Have you ever seen a shark attack

Megalodon : Could the basking sharks have survived in the deep sea?

The Australian marine biologists hadn't expected this: in 2003, they installed a tracking device and data logger on a great white shark. They called the healthy, female three-meter animal “Alpha” and wanted to find out where their kind hangs around on the Australian west coast. In addition to the location, the device also registered the water depth and ambient temperature.

When the biologists found the faded device on a beach four months later and read out the data, they were confused: On December 24th around 4 a.m., Alpha had swum a very long distance very quickly. Like a car chase. Then, within seconds, she had thrown herself down a continental slope to about 580 meters. The temperature rose from seven to almost 25 degrees. With the same heat, the transmitter then moved for six days between zero and 100 meters depth until it finally surfaced and was then washed up.

For the researchers, there was only one explanation: the huntress had become the hunted and fell victim to a larger robber who later eliminated the station. At most, 25 degrees prevail at this depth in the body of an animal, and the gastric juices would have made the transmitter bleach. But: which monster should eat a shark of this size? In terms of natural enemies, there are really only killer whales. But they don't dive that deep. And in the stomach of such mammals it is also warmer than 25 degrees. Big sharks are known to prey on smaller ones every now and then. But so big?

The question was not unreasonable: Are there still predatory fish of unimagined dimensions in the depths? Could even the megalodon survive - a basking shark up to 20 meters long that is said to have died out over 1.5 million years ago? He has already reappeared in the Hollywood film called "Meg - Bite Soon", which has been in cinemas for a week. But could it really still exist?

"In these unbelievably dark rooms there are certainly still many things and living beings to discover that we have no idea of," says Antje Boetius, marine biologist at the University of Bremen. In addition, it would not be the first time in recent times that a large species of fish has been discovered that was previously unknown or that was considered to have long been extinct.

The example of the coelacanth is well known. For a long time, researchers only knew of this bone fish, which can be up to two meters long, fossils that are over 65 million years old. That is why they thought that he had blessed the temporal with the mass extinction towards the end of the Cretaceous period. But in 1938 a specimen appeared in the net of a fishing trawler on the coast of South Africa. As a result, others were found, some of which even belonged to a different species.

The second big sensation is the discovery of the basking mouth shark in 1976. At that time, biologists pulled a 4.5 meter long male of this hitherto completely unknown species on board a research ship off Hawaii. It had dogged itself in a towline. To date, a good 60 other specimens have been spotted and clearly identified worldwide. The largest was over 5.50 meters long. There are probably even bigger ones.

Basking mouth sharks are not predatory fish, however. Like the up to ten meter long whale sharks, they sift through the sea with their mouths open for microorganisms, primarily krill. So what about large predatory fish - sharks that could be dangerous to a three-meter colossus like Alpha?

There is only evidence of megalodons from prehistoric times: fossils of teeth up to 17 centimeters long and a few vertebrae. There are no bones because sharks are cartilaginous fish. Except for those vertebrae, their skeleton has nothing to offer ossified, and cartilage only rarely fossilizes. Whale bones with basking shark bite marks have also been found. All of this is dated 1.6 million years or older. That is why most experts assume that it died out at that time.

However, some cryptozoologists who mostly deal with animals as a hobby, for whose existence there is only vague evidence, speculate that Megalodon has only moved: Because the competition from great white sharks, for example, has become too strong, he simply went to deeper realms and came rarely near the surface. The speculations are fed by sporadic eyewitness reports, such as one from 1918 by lobster hunters in Port Stephens, Australia: for several days they refused to go out to their fishing grounds near Broughton Island because there was a giant shark - 30 or even 90 meters long - there Raise mischief and plunder the lobster cages.

