Apart from the fact that his puns are terrible and he has an obsession with the more surreal side of Internet culture, Oll Lewis hasn't put a foot wrong since we started this bloggo-thing. Because of his interest in things aquatic he has been co-ordinating the lake and sea monster news for the CFZ for some years now, and as regular readers of this bloggo will already know he is letting this obsession spill over online.. In my last blog, I wrote about the sightings of great white sharks in British coastal waters, but there was one species of shark far more fearsome than Jaws himself. That shark was megalodon (Carcharocles megalodon). Megalodon is perhaps the largest predatory fish to have ever lived, with the most reliable estimates of the shark’s length (estimated from the size of the shark’s teeth) standing at been between 17 to 18.2 meters (56 - 60 ft). This not only dwarfs the great white shark but is even longer than the largest extant fish, the whale shark; the largest known specimen of which measures 12.65 meters (41.5 ft). Megalodon’s jaws were so large that a man could easily have walked through them; it’s teeth measured up to 18 cm long.
Megalodon became extinct around 1.5 million years ago, a mere blink of an eye in terms of geological history, and many of the creatures it is known to have preyed upon, sperm and bowhead whales for example, are still extant. The sharks are thought to have become extinct as a result of climate change, when the sea level dropped at the start of the ice age. This cut the sharks off from the warm estuaries which had acted as breeding sites and nurseries for their young. As well as that, many of their prey species retreated to colder waters which were too cold for the megalodon. The megalodon was a highly specialised predator, so when most of the large mammals it preyed upon were no longer around, the species would have found it increasingly difficult to feed itself, which would have caused a large drop in numbers. This would have made it even more difficult for these, probably solitary, animals to find mates.
Some, however, contend that relict populations of megalodon could still exist in, or close to, the present day. As evidence for this witness reports of sharks much larger than any known species and/or exhibiting strange behaviour are often sited. Sadly these sightings are usually secondary accounts from un-named witnesses. The most often quoted eyewitness account of a supposed megalodon was recorded by John Stead in his book ‘Sharks and Rays of Australian Seas’ (1963):
“In the year 1918 I recorded the sensation that had been caused among the "outside" crayfish men at Port Stephens, when, for several days, they refused to go to sea to their regular fishing grounds in the vicinity of Broughton Island. The men had been at work on the fishing grounds — which lie in deep water — when an immense shark of almost unbelievable proportions put in an appearance, lifting pot after pot containing many crayfishes, and taking, as the men said, "pots, mooring lines and all". These crayfish pots, it should be mentioned, were about 3 feet 6 inches in diameter and frequently contained from two to three dozen good-sized crayfish each weighing several pounds.
“The men were all unanimous that this shark was something the like of which they had never dreamed of. In company with the local Fisheries Inspector I questioned many of the men very closely and they all agreed as to the gigantic stature of the beast. But the lengths they gave were, on the whole, absurd. I mention them, however, as an indication of the state of mind which this unusual giant had thrown them into. And bear in mind that these were men who were used to the sea and all sorts of weather, and all sorts of sharks as well. One of the crew said the shark was "three hundred feet long at least"! Others said it was as long as the wharf on which we stood — about 115 feet! They affirmed that the water "boiled" over a large space when the fish swam past. They were all familiar with whales, which they had often seen passing at sea, but this was a vast shark. They had seen its terrible head which was "at least as long as the roof on the wharf shed at Nelson Bay." Impossible, of course! But these were prosaic and rather stolid men, not given to "fish stories" nor even to talking about their catches. Further, they knew that the person they were talking to (myself) had heard all the fish stories years before! One of the things that impressed me was that they all agreed as to the ghostly whitish colour of the vast fish.”
I’m inclined to agree with Stead that if nothing else the size of the beast is most likely a wild exaggeration, but I’m not at all convinced that the ‘shark’, if indeed the fishermen were telling the truth, was a shark at all. Where they mention ‘water boiling’ over the animal this sounds more consistent with the crocodilia; several species of which produce low pitched growls while in shallower water. When growling like this the water looks as if it is boiling above the animals back. This is not something sharks have ever been recorded doing and it is highly unlikely that a species of shark would evolve that would be capable of this. Despite this sighting often being used to back up claims of megalodon surviving to the present, the only thing in the passage that even suggests the creature the fishermen saw was megalodon is the size of the animal. Stead himself does not suggest megalodon as a possible candidate for the identity of the animal.
