Earth has been evolving since the time it was formed billions of years ago until it became habitable for plants, animals, and humans. But every change also means every living creature has to adapt and survive or else they end up dead. Surprisingly, there are animals that survived despite the mass extinctions and now hold the record as the oldest living species on Earth.
The "living fossils" are believed to have been around even when dinosaurs were still alive and were able to survive terrible mass extinctions that killed the majority of living things. But which animal has survived the longest?
Oldest Living Species on Earth
In November 2010, the tadpole shrimp (Triops cancriformis) was awarded the title of "oldest living creature" by the Guinness World Records. Fossils show that these armored, shrimp-like crustaceans have been around since the Triassic period between 251.9 million to 201.3 million years ago.
They are classified as endangered species in the United Kingdom since scientists have only found two colonies that were alive in July 2010 in the Caerlaverock nature reserve on the English coastline.
According to Live Science, tadpole shrimps have bodies that look like spades perfect for digging at the bottom of temporary pools where they live. Moreover, the design seems to have worked in their favor as it kept them alive for hundreds of millions of years.
Genetic research suggests that they still look the same as they have always been on the outside, but also revealed that they never stopped evolving underneath their armor. Due to this, it created different species across time that humans cannot spot.
A 2013 study published in the journal PeerJ showed that the tadpole shrimp T. cancriformis is just a descendent of a Triassic ancestor that looks like them and is no more than 25 million years old.
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Other Contenders for Oldest Living Species Title
There are other living fossils today that compete against the tadpole shrimp for the title of the oldest living species, Live Science reported. The most famous of them all is the deep-sea fish called coelacanths, which were discovered in the 1800s and were thought to be extinct 66 million years ago during the Cretaceous period.
Then in 1938, some fishermen hauled up a living coelacanth off the South African coast. They date back 400 million years ago but today's coelacanth is not the same species as the fossilized coelacanth species that went extinct. A 2010 study suggested that the living species emerged in the past 20 to 30 million years.
Similarly, the ancient horseshoe crab lineage that dates back to 480 million years showed that the oldest living group of Asian horseshoe crabs (Tachypleus) only emerged 25 million years ago despite looking similar to fossils from hundreds of millions of years ago, according to a 2012 study published in the journal Molecular Phylogenetics and Evolution.
But there could be older than the tadpole shrimp as biologists are not yet finished deciphering the evolutionary histories of all living animals. Three species tell science that even the most seemingly stable species are also always changing.
RELATED ARTICLE : Coelacanths: Four-Legged "Living Fossil" Fish Found in Madagascar
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