Welcome back to the Abstract!
In the immortal words of a wise crab: “Darling it’s better down where it’s wetter, take it from me.” That’s why we’re going to be under the sea for most of this week’s column, though the wonderful things that surround us will be 1) massive flesh-eating sharks 2) conveyor belts of whale excrement and 3) alien microbes.
Depending on your proclivities, then, you might be alternately relieved or bummed to leave the ocean depths and return to land for one last story about atmospheric oxygen, which is a very handy element for those who don’t enjoy asphyxiation (no judgement!). Where did Earth’s oxygen come from? Scientists make the case for ancient volcano burps. Let ‘em rip.
Jaws vs. the Meg: This Time, It’s Peer-Reviewed
It’s time to check in with the heavyweight champ of sharks: Megalodon. Yes, star of the acclaimed films The Meg, Mega Shark vs. Mecha Shark, Shark Attack 3: Megalodon, and Bigfoot vs. Megalodon: The Legends Are Real.
Megalodon, which went extinct two million years ago, was a big-ass shark. Indeed, it may have been the biggest-ass shark that ever swam the seas. And now scientists have proposed that this animal was even bigger than previously assumed, measuring an astonishing 24.3 meters (80 feet!) in length and weighing in at 94 tons (188,000 pounds!).
“Otodus megalodon is represented primarily by its gigantic teeth measuring up to at least 16 cm and possibly as much as about 20 cm in height,” said researchers led by Kenshu Shimada of DePaul University. “However, the lack of complete fossil specimens has resulted in uncertainty regarding the true size of this prehistoric shark. This paucity of fossil material has hampered our understanding of the biology and ecology of O. megalodon, despite its presumed significant role in shaping the modern-day marine ecosystem as one of the largest carnivores that ever existed.”
Many previous studies have speculated that Megalodon had a similar body plan to its relative, the 15-foot-long great white shark (Carcharodon carcharias), which would put the extinct predator around 60 feet in length. Shimada and his colleagues instead suggest that Megalodon “likely had a slenderer body” than great whites, which would stretch its expanse out another 20 feet.
First of all, I hope these findings inspire a new franchise called Slendershark that combines Slenderman creepypasta with the Megalodon action/horror subgenre. You’re welcome, Hollywood. Secondly, the team also validated the existing film Jaws vs. The Meg with this little nugget:
“Additional inferred growth patterns corroborated by the known fossil record support the hypothesis that the emergence of [great white sharks] during the Early Pliocene is at least partly responsible for the demise of O. megalodon due to competition for resources,” the researchers said.
So as it turns out, the winner of Jaws vs. The Meg is the iconic apex predator that still roams the seas today. Coronate the GwsOAT (Greatest white sharks Of All Time).
The Great and (Gross) Whale Conveyor Belt
We move now from the great white shark to the great brown shart. I’m talking poop from whales, people. Also on the list: pee, placenta, and dead meat produced by migrating baleen whales like grays, humpbacks, and North Atlantic and southern right whales. All of this delightful corporeal junk contributes to what is known as the “great whale conveyer belt,” a trail of nutritious remnants that whales leave behind as they migrate from high-latitude feeding ground to their winter breeding grounds in the tropics.
Scientists have attempted to quantify the impact of this cetacean excrement flow on surrounding ecosystems and the results are impressive. Migrating whales “convey an estimated 3,784 tons of nitrogen per year” (mostly from their pee) and “46,512 tons of biomass per year” (mostly from their carcasses) “to winter grounds,” said researchers led by Joe Roman of the University of Vermont.
“These numbers might have been three times higher before commercial whaling,” the team said. “To our knowledge, baleen whales provide the largest long-distance nutrient subsidy on the planet.”
Indeed, the enrichment provided by even one individual female whale is astonishing. “On each calving journey, she would leave 77 kilograms of nitrogen and 774 kilograms throughout her life,” the study reports. “At the end of her life, her 27-ton body would transport 2,782 kg of carbon to the ocean floor” creating a huge “nutrient pulse.”
Many marine ecosystems depend on this vibrant cocktail of urea, feces, afterbirth, and dead bodies. But while the study outlines cool concepts like the “whale pump” (the vertical movement of nutrients), it also offers a dire warning about the projected decline of the great pee tunnel as baleen whales increasingly struggle with a variety of human-driven pressures.
