MEGALODON
To me this is one of the most interesting aspects of the Great White shark. The Great White's prehistoric great granddaddy, is a giant prehistoric shark of the genus Carcharodon Megalodon. This ancient shark probably lived between about 16 to 1.6 million years ago. As far is known, it was the largest predatory fish to have ever lived. But recent studies have stated the shark may have gone extinct only 10,000 years ago. And who knows, maybe there is still one out there............maybe. It seems to me inconceivable that man can easily build ships able to go into space yet we still have not been to all of the deepest abysses of our own oceans.
Some relatively recent reports of large shark-like creatures have been interpreted as surviving megalodons, but such reports are usually considered misidentification of basking sharks, whale sharks or other large creatures. One well-known example was reported by writer Zane Grey. It is possible, but unlikely, that some of these sightings might be due to abnormally large great white sharks. One famed example was retold by Australian naturalist David Stead.
The best-educated estimates of this creature's maximum size range from 12 to 16 m (40 to 52 ft) (previous much larger reconstructions of the shark's size, up to about 30 m (100 ft), are now generally considered inaccurate but not completely out of the question).
The best-educated estimates of this creature's maximum size range from 12 to 16 m (40 to 52 ft) (previous much larger reconstructions of the shark's size, up to about 30 m (100 ft), are now generally considered inaccurate but not completely out of the question).
From the size of this shark, its weight is estimated as high as 60 tons, though 20 to 30 tons was more likely. Assuming similar metabolic-weight ratios as the great white shark, it is estimated that a large megalodon would need to eat about one-fiftieth of its weight of food on average per day. From our knowledge of the food chain during megalodon's existence, it is generally believed that this shark's diet consisted mostly of whales, along with large fish and primitive pinnipeds and sirenians (sea cows or lions).
The Kraken 
A man giving relative size comparison to Carcharodon Megalodon in museum. Imagine a small train...with teeth.
There is a theory that the adult Carcharodon megalodon fed largely on whales and went extinct as the polar seas became too cold for sharks, allowing whales to swim out of reach of sharks during summer. Other explanations are simpler, suggesting that any prolonged disturbance of the foodchain would wipe out a predator with such massive metabolic requirements. Some cryptozoologists suggest the shark might have died out more recently, or might even still be alive.
The fossil teeth of the animal are often found in areas that had shallow seas, such as near Bakersfield in California. Megalodon was probably a specialist that fed mostly on baleen whales in shallow waters. A main prey item was Cetotherium (a type of shallow water prehistoric whale). Since the time of its extinction there have been few such shallows supporting constant, large whale populations, and the loss of such habitats caused the animal to gradually go extinct, as the species could no longer find enough food to sustain itself. The process would have been gradual, leading to fewer megalodons, more genetic drift and isolated megalodon populations.
THE LARGEST SHARK JAW IN THE WORLD
Containing 182 fossil teeth, including four of the largest teeth ever discovered. Each of the four largest teeth measures over 7 inches, with the largest tooth measuring 7 5/8 inches. It is believed that in life, this shark would have measured over 75 feet in length. The jaw is a reconstruction, modeled after it's closest living relative the great white shark. Measuring 9 1/2 feet high x 11 feet wide, containing four rows of teeth.
The sillouette to the right shows you the relative size of this prehistoric monster. Modern day Great White, Man, Megalodon. Scary huh.
The other great sea monster of Norse myth and legend is the Kraken, said to be able to overturn ships and drag them down into the cold depths. There seems to be a degree of confusion with the Midgard Serpent, because some legends say there are only two Kraken in existence, and that these were born in the first creation and are destined to die only when the world itself finally perishes. This seems to be what Alfred Lord Tennyson (1809-1892) had in mind in his poem The_Kraken.
