A new study suggests that prehistoric algae, marine plant life that lived alongside the dinosaurs, managed to survive the extinction event that killed the large reptiles - by learning how to eat other living beings.
The death of the dinosaurs, designated as the Cretaceous-Tertiary extinction event or the K-T event, is mostly believed to have been caused when an asteroid crashed into Earth some 65.5 million years ago. The impact caused large amounts of debris and soot to be blasted off into the atmosphere, creating a global climate and geological upset that soon led to the death of the dinosaurs. Scientists believed that this impact caused darkness and rapid cooling of the world's temperature, with some noting that the waters might have even been acidified, killing off its marine inhabitants - except a type of algae.
AVERY ISLAND, LA - AUGUST 21: Algae covers a pond in a wildlife refuge on Avery Island, home of the Tabasco hot sauce factory, on August 21, 2019, in Avery Island, Louisiana. Avery Island, a dome of salt surrounded by marshes near the southern Louisiana coast, is where the iconic Tabasco sauce has been made for the past 150 years. Like much of southern Louisiana, coastal marshland around Avery Island is disappearing at a rapid pace and the island is losing about 30 feet of surrounding protective marshland per year. As land gradually retreats from the area, the island becomes more susceptible to flooding from severe storms.
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Surviving Through and Evolving Diet
A team of scientists including those from the University of California - Riverside set on a study to understand how algae - among the most basic components of the food chain - survived an event where most life on Earth did not.
"This event came closest to wiping out all multicellular life on this planet, at least in the ocean," explained Andrew Ridgwell, co-author of the study and a geologist from UCR. He added that should algae be removed from an ecosystem's food chain, the rest of the chain should not survive.
"We wanted to know how Earth's oceans avoided that fate, and how our modern marine ecosystem re-evolved after such a catastrophe," Ridgwell added.
Researchers then examined fossils of the algae in question, creating 3D computer models and simulated possible scenarios that led to the changing feeding habits of the algae, publishing their findings in Science Advances.
Ridgwell explained that the very small fossils, almost several micrometers wide, were found in fast accumulating sediments with high clay contents, preserving the algae in generally good conditions. A layer of calcium carbonate further shielded the fossils used in the study, with holes suggesting that there were thin strands called flagella, allowing these microorganisms to swim.
Mixotrophic Microorganisms
The press release explains that algae species related to the prehistoric marine organism also have chloroplasts, the same organelles that allow for the synthesis of food from carbon dioxide and water using sunlight. It gives the algae the ability to survive either by feeding on other creatures or through photosynthesis - called mixotrophy.
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Researchers discovered that after the K-T event darkness, the mixotrophic algae moved from coastal shelf areas and into the open ocean, becoming a crucial and dominant life form for the next periods, serving as the foundation of the following food chains. The study also notes that the initial absence of larger creatures that feed on algae also helped them dominate the waters post-dinosaurs.
"The results illustrate both the extreme adaptability of ocean plankton and their capacity to rapidly evolve, yet also, for plants with a generation time of just a single day, that you are always only a year of darkness away from extinction," Ridgwell explained. However, after a couple of million years, algae evolved and lost the ability to feed on other creatures.
In time for Halloween, Ridgwell noted the algae adaptation as the ultimate story - "when the lights go out, everyone starts eating each other."
Check out more news and information on Algae in Science Times.
