Living Fossils Are Right at Home in the Deep Ocean.

The earliest life on Earth lived deep in the ocean. So, it’s fitting that some of the oldest “living fossils” would still reside there. A living fossil is an organism that has existed in its current form for millions of years, outsurviving any near-relative species. The depths of the ocean are teeming with examples of these prehistoric creatures. The alien-like chambered nautilus appears to live just as it did over 400 million years ago, descending as deep as 2,600 feet (800 meters) to ensnare fish and small crustaceans in its tentacles. Frilled sharks, a closer relative of the long-extinct megalodon than modern sharks, have wide jaws adorned with 20 – 30 rows of razor-sharp teeth.

Perhaps the most intriguing living fossil is the coelacanth. The large fish looks unremarkable at first glance, but it has fascinated scientists for decades for the insight it provides into evolution. The fish was believed to have been extinct millions of years ago until it was spotted in the 1930s. Researchers are still learning about the fish’s unique traits that have allowed the species to survive for over 360 million years. Coelacanths are massive, growing up to 6 and a half feet long and 200 pounds. They are the longest-living fish species on record, with lifespans of up to 84 years. The fish also grow extremely slowly, not reaching sexual maturity until their 40s or 50s. Coelacanths have four fins on the bottom of their body that move like land animals’ limbs and give birth to live offspring rather than eggs like other fish.

Even the Deepest Parts of the Sea Are Polluted

Unfortunately, there is no part of the planet that is safe from human pollution, not even the depths of the ocean. A 2017 study found chemicals that enter the water decades before are still present in deep-sea water. Even worse, the toxic chemicals had seeped into the tissue of some of the animals that make call the ocean home. And because these pollutants are biodegradable, they are likely to persist in the environment indefinitely, causing unknown harm to the ecosystem.

A 2018 expedition discovered trash and microplastics in the Mariana Trench, which contains the lowest point on Earth’s surface and has been protected by international law as a U.S. national monument since 2009. The extent of the pollution in the trench and other deep-sea locations is unknown, but any level of contamination could disrupt the marine life that has flourished there for eons. Without efforts to protect the deep sea, we could lose the oldest ecosystems on Earth.

Where Do We Find This Stuff? Here Are Our Sources:

Ten things you never knew about the ocean’s deepest places

Amazing Facts – Deep Sea Conservation Coalition

9 strange deep sea creatures you want to know

The deepest-dwelling fish in the sea is small, pink and delicate

16 creatures from the bottom of the ocean that will give you nightmares

The Deep Sea | Smithsonian Ocean