However, there are less apocalyptic tales about the Kraken - in particular about the 'young Kraken' - that contradict this, suggesting something on a lesser scale than the Midgard Serpent, though still scary enough. In the mid, I8th century Erik Ludvigsen Pontoppidan (1698-1764), Bishop of Bergen, tackled the long and hazy tradition of the Kraken in his Natural History of Norway (1752-1753). After scrupulously interviewing mariners he came up with this remarkable tale, which repeated a tradition that can be traced back to the 12th century but is certainly much older.
Fishermen told Erik Pontoppidan that sometimes when they rowed several miles out to sea, particularly on hot, calm summer days, they found that in areas where they were used to sounding a depth of 80-100 fathoms (50-60m), they would find it registering less than half this. If the fish were also jumping, the fisherman guessed that the Kraken was lurking below, stirring them up. So, while keeping a careful watch on their depth, lines, the men would gratefully catch fish until the monster showed signs of rising to the surface. Then they would haul in their nets and paddle for their lives.
Once clear they would rest on their oars and, as Pontoppiaan tells it, they would soon see an enormous monster rise to the surface - a creature so vast that no one could see the whole of it at once. The bishop says that it had the appearance of a number of small islands surrounded by something resembling seaweed: 'At last several bright points or horns appear, which grow thicker and thicker the higher they rise above the surface of the water, and sometimes they stand as high and large as the masts of middle, sized vessels. It seems these are the creature's arms and, it is said, if they were to lay hold of the largest man,of1war, they would pull it down to the bottom. After this monster has been on the surface of the water a short time, it begins slowly to sink again, and then the danger is as great as before, because the motion of this sinking causes such a swell in the sea, and such an eddy or whirlpool, that it draws down everything with it.' This curiously symbiotic relationship with the Kraken is explained by Pontoppidan: 'The Kraken have never been known to do any great harm, except that they have taken away the lives of those who consequently could not bring the tidings.'
Presumably he meant there were legends of ships and sailors being attacked, but that this was rare and never occurred in the circumstances he describes above. He personally heard only one close anecdote: two unwary fishermen suddenly ran into a 'young Kraken', one of whose 'horns' or tentacles 'crushed the head of the boat, so that it was with great difficulty they saved their lives on the wreck, though the weather was as calm as possible'. Writing as he was in the Age of Enlightenment, Pontoppidan was laughed to scorn by many naturalists who thought he had fallen for a bunch of fishermen's yarns. About the only part of his report seriously was his mention of the 'young Kraken'. This creature was well known to Norwegian fishermen; to judge by their descriptions, 'young Kraken' are quite clearly ordinary squid. But, although evidence was then emerging that squid could grow much larger than previously imagined, the suggestion that one might have a circumference of over a mile remained outrageous. Some rationalists suggested - as in other cases of supposed monsters surfacing at sea - that what the fishermen were talking about, in a garbled and fanciful way, was simply the surfacing of weed tangles, buoyed up by the gases of their own decomposition. But most people simply laughed the tales away.
Proof of a kind that Pontoppidan's sailors may not have been exaggerating came in a curious way during the Second World War. While hunting for German submarines off the coast of Norway, ships of the US Navy found a strange conundrum. Sometimes in areas where they knew the depth to be over 150 fathoms (90m) their sonar would indicate a much lower figure. Closer investigation showed that this phantom layer would rise gently towards the surface at night, then sink during the day. This suggested some kind of dense blanket of living organisms maintaining temperature by adjusting their depth.
The phenomenon is still unresolved but a reasonable suggestion is that it was probably caused by large schools of squid fanning out all at the same depth. And, if such a shoal surfaced, it might well appear, as Pontoppidan wrote, 'like a number of small islands, surrounded with something that floats and fluctuates like seaweeds'. So is the Kraken in the end no more than a large school of squid breaking the surface? Well, possibly, squid are continuing to surprise us by the size they can reach. One wonders, too, about the phantom submarines which both sides chased occasionally in Scandinavian waters during the Cold War. Perhaps squid may indeed reach a size still not fully appreciated by either science or the world in general, and thus be the true Kraken.
