Has anyone here ever read the book Meg? (I forget the name of the author) the idea was of a prehistoric shark 40 feet long living in the marianis trench. considering how little of the deep oceasn we have actually explored ( we have actually physically explored more of the moon) The dea is possible, but is it pluasible?

I've not read the book but seen plenty about various big beasties down there. All are possible but plausable?? well yes and no.
I agree that with the amount of space down there unknown to us. (by this i don't mean that we have mapped using satalittes, but the amount we havent dived into)

This leaves many possibilties, however the issue comes when you hear all these stories about a big whatever somewhere. My problem is that its always "an", "a", "one of". As we all know a species annot live without reproducing and for reproduction to be successful, a minimum sized gene pool has to exist.
This is fine in the cases of Architeuthis as there have been sightings all over of many different specimins, showing it to be a stable species.
Since the concept of one creature surviving a few thousand years is beyond my scope of belief, then the only option left is for it to be an entire species.

Here's where i develop some slight problems, when you look again at giant squids they fit into the ecosystem well. They're big eat stuff like other squid do and get eaten themselves (sperm whales a prime predator).
The problem arrises when you talk about something of this size that is a top class predator.... I'm no biologist, but i think it's safe to say a 40ft shark requires a massive amount of food to live off. Thereby meaning a whole population of them would require even more.

So considering that without a population it is pretty impossible then, back to the original question, slightly altered.
40ft sharks living in and around the marianis trench possible? yes. plausable? sorry but i', gona go with no. More likely a few large specimin sharks have been seen by saliors etc who forgot to take into account water depth distortion.

The author is Steve Alten. He wrote two novels about megalodon sharks, Meg & The Trench. Both were good summer reads, but plausible? No, for the reasons mentioned in feygan's post.

Thats what I figured but it was a damn good read.

a few dead bodies is all that has ever been found in conection with the giant squid no living squid has EVER been seen and NO adult dead or alive has ever been found so Id say there could easly be manny larger sharks and other animals that we havent descovered yet and go on to say theres also a good possibilty for larger land animals to still be descovered as well.
The amazon rain forest is a huge place and theres still areas even today were no man has ever set foot.

Originally posted by Simcity4Rushour
a few dead bodies is all that has ever been found in conection with the giant squid no living squid has EVER been seen and NO adult dead or alive has ever been found so Id say there could easly be manny larger sharks and other animals that we havent descovered yet and go on to say theres also a good possibilty for larger land animals to still be descovered as well.
The amazon rain forest is a huge place and theres still areas even today were no man has ever set foot.

Very true however discint "squid like" markings have been found on sperm whales, with the exception of them being oversized. Since it's know sperm whales do eat squid, then this points to either a large prey item tryig to fight back, or some other undiscovered creature of large size involved in a conflict. It would also have to have almost identical sucker "footprints" as squid. So whilst none alive have been caught, i think theres enough evidence to prove their existence.

I never said that giant squids wernt real what I was pointing out is even though we KNOW for a fact the excist we have never seen a live one .
This animal is though to possibly grow to 100 feet so its quit possible theres plently of animals we havent found yet in the DEEP .

Originally posted by Simcity4Rushour
I never said that giant squids wernt real what I was pointing out is even though we KNOW for a fact the excist we have never seen a live one .
This animal is though to possibly grow to 100 feet so its quit possible theres plently of animals we havent found yet in the DEEP .

What feygan was saying was that we have coroborating proof for giant squids, so even if no bodies were ever found on the shore, we could make a safe guess that something large and squidlike lived in the deeps inhabited by sperm whales. Since the scars on the sperm whales seem to be exact, if larger, versions of squid suckers, it'd be safe to say that it's a giant form of squid.

We do not have whales' (or other critters') carcasses with giant "shark-like" scars on them, so the best guess we can give is that megalodon no longer exist. If we start seeing non-fossilized shark teeth of immense size, then it's time to re-evaluate things.

Ok been doing a little more research on this to try and give a more substanced argument.

So first things first we need to take a look at the minimum required number of individuals for a species to survive. Since we all know that without genetic diversity, inbreeding and ultimately extinction occurs.
After looking around the best I’ve come up with is that the MVP (minimum viable population) for many creatures is in the region of

<50-<500

To explain this, it means that a population of 50 is critical to prevent inbreeding problems, and a population of at least 500 is critical to prevent genetic loss through natural genetic drift.
So for a species to survive effectively it really needs 500 at least, even more so when you consider how much marine creatures wander.