In 1959, the zoologist Vladimir Tschernezky from Queen Mary College in London contacted the science magazine “Nature”. He had analyzed two megalodon teeth that had been found in 1875 during a voyage on the research vessel HMS Challenger. They were coated with a thick layer of manganese dioxide. And the thickness of these deposits, according to Tschernetsky, can provide information about the age of the teeth because it increases by 0.15 to 1.4 millimeters per millennium. He calculated an age of 11,000 to 24,000 years. According to this, Megalodon would have been alive at least at that time. It would then be almost probable that it still exists today.

However, it is the most recent serious sign of life, and the date is also controversial. Manganese dioxide deposits, for example, are dependent on too many factors to provide reliable age information, with more specific evidence for other deep-sea monster sharks. The goblin shark, for example, looks bizarre. It can be over six meters long, has a pink body with blue-gray fins and a misshapen snout: flattened like a paddle, it extends far beyond the mouth. It contains electrical sensors, so-called Lorenzini ampoules, with which the shark can perceive the finest electrical signals, for example those that are produced by muscles at work. This is how the shark tracks down its prey - even if it is hiding in the seabed. In order to grab them, he can put his mouth full of pointed teeth forward, similar to the monster in the horror film "Alien".

Little is known about how the goblin shark lives. The isolated finds indicate that it occurs worldwide on the slopes of the continental plates and deep-sea mountains. Many other creatures cavort there too, so that it can easily prey on it. "We find several new species of shark in these habitats every year," says David Ebert, marine biologist at Moss Landing Marine Laboratories in California. "Around 50 alone are waiting in our laboratory for us to examine them and find a name for them." 535 real shark species are known, and many more would be added. “Most of the new species are no larger than one and a half meters.” Because precisely because of this, and because they often hide in crevices on the continental slopes, they have not been caught in a network for a long time and have not been noticed by any submarine camera.

Larger, also hardly explored species can be found on the mountain slopes of cooler sea areas - sometimes up to 2500 meters deep. Greenland sharks, for example. Described for the first time more than 200 years ago, a five-meter-long specimen was found in 2016 that is said to have been almost 400 years old - this would make Greenland Sharks the most long-lived vertebrates according to current knowledge. They could even get significantly older - and longer -. In 1995, a diving robot filmed a specimen at a depth of 2200 meters that measured over six meters. Experts believe that greenland sharks can go up to eight meters. And they can also make great prey: seals, large fish and polar bears were found in their stomachs - and once a human leg.

The closely related Pacific sleeping shark, which also lives in arctic waters, is similar in size. And the snub-nosed six-gill shark, which is at home in warmer regions and of which there are film recordings of how it tears a whale carcass that has sunk to the bottom to pieces.

So there are indeed large sharks that hunt along the deep-sea slopes - species that grow significantly longer than the great white shark alpha. At night they sometimes commute to the surface. But: Well-known deep-sea sharks are less powerful than the great white shark - and probably also more sluggish. That's why no expert trusts them to have killed Alpha.

That wouldn't be a problem for Megalodon - if he was still alive. But no serious scientist is expecting that. “We cannot rule out his survival one hundred percent,” says Ebert. But there are no signs of it. "All traces that we have found of Megalodon and that can be reliably dated are over 1.5 million years old."

Rainer Froese from the Geomar Helmholtz Center for Ocean Research in Kiel has another argument: “In the last 20 to 30 years - after the giant mouth shark was discovered a good 40 years ago - fishing has increased massively, especially on the continental slopes and seamounts . Sharks are often caught - including large ones like the Greenland Shark. "Megalodon was not among them. "That is why we can assume that there are no longer any great unknowns."

But then who killed Alpha? Australian marine biologist and documentary filmmaker David Riggs researched the case for his film "The Search for the Ocean's Super Predator". Result: Most likely, Alpha was eaten by an even more powerful great white shark. The animals do not spurn any conspecifics when they are hungry.

That, too, is speculation, and the Alpha murder case - like other deep-sea mysteries - remains unsolved.

Now new: We give you 4 weeks of Tagesspiegel Plus! To home page