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Post by sam1 on Aug 7, 2018 0:42:51 GMT 5
It doesn't make the figure true, but it adds a lot more weight to the whole picture. It's just not the same as some anecdotal testament, as you imply. Also keep in mind that the whale hit the ship twice.. after the first hit he floated in close proximity for a while, and then came back to finish the ship. Given the context and the shock, I would take such a statement with even more salt. The legendary GWS nicknamed submarine was witnessed several times in the 70's, including by a marine biologist, this doesn't make the claim of 8-9 m anymore true. A GWS was observed in the Dakar harbour by a marine biologist that was according to him 9 m (Maddalena 2001). The French paleontologist Jean-Loup Welcomme, who collects sharks teeth, told me the largest megalodon he has seen was in a Museum in Angers and was, in vertical height, 22 cm. George Blasing reported to have seen a broken tooth, the root only, the was twice larger than the same part in a 5 inches tooth he possessed. Despite these claims coming from scientists or educated people and being modern accounts, unlike those of the Essex which are 2 centuries old, we have to take these claims with extreme caution. Well, let's look a bit at the context. The context was that the people involved in the estimate were actually the people with the most first hand experience with the subject at hand..a seasoned sperm whale butchers that knew these whales literally from inside out. If anyone could tell the size of the whale, it was them. And the "shock" you speak of..you think 25 of hose people used to battling sperm whale bulls out in the tiny boats were in such shock after the initial hit, with the whale floating next to the still standing ship? Such shock that all of them were hallucinating about whale and a ship being the same length? As for the giant GWS sightings, let me just put it this way..if there is a GWS tooth or a vertebra that could possibly scale to a 9-10m animal, then there is some credibility to those claims. Given that GWS grow throughout their lives, I would like to imagine that every once in a century or so a truly giant great white happens..just give me some supporting material. |
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Post by Grey on Aug 7, 2018 2:35:08 GMT 5
When an impressive animal is in sight, anyone, whalers or scientists, can overstate its size.
If there is someone to trust about the whale size, before any two centuries old whalers claims, it's the scientists.
All the other examples I've given come from people just as well used as it, I refered to marine biologists here.
There is no more evidence for a 9 m modern GWS than for a 26 m Physeter.
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Post by theropod on Aug 10, 2018 3:43:59 GMT 5
 I have wanted to post this sooner, but I was pretty swamped with work up until about 2h ago. So I may have been a little too quick dismissing the positively allometric scaling of jaw length. Log-transforming the data, we actually do get a 95% confidence interval for the slope/exponent that’s between 0.61 and 0.94, as well as a marginally weaker correlation (R^2 0.09 and p=0.335) of the residuals. So this model seems to be a slightly better fit than the linear one. Since we’re extrapolating quite a bit, I think it’s anyone’s guess which is the more likely, since there’s only a pretty small difference in how well they explain the data. It would certainly be interesting to test this with a bigger sample though, so if you have any datasets of Physeter measurements lying around that you somehow haven’t felt the need to share yet, let me know. The estimates are not massively different though, however interestingly the log-transformed model gives a wider range of estimates. point estimate 2125.923 50% PI: 2007.048 to 2251.839 75% PI: 1922.815 to 2350.486 95% PI: 1770.037 to 2553.364 And finally, for those of us who want to believe this jaw could be evidence of a 28m sperm whale: 99% PI 1638.232 to 2758.798 The probability of this 5.5m jaw coming from a >27.6m bull is less than 0.5%, it’s just as likely that it was below 16.4m, although those are both extremely improbable. Honestly I don’t find estimates that are this poorly supported very interesting at all. A fairly realistic range is probably 20.1-22.5m lm(log(tl)~log(jaw), data=malephys)->logmaleph
confint(maleph)
exp(predict.lm(logmaleph, nantucket, interval="prediction", level=.95))
exp(predict.lm(logmaleph, nantucket, interval="prediction", level=.75))
exp(predict.lm(logmaleph, nantucket, interval="prediction", level=.75))
plot(data=malephys, tl~jaw, xlim=c(100,600), ylim=c(800,3000), ylab="Total Length (cm)", xlab="Mandible Length (cm)")
curve(exp(coef(logmaleph)[1])*x^coef(logmaleph)[2], add=T)
predict.lm(logmaleph, data.frame(jaw=c(seq(100,600,50))), interval="prediction", level=0.95)->logphys_preds
lines(c(seq(100,600,50)), exp(logphys_preds[,2]), col="blue")
lines(c(seq(100,600,50)), exp(logphys_preds[,3]), col="blue")
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Post by prehistorican on Apr 12, 2019 6:51:45 GMT 5
I still don't understand how heavy the 20.3m/largest recorded sperm whale was. Was it really 57 tonnes? seems too light.