Personally, I think that megalodon went extinct long ago, and there is little evidence to back up claims of possible surviving relict populations, but this is one of those occasions where I would be happy to be proved wrong.
Megalodon became extinct around 1.5 million years ago, a mere blink of an eye in terms of geological history, and many of the creatures it is known to have preyed upon, sperm and bowhead whales for example, are still extant. The sharks are thought to have become extinct as a result of climate change, when the sea level dropped at the start of the ice age. This cut the sharks off from the warm estuaries which had acted as breeding sites and nurseries for their young. As well as that, many of their prey species retreated to colder waters which were too cold for the megalodon. The megalodon was a highly specialised predator, so when most of the large mammals it preyed upon were no longer around, the species would have found it increasingly difficult to feed itself, which would have caused a large drop in numbers. This would have made it even more difficult for these, probably solitary, animals to find mates.
Some, however, contend that relict populations of megalodon could still exist in, or close to, the present day. As evidence for this witness reports of sharks much larger than any known species and/or exhibiting strange behaviour are often sited. Sadly these sightings are usually secondary accounts from un-named witnesses. The most often quoted eyewitness account of a supposed megalodon was recorded by John Stead in his book ‘Sharks and Rays of Australian Seas’ (1963):
“In the year 1918 I recorded the sensation that had been caused among the "outside" crayfish men at Port Stephens, when, for several days, they refused to go to sea to their regular fishing grounds in the vicinity of Broughton Island. The men had been at work on the fishing grounds — which lie in deep water — when an immense shark of almost unbelievable proportions put in an appearance, lifting pot after pot containing many crayfishes, and taking, as the men said, "pots, mooring lines and all". These crayfish pots, it should be mentioned, were about 3 feet 6 inches in diameter and frequently contained from two to three dozen good-sized crayfish each weighing several pounds.
“The men were all unanimous that this shark was something the like of which they had never dreamed of. In company with the local Fisheries Inspector I questioned many of the men very closely and they all agreed as to the gigantic stature of the beast. But the lengths they gave were, on the whole, absurd. I mention them, however, as an indication of the state of mind which this unusual giant had thrown them into. And bear in mind that these were men who were used to the sea and all sorts of weather, and all sorts of sharks as well. One of the crew said the shark was "three hundred feet long at least"! Others said it was as long as the wharf on which we stood — about 115 feet! They affirmed that the water "boiled" over a large space when the fish swam past. They were all familiar with whales, which they had often seen passing at sea, but this was a vast shark. They had seen its terrible head which was "at least as long as the roof on the wharf shed at Nelson Bay." Impossible, of course! But these were prosaic and rather stolid men, not given to "fish stories" nor even to talking about their catches. Further, they knew that the person they were talking to (myself) had heard all the fish stories years before! One of the things that impressed me was that they all agreed as to the ghostly whitish colour of the vast fish.”
I’m inclined to agree with Stead that if nothing else the size of the beast is most likely a wild exaggeration, but I’m not at all convinced that the ‘shark’, if indeed the fishermen were telling the truth, was a shark at all. Where they mention ‘water boiling’ over the animal this sounds more consistent with the crocodilia; several species of which produce low pitched growls while in shallower water. When growling like this the water looks as if it is boiling above the animals back. This is not something sharks have ever been recorded doing and it is highly unlikely that a species of shark would evolve that would be capable of this. Despite this sighting often being used to back up claims of megalodon surviving to the present, the only thing in the passage that even suggests the creature the fishermen saw was megalodon is the size of the animal. Stead himself does not suggest megalodon as a possible candidate for the identity of the animal.
Personally, I think that megalodon went extinct long ago, and there is little evidence to back up claims of possible surviving relict populations, but this is one of those occasions where I would be happy to be proved wrong.
Posts
No comments:
Post a Comment