However for the purpose of argument I'm happy to go with a conservative of 500. (Also consider not all of these are breeding, some are young, some old, some die before they get a chance)



Now that we have a number for how many megalodon's we need we next need to look at food, as it’s the primary thing for anything to survive. Since its closest living relative is the great white, then that’s all we have to base any real theories upon. It's generally accepted that sharks need to consume around 2% of their bodyweight per day to live. (Note this doesn’t mean it has to be that much every single day, just that amount on average)
So we take a look at the approximation of megalodon's size, ok i've looked at a number of sites and suggestions and generally it seems that it was around 40-50ft in length and around 30-40 tonnes in weight. Yes that’s 30,000 kilograms!!!!! One big fish.

Working with a general 2% rule this gives us a daily food requirement of 300 kilograms per individual. So then a simple case of multiplying that by the minimum needed 500 specimens gives us a nice little figure of 150,00kg per day consumed by this species at a bare low figure. (I’m using the smallest number of specimens and also going with a conservative figure for body mass)

Ok so in the vast depths of the oceans 150 tons a day may not sound like a great deal. However you then need to take some basic rules of nature into account.

All activity requires energy, and all things eaten provide energy. To survive you need to consume more energy than you actively use ( by actively I mean things such as walking, working and such. all stuff you do consciously) Without this you won't have the reserves to repair damaged tissues, grow or reproduce.
With this in mind it becomes obvious why all predators when hunting will choose the largest food source that will provide them with the needed energy. There’s no point in chasing a hundred mice (whilst easy to kill) if at the end of it you expelled more energy than they provide, better to kill one antelope.

So when you consider megalodon's size it's safe to rule out pretty much anything smaller than perhaps an elephant seal as a prey item, it just wouldn't be worth megalodons time and effort to try to catch smaller more agile prey. I'm happy to concede it did scavenge, but not as it's primary source. This was a hunter that may have scavenged, not a scavenger that may have hunted.

Ok then to conclude, we have a species that is consuming at least 150 tons of food a day that consists of large prey items. It's been suggested that megalodon typically preyed upon whales as food, and I can see it as a feasible idea when you consider its size. (even killer whales will take on other whales for food) As many thing in nature show with an animal design, if it aint broke don't fix it. So if still around today, it would likely still be feeding on whales as a primary food source.


Here lies the problem for me that amount of that kind of stuff being eaten would show up as a noticeable impact, even if you didn’t see this stuff happening there would be evidence of it. The whale that got away with battle scars, washed up corpses with injuries pertaining to their demise.


There’s just too many things that would make such a massive predator visible to us that hasn't ever been seen for me to think it can still be around.

Commendably organized research, feygan, but I'd like to play Devil's advocate if I may.

You're right that the population would have to be of considerable size in order to prevent genetic decay. However, an entire species of only fifty or so organisms might well exist in an unexplored benthic environment, even very large ones. Being so few in number, and assuming that they are not the only creatures to exist at these depths, the issue of food supply can be somewhat alleviated, assuming the species is spread out somewhat; this factor would also contribute to their scarcity.

One would think that we would have discovered evidence of the creatures by this point, but the fact remains that we have concrete proof that Megalodon existed, and that it is really impossible to say for sure that they really are extinct. Consider the Coelacanth, which was thought to have been extinct for some eighty million years due to their disappearance from the fossil record. In 1938, however, a fishing boat caught a live Coelacanth, and it was revealed that they had simply been inhabiting places less favorable to fossilization.

Adjusting for the greater depth at which these theoretical modern Megalodon live, and for the natural and elemental ravages that await the creature's remains upon death, it is entirely possible that the Megalodon has simply found itself in the same circumstances as the Coelacanth.

[edit on 9/15/2004 by Odd]

There are ample amounts of coelocanths to form a breeding population, we've documented that. Same goes for the squid, we captured babies of the giant squid. Not so for a large shark of that type. I won't deny that we may find a large hitherto unknown big-a$$ shark deep down under, but I doubt it would be the type of predator that megladon or a great white is. I'll bet if we would find something like the megamouth.

All very interesting. I would like to point out a few of things:

#1 in Feygan's dissertation on the consumption of an alleged Megaldon population, he stated that 2% of 30,000kg was 300kg. In fact it is 600kg making the numbers all that much higher.

#2 the Megamouth shark (Megachasma pelagios) was not known to exist until 1976. With an estimated maximum length of 17ft it does not fall into to the same group as a 40ft shark, but still quite a large animal to go unnoticed for so long.

