KOMPAS.com – According to the new analysis, the vampire squid has languished in the darkness of the oceans for 30 million years.
Modern vampire squid (hell Vampyroteuthis) can breed in ocean waters that lack oxygen. This behavior differs from many other squid species which require shallow habitat along the continental shelf.
Some of the fossils of vampire squid ancestors are still alive, so scientists are not sure when this elusive cephalopod developed the ability to live on less oxygen.
Analysis of the new fossils helps fill a 120 million-year gap in the evolution of vampire squid, revealing that the ancestors of modern-day vampire squid lived in the deep oceans during the Oligocene, 23 million to 34 million years ago.
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“These squids probably evolved, adapting to low-oxygen water during the Jurassic period,” said study co-author Martin Koš? Ák, a paleontologist at Charles University in Prague.
“Life with stable low oxygen levels brings evolutionary advantages – lower predation pressures and less competition,” Koš? Ák said as quoted by Antara. Live Science, Monday (22/2/2021).
Koš? Ák and his colleagues discovered long-lost vampire squid fossils in the collections of the Hungarian Museum of Natural History in 2019 while searching for fossils of cuttlefish ancestors.
The fossil was originally discovered in 1942 by Hungarian paleontologist Miklós Kretzoi, who identified it as a squid about 30 million years old and named it Necroteuthis hungarica.
However, further researchers argue that it is the ancestor of cuttlefish.
In 1956, during the Hungarian Revolution, the museum was set on fire, and its fossils are expected to be destroyed.
The rediscovery was a happy surprise.
Koš? Ák and his colleagues studied the fossil by scanning electron microscopy and carrying out geochemical analysis.
Koš? Ák’s findings indicate that Kretzoi’s initial identification was correct. The fossil comes from a squid, not a cuttlefish ancestor.
The animal’s inner shell, or gladius, which forms the backbone of its body, is about 6 inches (15 centimeters) long.
While the length of the squid, including the arms, is about 13.7 inches (35 centimeters).
This size is only slightly larger than the modern vampire squid, which reaches a total length of about 11 inches (28 centimeters).
The sediments surrounding the fossils show no trace of the microfossils often found on the ocean floor. This shows that the ancient squid did not live in shallow water.
The researchers also analyzed the level of variation in carbon in the sediments and found that the sediments likely came from anoxic or low oxygen environment.
This condition is a characteristic of the deep sea floor.
By looking at the rock layers above where the fossils were stored outside of Budapest, the researchers were also able to show that the squid might not have been able to survive in the shallower seas at that time.
Shallow marine deposits exhibit extremely high levels of certain plankton blooming in a low-salt, highly nutritious environment, conditions that modern vampire squid cannot tolerate.
Researchers from the Monterey Bay Research Institute (MBRI) found that while hiding in the deep sea, this squid did not behave like the nightmare predator its name implies.
Instead, they wait in their dark habitat for crumbs of organic matter to fly. Then, they caught the pieces with a sucker covered in mucus, MBARI found.
Adapt to depth
The new research, published Thursday (18/02/2021) in the journal Communications Biology, hints at how the ancestors of vampire squid learned to live where no other squid could live there.
Looking deeper into the fossil record, the oldest fossils of this group of squid were found in the Jurassic period, between 201 million and 174 million years ago and they are usually found in anoxic sediments.
“The main difference is that this oxygen deficiency occurs in a shallow water environment,” he said.
“This means that the ancestors were inhabitants of shallow water environments, but they adapted to low oxygen conditions.”
There are gaps in the fossil record in the Lower Cretaceous, starting about 145 million years ago.
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The squids may have shifted to deeper seas by this time, said Koš? Ák, because of their experience with anoxic conditions in the Jurassic.
This deep-water lifestyle may explain why the squid survived the crisis that killed the nonavian dinosaurs at the end of the Cretaceous period, he added.
“The squid that lived in from 30 million years ago helps connect recent history with a deep past,” Koš? Ák said.
He and his colleagues are now trying to make a similar connection for squids, a cute, color-changing group of squid that have similarly murky origins.
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