about 7 meters and weight around 1600-1700 kg. But there are no any real crocs with measered weight of more than 1114 kg. Great whites also can reach 7 meters in lenght and it's hard to imagine the maximum possible body mass and girth of a 7-meter shark...

Body girth really plays an important role in any fight of such large animals. You can even see that people often search the girth of the great white shark in Google:


I do not see how 1114 kg or even 1700 kg crocodile will have a match with a 5750 kg shark.

[theropod]

It’s actually not that hard to imagine at all. For some reason (I presume too much free time) people actually came up with no less than 6 regression equations to estimate the body mass of a shark at a given total length. The highest of these yields an estimated 3693kg for a 7m shark, average is 3399kg, the lowest 3096kg. Curiously absent from all of these were indications of the error bars, but I think we can get a rough idea from the deviations between the individual regressions.
But as to my knowledge, no reliably measured 7m great whites exist either.



Casey, John G.; Pratt, Harold L. 1985. Distribution of the White Shark, Carcharodon carcharias, in the Western North Atlantic. Memoirs of the Southern California Academy of Sciences, 9 (Biology of the White Shark, a Symposium.) pp. 2-14.
Gottfried, Michael D.; Compagno, Leonard J.V.; Bowman, S. Curtis. 1996. Size and Skeletal Anatomy of the Giant “Megatooth” Shark Carcharodon megalodon. In: Klimley, Peter A.; Ainley, David G.: Great White Sharks: the biology of Carcharodon carcharias. San Diego, pp. 55-66.
Kohler, Nancy E.; Casey, John G.; Turner, Patricia A. 1995. Length-Length and Length-Weight Relationships for 13 Shark Species from the Western North Atlantic. Fishery Bulletin, 93 pp. 412-418.
McClain, Craig R.; Balk, Meghan A.; Benfield, Mark C.; Branch, Trevor A.; Chen, Catherine; Cosgrove, James; Dove, Alistair D.M.; Gaskins, Lindsay C.; Helm, Rebecca R.; Hochberg, Frederick G.; Lee, Frank B.; Marshall, Andrea; McMurray, Steven E.; Schanche, Caroline; Stone, Shane N.; Thaler, Andrew D. 2015. Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. PeerJ, 3 (715) pp. 1-69.
Mollet, Henry F.; Cailliet, Gregor M. 1996. Using Allometry to Predict Body Mass from Linear Measurements of the White Shark. In: Klimley, Peter A.; Ainley, David G.: Great White Sharks: the biology of Carcharodon carcharias. San Diego, pp. 81-89.
Tricas, Timothy C.; McCosker, John E. 1984. Predatory Behaviour of the White Shark (Carcharodon carcharias) with notes on its biology. Proceedings of the California Academy of Sciences, 43 (14) pp. 221-234.

[thalattoarchon]

Sept 15, 2018 22:38:30 GMT 5 theropod said:

It’s actually not that hard to imagine at all. For some reason (I presume too much free time) people actually came up with no less than 6 regression equations to estimate the body mass of a shark at a given body mass. The highest of these yields an estimated 3693kg for a 7m shark, average is 3399kg, the lowest 3096kg. Curiously absent from all of these were indications of the error bars, but I think we can get a rough idea of from the deviations between these regressions.
But as to my knowledge, no reliably measured 7m great whites exist either.

As far as I know, when great white sharks stops to grow in length they continues to grow in width. Thus regressions from smaller sharks do not necessarily allow to predict the body mass of largest specimens. You can use the mentioned large 5.3 meter and 6.1 meter individuals with estimated body mass for scaling to 7 meters according to the square-cube law.
6.8 meters seems to be the possible maximum size for this species: www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharodon-carcharias/

And even if we use verified body masses the great white shark still will be 3+ times heavier than the poor croc...

[theropod]

That is sort of the point of having a regression equation in the first place instead of just scaling up isometrically. They do test whether shark mass grows with positive allometry by including individuals of various sizes.

For example the sizes of the sharks in McClain et al.’s dataset range from 35cm to over 7m (though the reliability of the largest one has been questioned previously). Interesting enough, they found that mass scaled isometrically (i.e. ~TL^3.0). As you can see from the results, there is some considerable variation between the scaling relationships found by the various regressions, with some giving significantly higher results than others for the larger sharks (the highest scaling exponent is 3.17 from Gottfried et al. 1996). The upper end estimate (Kohler et al.) does in fact take into account the shark growing significantly bulkier at larger sizes.

Whether that trend is real or not is another question, but positive allometry of body mass is certainly not unusual. In any case, with the huge amount of individual variation, it can be very misleading to scale isometrically from a single specimen. And using a weight that was not actually measured but rather guesstimated based on a photo, as in your example, is even worse. Do you seriously think that that kind of weight estimate is reliable? In that case I would suggest performing a little experiment as to how closely people can estimate the mass of various objects just by looking at them, and see how reliable those figures are.

