Scientific studies tell us that as a species, human beings have been around for some time now. But we’re not nearly the oldest living species still around today. Although it can be hard to tell exactly how old some species are and scientists are confident that they still haven’t uncovered nearly all the fossils that could be found, most scientists agree that the oldest living species still around today is the horseshoe crab.
According to scientific research, the horseshoe crab that still exists today has been around mostly unchanged since the Ordovician period. When was that? How about 445 million years ago?
If that doesn’t sound incredible to you, think of it this way. The oldest multicellular animals found in fossils date back about 600 million years. Most species of animals usually only last a few million years. For example, the dinosaur Tyrannosaurus rex only existed for about three million years. Our species, Homo sapiens, has been around a mere 250,000 years!
The horseshoe crab, on the other hand, has been around for about 450 million years. That’s about three-fourths of the entire time that animals have existed on Earth. That’s incredible! Scientists believe its simple but effective immune system may be responsible for its longevity.
Even older fossils of familiar creatures have been found. For example, scientists have found extremely old fossils of the nautilus (500 million years old), jellyfish (550 million years old), and sponges (760 million years old).
These simple creatures existed even before the horseshoe crab, and they still exist today. However, their modern forms have evolved and aren’t the exact species of the ancient fossilized forms that scientists have found. Nevertheless, the nautilus, jellyfish, and sponge can claim to have ancient roots…and scientists believe there are probably even older fossils that haven’t yet been discovered!
The oldest plant species that still exists today is believed to be the Gingko tree, also known as Gingko Biloba. Gingko tree fossils have been found that date back 270 million years to the Permian period. Scientists believe its longevity is the result of insect-resistant wood and its ability to form roots and sprouts in the air.
The horseshoe crab, nautilus, jellyfish, and sponge may be some of the oldest living animal species and the Gingko tree may be the oldest living plant species, but they’re far from the oldest things found in the fossil record. Certain groups of bacteria have been around for billions of years. For example, cyanobacteria, blue-green algae that still exist today, have been around for over three billion years!