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.