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Post by Grey on Apr 12, 2019 21:17:33 GMT 5
20.5 m; 88 tonnes.
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Post by sam1 on Apr 13, 2019 0:57:02 GMT 5
I believe the Essex destroyer was at least a 24m specimen.
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Post by theropod on Apr 13, 2019 1:01:29 GMT 5
But we are not here to discuss our beliefs, at least not in the zoological discussion area.
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Post by elosha11 on Apr 13, 2019 1:26:05 GMT 5
But we are not here to discuss our beliefs, at least not in the zoological discussion area. Theropod,, Likely, Sam1 was just expressing the familiar and relatively informal grammatical usage of "I believe" rather than some affirmative fact completely established in his mind. I could be wrong. I'm not saying he doesn't think the Essex whale is that large, but the "belief" usage in his sentence is not likely as dogmatic as the literal usage implies. There's a difference of spectrum - for instance - when a true believer states, "I believe in the divinity of Jesus Christ" vs. me stating, "I believe it rained last Thursday." The former asserts a far stronger position, while the latter is a more informal usage expressing an opinion, but often, in the speaker's mind, also showing a certain degree of hedging or uncertainty., I'm not just grammatically nitpicking here. This is why it's often so hard to truly interpret the written word, without such helpful things as voice intonation, which sometimes leads to confusion and frustration between the persons communicating. |
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Post by theropod on Apr 13, 2019 2:50:35 GMT 5
elosha11 I am well aware of all that. My point was not to nitpick on linguistic grounds, nor was it literally conflating sam's statement with a religious belief. I'm certain sam does not believe in that statement in a fanatical kind of way, because I'm sure he agrees that it is not a fact. But even opinions require reasons. What I was getting at is the lack of explanation or evidence to go with it. Sam may or may not have good reasons for having the opinion that the whale was that size, but if he does, then he should share them. Just uttering opinions without clarifying the reasons for those opinions just isn't good scientific practice, that is indeed closer to the practice in theology, where certain opinions, called beliefs, are taken for granted without requiring evidence. Which I'm sure isn't what we want, because it would soon devolve into all people just stating their gut feelings, with no one feeling compelled to give any arguments. A belief is simply an opinion that someone doesn't think they are required to give evidence for. That may be fine for sone kinds of personal belief, but it certainly isn't in science. So if sam thinks the whale that sunk the essex was 24m long, what I'd be more interested in is why he thinks that, not that he thinks that.
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Post by elosha11 on Apr 13, 2019 3:19:22 GMT 5
Yes, I get what you're saying. What I'm suggesting is that such terms as "I believe" even on a board such as this, can have many interpretations. And I understand that you would like his reasons and evidence for the Essex whale's size, so I think a more constructive way is to simply ask for the evidence directly rather than obliquely through the questioning of language semantics. My guess is Sam1 probably has multiple reasons, but was simply writing a quick post which he could later expand upon.
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Post by prehistorican on Apr 13, 2019 3:28:19 GMT 5
I understand Mocha Dick the sperm whale was about 21.34m but any larger sperm whales? I've heard of 24m which I believe is the possible maximum but I'm not sure.
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Post by sam1 on Apr 13, 2019 3:45:04 GMT 5
elosha11 I am well aware of all that. My point was not to nitpick on linguistic grounds, nor was it literally conflating sam's statement with a religious belief. I'm certain sam does not believe in that statement in a fanatical kind of way, because I'm sure he agrees that it is not a fact. But even opinions require reasons. What I was getting at is the lack of explanation or evidence to go with it. Sam may or may not have good reasons for having the opinion that the whale was that size, but if he does, then he should share them. Just uttering opinions without clarifying the reasons for those opinions just isn't good scientific practice, that is indeed closer to the practice in theology, where certain opinions, called beliefs, are taken for granted without requiring evidence. Which I'm sure isn't what we want, because it would soon devolve into all people just stating their gut feelings, with no one feeling compelled to give any arguments. A belief is simply an opinion that someone doesn't think they are required to give evidence for. That may be fine for sone kinds of personal belief, but it certainly isn't in science. So if sam thinks the whale that sunk the essex was 24m long, what I'd be more interested in is why he thinks that, not that he thinks that. I didn't elaborate on my statement simply because I also believe you all know that it's based on the eyewitness descriptions. We discussed that already. The survivors were stating that the whale was as long as the ship. I *believe* that their testimonies weren't all deluded exaggerations, you obviously disagree and that's all there is to be said about. |
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Post by Grey on Apr 13, 2019 4:08:34 GMT 5
The Essex specimen was reported 24 m originally but sperm whale expert Hal Whitehead doubts about it.
The scientific litterature considers it was 80 tonnes, monstrous and more plausible.
Or a 24 m specimen could be not excessively bulky. I dont believe any true carnivore, even squid-eater to have exceeded 100 tonnes.
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