Discover the 10 Oldest Species on Earth: The Ancient Species That Still Thrive Today

According to SAEDNEWS, Much of our understanding of Earth’s history comes from the fossil record, allowing scientists to reconstruct the evolutionary tree and the planet's geological development. Every species alive today can trace its lineage back to ancestors whose fossils are over hundreds of millions of years old. Many of these species are classified as "living fossils," meaning they have changed little from their original forms.

Equisetum (Horsetails)

Equisetum, commonly known as horsetails, is the sole surviving member of the plant class Equisetopsida, dating back more than 300 million years. These ancient plants once dominated late Paleozoic forests and grew as tall as 30 meters (98.4 feet). Today, horsetails are smaller and reproduce not through seeds but via spores, much like their ancient predecessors. While they are often considered weeds in various parts of the world, horsetails have been utilized by different cultures for food, medicine, and as a wood polish.

Coelacanth

Thought to have gone extinct around 65 million years ago alongside the dinosaurs, the coelacanth was rediscovered in 1938. This intriguing fish offers scientists a glimpse into the evolutionary leap from aquatic to terrestrial life. Its four fins resemble legs and move in an alternating pattern, similar to how a horse trots. Unique features, such as a joint in its skull that allows it to consume larger prey and thick scales absent in other fish, set the coelacanth apart.

Elephant Shark

Don’t be fooled by the name— the elephant shark is not a shark at all, but a type of cartilaginous fish known as a ratfish. It diverged from sharks approximately 400 million years ago, making it one of the oldest known vertebrate species. Researchers have sequenced the elephant shark’s genome, revealing significant differences from other vertebrates, which may help shed light on the evolution of bony skeletons. Its slow evolutionary rate means it has changed little over the eons.

Horseshoe Crab

The horseshoe crab is perhaps the most iconic living fossil, closely resembling its ancient ancestors found in fossils over 445 million years old. With their unusual appearance, these creatures are essential for testing vaccine safety due to the unique properties of their blood. Unfortunately, human activity poses a threat to their population, as around 500,000 horseshoe crabs are harvested each year.

Nautilus

With its distinct spiral-chambered shell, the nautilus has existed for roughly 500 million years. This remarkable cephalopod has not strayed far from its ancestors and is known to be the longest-living among cephalopods, boasting a lifespan of 15 to 20 years. Although not endangered yet, nautiluses are protected due to the threat of over-harvesting for their shells and use in aquariums.

Velvet Worms

Velvet worms, or Onychophora, are unique, wormlike creatures closely related to arthropods. Known for their soft, velvety skin and numerous stubby limbs, they are fascinating remnants of an ancient lineage that may have transitioned onto land between 490 and 430 million years ago. Their soft bodies don’t fossilize well, making the exact timeline of their land adaptation somewhat unclear.

Jellyfish

Jellyfish are believed to be among the oldest multi-organ animals, existing for over 500 million years. Fossils dated back to this time show that these enigmatic creatures may have been more complex than previously thought, challenging the notion that they lack a central nervous system.

Sponges

Sponges are widely considered the first branch from the common ancestor of all animals. Their fossils date back to about 580 million years, though some recent discoveries suggest they could be even older. Lacking true tissues and organs, sponges are unique in the animal kingdom, with thousands of species living in various marine and freshwater environments.

Ctenophores (Comb Jellies)

Previously thought to be the oldest animals, ctenophores, or comb jellies, have recently been reclassified as the first true animals based on genetic studies. This ancient group continues to intrigue scientists, especially since many genes related to human diseases are found within their DNA.

Cyanobacteria

Cyanobacteria are considered the oldest surviving life forms, possibly dating back 3.5 billion years. Fossilized stromatolites, layered rocks formed by microbial mats, provide some of the earliest evidence of their existence. This resilient bacteria species can be found in diverse habitats across the globe, exhibiting striking blue-green colors, particularly in aquatic environments.

These remarkable living fossils remind us of the deep history of life on our planet and the intricate web of evolution that binds all living species. Understanding these ancient organisms not only enriches our knowledge of biological diversity but also highlights the importance of conservation to protect these living pieces of our planet's history.