I don’t doubt that the shark is three times the weight of the crocodile at all. Matter of fact, I wrote exactly that in the very first post on this thread. Nor for that matter do I doubt some great whites are incredibly bulky, some 6m sharks mass over 3t. And some don’t, there is a significant breadth of variation and not all of it is size-related, hence we cannot automatically assume the longest shark on record was also the most robust, just because we can find a relatively short specimen that is massively heavy.

My point was merely that we can, in fact, have a fairly good idea what weight a 7m shark is most likely to have.

[thalattoarchon]

Sept 16, 2018 0:38:46 GMT 5 theropod said:

That is sort of the point of having a regression equation in the first place instead of just scaling up isometrically. They do test whether shark mass grows with positive allometry by including individuals of various sizes.

For example the sizes of the sharks in McClain et al.’s dataset range from 35cm to over 7m (though the reliability of the largest one has been questioned previously). Interesting enough, they found that mass scaled isometrically (i.e. ~TL^3.0). As you can see from the results, there is some considerable variation between the scaling relationships found by the various regressions, with some giving significantly higher results than others for the larger sharks (the highest scaling exponent is 3.17 from Gottfried et al. 1996). The upper end estimate (Kohler et al.) does in fact take into account the shark growing significantly bulkier at larger sizes.

Whether that trend is real or not is another question, but positive allometry of body mass is certainly not unusual. In any case, with the huge amount of individual variation, it can be very misleading to scale isometrically from a single specimen. And using a weight that was not actually measured but rather guesstimated based on a photo, as in your example, is even worse. Do you seriously think that that kind of weight estimate is reliable? In that case I would suggest performing a little experiment as to how closely people can estimate the mass of various objects just by looking at them, and see how reliable those figures are.

I don’t doubt that the shark is three times the weight of the crocodile at all. Matter of fact, I wrote exactly that in the very first post on this thread. Nor for that matter do I doubt some great whites are incredibly bulky, some 6m sharks mass over 3t. And some don’t, there is a significant breadth of variation and not all of it is size-related, hence we cannot automatically assume the longest shark on record was also the most robust, just because we can find a relatively short specimen that is massively heavy.

My point was merely that we can, in fact, have a fairlwhich allowed them to more accurately assess the size of the shark than just visually.y good idea what weight a 7m shark is most likely to have.

But how much of the large 5+ meter long great white sharks are included in this regressions? I think that we need to have measurements of solid number of large sharks with known weight-total lenght ratio to have an reliable data about the average expected weight for largest individuals. And in the ideal this data must be associated with the age and preserved growth rates of shark which can not be available for now. Even for crocs regressions that based on the measurements of smaller individuals compiled with the allometric growth still underestimate the mass of the largest individuals (Grigg, 2015).

Amorim et al. (2016) have several measurements which allowed them to more accurately estemate the body mass of this shark than just visually:

The GWS was captured 30 nautical miles off the coast (around
40 m depth) off Bom Abrigo Island, Cananeia, Southern Brazil
(25°08’08^S, 47°15’05^W) on December 8th, 1992 (Figs. 1
and 2). The captured shark was a female of 530 cm TL (503 cm
FL), with an estimated total body weight of 2.5 tons (Fig. 2);
detailed morphometric measurements are included in Table 1.
The perimeter of the jaw measured 106.5 cm and the highest
superior teeth measured 48.3 mm. The dental formula was 25/
22 = superior 6–7:7–5 and inferior 5–6:6–5. The mass of the
internal organs were as follows: liver 674 kg, stomach 200 kg,
intestine valve 16 kg, uterus 13 kg, ovary 12 kg, pancreas 3 kg,
heart 3 kg and spleen 1.8 kg. The estimated hepatic somatic
index (HSI) was 27% (Fig. 3). The shark was not pregnant, and
uterus condition did not show evidence of recent parturition.
Healed bite marks were present on the left pectoral fin and
flank, a possible indication of prior copulatory behavior.

[theropod]

Well, the plots are all there in the papers for you to take a look at, many of them (and not necessarily the ones yielding the highest results) do include a large number of large specimens.

McClain et al.:


Casey & Pratt:


Kohler et al.:

(the one yielding the highest results at the sizes we are talking about seems to be the one including the fewest large sharks, curious…)

Tricas & McCosker:

[thalattoarchon]

It seems that the Tricas & McCosker regression has the largest number of relatively large specimens. But number of specimens with extremely high weight (addition of two specimens measured 530 cm 2500 kg and 610 cm 5750 kg respectively could even change the regression line) still seems limited and 4+ meter sharks less than 500 kg in weight look as very problematic individuals...

[dinosauria101]

Excellent classic! I'd favor the shark, as it seems to have the deadlier bite and can do more damage to the croc with it tan vice versa.

[rock]

in deep ocean water the shark wins , in shallow ocean water , the crocodile would win , to me the winner depends on where they fight