#3 the whale shark (Rhincodon typus) is a massive beast that feeds on some of the smallest known oceanic organisms: plankton, anchovies and sardines, it just eats enormous quantities of them. Suppose that the Megalodon adapted a similar feeding pattern and just eats massive quantities of smaller fish rather than going after large prey animals for its primary sustenance. The Orca, while it does attack the occasional large prey animal) exists mostly on fish and seals - again in large quantities.

Just food for thought, so to speak.

Thanks for pointing out the blinding error in my maths. (got a little caught up in a ton of pages i forgot to proof check it.

However my argument against it adapting to feed on smaller prey is due to the solitary nature of such a creature. Since the great white is it's closest living relative then we have to use that as a basis.

Before anyone points it out, I realise that Great Whites have been encountered in small groups uses "pack" tactics. They still were aiming for large prey though, not small fish. Both the Great White and Megalodon just don't have the right equipment for small prey items, the huge teeth are designed for mortally wounding (if not killing) in one hit. It's something the animal does very well at, and so would have no reason to change.

True the Orca is an truely remarkable pack hunter, but when you look at the way it's social structure along with its basic body design is made up you can see how this comes to be. (small teeth indicates small prey as a primary source) It would be like a lion going after a field mouse, even if it caught enough to survive it just wouldnt have the right equipment to feed effectively.

I can see where the minimum 50 specimens could be applied but (although im no genetisist) I just feel that such a small number would have interbred themselves into extinction even before humans graced the planet.


Perfect examples of succesful designs that stick are crocodilians, they have had the same basic features for millions of years, and barring a meteor or other major event, will probably continue to do so. In the battle of predator vs prey a species only devolps new designs when it's current ones are being counteracted.

The only things that have caused this is the general shrinking of animals of the sea, thus meaning agiligy have become a bigger factor. This is one of the reasons why I just can't get into my head an acceptance for Megalodon to still exist. I think it's a case of Megelodon dying out for being just too big and clumsy and the Great White developing to takes it's place as the top dog of the shark world.
Sure it would be fasinating to see them around, but the figures all seem stacked too heavily against them, along with a lack of what should be fairly common evidence for such an animal. (remember it's actually 300 tonnes per day not 150, thats the equivalent to 10 humpbacks per day)

It was actually discovered, fairly recently, that the Megalodon is more akin to the Sand Tiger than the Great White. The teeth did not match closely to the G.W. and extrapolating the teeths shape to size and how they would fit into a jaw, it was wider and narrower than the G.W. Still a monster of a fish though!

[edit on 15-9-2004 by Der Kapitan]

Ok never knew that about the Sand Tiger reference, however it just adds weight to an argument against them being around still.
Sand Tigers (or grey nurse) are very very sociable, often seen in gruops of 2-3 dozen at a time. Take that and throw the size factor of Megalodon, and it would certainly leave plenty of evidence.

Hrm... I wasn't aware of the sand tiger thing. That may change things a bit.

Just for the record, though, I really have no opinion on whether or not the thing exists; I just thought I'd say what occured to me at first glance.

But you gotta admit... it would be pretty damn cool

If they are more closely related to the sand tiger and that is a schooling fish, that lies the possibilty of the megalodon also being a "pack" hunter. Hence they could survive on schools of fish as well as large prey items. Please bear in mind that the Great White doe NOT focus solely on large prey animals it (like the tiger shark) is a pretty indiscriminate eater. Combine this with the fact that large animals have been discovered in recently (see also Feygans post on the strange pachyderms) keaves room for the possibility that theses beasts are still out there.

Hey maybe the megalodons are eating all the ways and its not the Japanese hunting the to extiction! No, its probably the Japanese - but I tried.

I rmemebr reading an article about this megalodon about maybe 6 -8 months ago on here at ats, or on another news site, and it said some researcher found a megalodon tooth on a beach, 12 years ago. wasn't fossilised. laying ont he sandy beach....

True a pack like mentality could enable it to survive on fish. Also true that the Great White isn't soley a large prey item predator. The problem is when you look at the equipment of them. The fish types the Great White hits are all fairly large species, that are also very high in types of protiens and oils. It doen't just go after anything, chasing mackeral when your 20ft just doen't make good energy sense. Though they do take them when young.

Even if megalodon were to adopt a pack method of hunting fish, it would have had to evolve to maximise this. Without doing so would be like hunting rabbits with a .50 calibre rifile. Sure your gona be able to do it, but there won't be anything of value left afterwards.
Taking that into account, you'd be left with a creature that would have a nature more closely resembling the Orca than a Great White. It just wouldn't need to be as ferocious to hunt.

Maybe their primary food is giant squid. Now we have solved two problems: why we don't find any live giant squid and the megalodon's primary food source

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