‘Snowball Earth’ was crushing and cold. What animals could survive it?
Planet Earth was once something like a combination of a deep freeze, and a car crusher. For large stretches of Earth’s history, everything was squashed under a blanket of ice that was a kilometer thick. This is what scientists call snowball Earth.
Some early animals were able to survive this cold era, which lasted roughly 720 to 580 millions years ago. However, they had a lot of work ahead of them. Despite their valiant achievements, the repeated expansions and contractions of giant ice shelves pulverized the remains of the hardy extremophiles leaving little to no trace in the fossil record. Scientists have no clue how they survived.
Huw Griffiths, British Antarctic Survey, says that it’s “basically like having a huge bulldozer.” “The next glacial expansion would have erased all that and made it into mush, basically.”
Griffiths believes it is reasonable to suggest that snowball Earth was home to a wide range of animal life, despite the lack of direct evidence from all that glacial-churning. He suggests that this flourishing would predate the so-called Cambrian blast, which occurred around 540 million years ago and saw an unprecedented amount of animal life on Earth. Griffiths states that it is not difficult to imagine that simpler, smaller things existed before that.
Griffiths and his colleagues have a complete picture of animal life in this period, but it is not possible to know everything.Take a look at a recent paperTry to figure it outmightWhat it looked like.
The team looked at three types of frozen periods. The first was the Sturtian Snowball Earth, which occurred around 720 million years ago. It lasted up to 60 millions years. This is an incrediblely long time. It’s almost as long as the time between the end of dinosaur era and the present. Then came Marinoan snowball earth, which began 650 million years ago but lasted only 15 million years. It was followed by the Gaskiers glaciation, which occurred around 580 million year ago. This third glaciation was even shorter and is often called a “slushball” rather than a “snowball Earth” because it had less ice.
Scientists have discovered a few remnants of fossils from these periods that were lost to the ice. These fossils are a rare representation of strange animals that lived around the Gaskiers glaciation. Among these ancient slushball-Earth dwellers were the frondomorphs–organisms that looked a bit like fern leaves. Frondomorphs were found beneath the seafloor and may have absorbed nutrients from the water.
Griffiths and his coworkers argue that the survival strategies of animals during great freezes are likely to be echoed today by life in Antarctica, which is the most similar environment on Earth.
Some of the modern Antarctic inhabitants includeAnemonesLiving upside down, affixed on the underside sea ice, is a great way to stay hydrated. Krill enjoys grazing microorganisms on the upturned plane as a favorite feeding strategy. Griffiths and his colleagues believe that early animals may have foraged and sought shelter in such places, as Griffiths and his coworkers suggest.
It is possible that algae or other microorganisms from sea ice were introduced into seawater by the waxing and waving of sea ice, allowing them to grow and provide food for other early animals.
The possible lack of oxygen was one of the problems that snowball Earth’s inhabitants faced. This was due to low oxygen levels and limited mixing of water from the atmosphere. However, animals that depended upon oxygenated meltwater high up in the water column may have been able to survive on oxygenated meltwater. There are some Antarctic seafloor dwellers today, including certain species offeather starThis problem can be solved by relying upon water currents to bring a steady stream of oxygen and nutrients from the small open areas at the surface to the deep below the ice shelves. This is also possible during the Gaskiers slushball earth period.
Griffiths says, “We are really speaking about very basic forms life… but at that time that’s all one would have needed to be the king of the beasts.”
The seafloor may have been home to sponges along with frondomorphs. Griffiths says that some fossil evidence of sponges can be found well before the Sturtian snowball earth, but there is some controversy over this.
Ashleigh Hood, a sedimentologist from the University of Melbourne in Australia, jokes that “everyone has their oldest sponge that’s been found in the record and nobody else believes them”.
Some modern sponges liveSymbiotically with bacteriaThey may be able to access nutrients when food is scarce. Hood suggests that Hood believes this is likely a survival strategy they used early in their history.
Andrew Stewart, an assistant curator at Museum of New Zealand Te Papa Tongarewa, was not involved in the paper. He has studied many species from harsh Antarctic environments. Many of these organisms can survive in extremely dark, cold, or toxic environments. Stewart believes that Antarctic extremophiles are a reminder about how resilient life on Earth is, and has been, for many years.
He said, “It’s just a most amazing place.” “You go, Bollocks, it’s impossible for anything to survive there!” It can, in fact.
Frederick has been an active trader for over since 1991. After successfully navigating the market for so long, he’s finally bringing his wisdom to the masses.