“Although many [whale] populations have increased since the demise of commercial whaling, future recovery is imperiled by human actions such as shipping, fishing, and climate change,” Roman and his colleagues said. “Populations of humpback and right whales in the Southern Hemisphere, for example, will likely peak around 2050 and decline along with changes in ocean temperature, sea ice, and primary productivity. Such changes could disrupt one of the world’s most prominent links between high- and low-latitude marine ecosystems.”
If we humans dare to disrupt the great whale conveyor belt, we deserve to have some of it hosed into our faces.
My Cup of (Alien Moon Water) Runneth Over
We move now from the seas of Earth to the seas of Enceladus, a weird little walnut of a moon that orbits Saturn. Though it is only 300 miles wide, Enceladus is a promising place to look for life because it squirts plumes of its subsurface ocean into space from icy surface geysers, making it theoretically easy for a life-hunting spacecraft to scoop up samples without even having to land. Indeed, the Cassini spacecraft (RIP) already sampled the plumes, but it was not equipped with life-detection instruments.
Now, scientists have produced new models that reveal what might be going on under Enceladus’ ice crust. With the help of Cassini data, the new study models how alien seawater travels from hydrothermal vents around the moon’s rocky core all the way up to the plumes erupting from its surface, particularly at the South Pole, where ice is thinnest.
“Geophysical and chemical analysis data from the Cassini spacecraft revealed that Enceladus harbours a global salty ocean with continuing hydrothermal activity underneath an ice crust of very uneven thickness: 20–25 km on average, more than 30 km in some equatorial regions and less than 5 km beneath the South Pole,” said researchers led by Mathieu Bouffard of Nantes Université.
“Here we perform three-dimensional numerical simulations of the ocean dynamics,” the team said. “Our simulations confirm that a strong heterogeneous seafloor heat flux concentrates upwellings at the South Pole, thus efficiently transporting organic matter from hydrothermal vents to erupting plumes.”
“Chemical observations by future missions to Enceladus may…allow the identification of the best spot for collecting materials from the deepest and freshest parts of the ocean,” the study concluded.
In other words, any life that exists around Enceladus’s hydrothermal vents can get a one-way ticket into space if it’s in the right place at the right time. This moon is potentially an alien sprinkler just waiting for a mission to come sample its watery innards. While concept missions to Enceladus have been proposed, nothing has been formally greenlit, which sort of boggles the mind. What are we waiting for? Let’s go chug some moon juice already!
The Breath of Life Is a Hot Magma Belch
Are you ready to emerge from seas filled with massive carnivorous sharks, whale sewage, and putative alien lifeforms? Would you like to breathe the fresh air on land again? We now surface for a story about the atmospheric oxygen that has led to the proliferation of life on Earth.
About 2.5 billion years ago, oxygen levels in the ocean-atmosphere system skyrocketed to levels we are familiar with today. This transition, known as the Great Oxygenation Event, was driven by the emergence of photosynthetic bacteria that exhaled oxygen into the world and paved the way for an age of exploding biodiversity.
But before this event, during a period called the late Archean, the oxygen levels were much lower, supplied only by transient oxygenation events called “whiffs” (the actual scientific term). Now, scientists think they have a lead on the origin of at least some of these whiffs: Swaths of land covered in volcanoes known as Large Igneous Provinces (LIPs) that frequently erupted for about 500 million years leading up to the Great Oxygenation Event.
“Our biogeochemical model indicates that a whiff of oxygen—a transient oxygenation event of the atmosphere during the late Archean—could have been triggered by intense volcanism,” said researchers led by Yasuto Watanabe of the Japan Meteorological Agency.
“The whiffs during the late Archean infer that the Earth system was approaching a tipping point for the permanent oxidation of the atmosphere,” the team said. “Our results highlight the mechanistic link between planetary volcanic activities and the dynamic evolution of the atmosphere at the dawn of the Great Oxidation Event.”
In short, the fresh air we breathe today may have originally flowed from the magmatic rumblings of our ancient planet. Your weekend mantra: Inhale. Exhale. Erupt. Whiff. Namaste.
Thanks for reading! See you next week.
