Everything You've Wanted To Know About Ancient Fish And Their Lives

Joan Agie
Feb 29, 2024 By Joan Agie
Originally Published on Nov 15, 2021
Living fossil of an ancient fish is intriguing to animal lovers.
Age: 3-18
Read time: 8.5 Min

There are different species of fish that exist today.

Many of the ancient fishes have adapted while some of them have become extinct. While some species live in the deep sea, others like to live in the shallow waters.

Research scientists developing and searching fossil data on ancient marine life have found data indicating that the ancient species called coelacanth roamed the waters of Earth around 400 million years ago. Although the research is still being carried out, there is enough evidence suggesting the existence of coelacanth in ancient times.

Fish are fine aquatic vertebrates that swim along in shoals and search for food while saving themselves from larger fish and dangers from human capture. Most deep-sea fish are protected from human capture as humans are unable to reach those depths and even if they can, they prefer not to. Interestingly, some sea creatures like jellyfish, starfish, and crayfish are not considered in the group of fishes, they have different scientific names due to differences in their structures and functions. All fishes have scales, fins, and the ability to communicate with each other. Fishes have tiny brains but each species has lovely vibrant colors and looks. The acoustic sounds assist fishes to communicate within their own species.

After reading about the life of ancient fish species, also check how long can fish go without food and how long can a fish live out of water?

What is the most ancient fish?

Scientists have been actively involved in finding marine species that existed millions of years ago. Several fossils and other records provide evidence of the existence of ancient fish. According to the latest evidence found and the dating of marine fossils, it has been found that the most ancient fish was bigger and larger than the whale sharks that we know today. These ancient fish have come to be known as Leedsichthys Problematicus.

These enormous ancient fish were seen as great discoveries. They were seen to be extinct 165 million years ago and were last recorded to be seen in the waters of South Africa. They roamed in the deep waters of the islands near the south. These ancient fish have a bony structure. Scientists have discovered fossils of several extinct species of fish. Some of these fossils are very detailed while others only present minimal detail of some extinct creatures. The oldest fossil was recovered from South Africa and the nearby islands.

Live science research today has found  Metaspriggina Walcotti as the oldest fish to ever live in the Earth’s waters. It was just 2.36 in (6 cm) long and its fossils date back more than 400 million years. This was a fascinating ancient fish with eyes towards the outside and seven gills. Their presence and sudden disappearance are still a mystery. It did not have a bony skeleton which is probably why its fossil is not well preserved.

Is the coelacanth still alive?

The coelacanth was identified as an extinct ancient species of fish. Coelacanth was last seen 400 million years ago, which is approximately 150-170 million years before the disappearance of dinosaurs. However, in recent decades, coelacanth has resurfaced in an evolved form.

Initially, it was believed to have a lifespan of 20 years but it now seems that this fossil was not an accurate depiction of this species. The recently evolved version has several distinctive features. The coelacanth is now being referred to as a lobe-finned fish because of the look of its evolved fins. These fins seem a lot like limbs and might become the first land vertebrates over a period of time.

There are specifically two regions where the evolved species are found and they are named after these regions - African coelacanth and the Indonesian coelacanth. The African coelacanth lives near African islands, mostly towards the south. These are the only two species of coelacanth that are known and recorded in recent decades.

Due to their ancient lineage and evolved nature, these are extremely sensitive and need to be taken care of, however, they have evolved in the deep waters for so long that it seems better to let them remain in nature and not in human reserve centers. They are often referred to as the living fossils as the fossils of this species were found and studied and presumed dead until the evolved species came into light.

What fish were around with the dinosaurs?

Science states that coelacanth were giant fish species that existed around the time of dinosaurs. These ancient marine fishes lived in the deep sea and were the size of an average human. Ancient species of coelacanth are known to live for 100 years. Its breeding process starts very late, at around 59-60 years of age and pregnancy lasts for five years.

The earlier coelacanth was believed to live for 20 years, however, on using advanced techniques, scientists found that their lifespan extended up to 100 years on average. These fish were slow swimmers. A species that came around the late Jurassic period was the leedsichthys. It is considered to be the largest extinct ray-finned fish. Science shows that the species of fishes that we see today have ancestors who were present during the Jurassic period. This suggests that those species, although extinct in their ancient giant forms, have evolved and are now roaming in the deep sea as slightly different and adapted versions.

Ancestor Of The Great White Shark

As mentioned above, all the species of fish that exist today have their ancestors dating back to ancient times. Live Science has discovered more fishes apart from lobe-finned evolved coelacanth. There are fish species with evolved lungs as well. The results of live science today can find out the species that existed 66 million years ago and even those who swam in the deep sea around 400 years ago. Fossils have been discovered of these ancient fish species after a lot of research and digging into marine life.

Scientists for a long time thought that megalodon was the ancestor of the great white shark. This ancient fish was much larger than the enormous white shark that we see today. They were enormous enough to consume whales. However, in recent years, it was discovered that an even closer ancestor of the great white shark. Mako shark is a closer ancestor of great white sharks. Although mako sharks are not as enormous as megalodon, they were fast swimmers and ate other fishes around them. These are believed to exist more than 66 million years ago. The live great white sharks roam the oceans freely.

ancient fish were found as a fossil

Ancient Fish Lifespan

Ancient fishes like coelacanth had a lifespan of 100 years. However, 100 years is just the average lifespan. They may have lived even longer. According to the research in live science, ancient fish were found as a fossil and specimens around the coast of South Africa. The discovery of their specimen along the coast helps to portray the history of the ocean around the coast of South Africa.

The length of living fossils was much more than most species of fish found today. Such a discovery made using science, marked a milestone in marine research. Several bony animals have also been discovered. The bones found in most fish act as structural support and lead to the making of good fossils, however, not all fishes are bony or have bones and therefore, it is difficult to understand the fossils of these sea animals without bones. The Discovery of sea animals along the coast also demonstrates their natural habitat during that time and can assist in understanding the food preferences of the sea animal that has been discovered.

Ancient Fish Adaptations

The modern fish species that we see today were discovered to have evolved from the ancient enormous length fishes. The concept is very much similar to the discovery of apes having evolved into modern humans. The climatic conditions, the environmental and human factors have definitely changed a lot in the 400 million years.

Change is a part of life. It is a natural process and as our environment changes, so do we. The ancient fish became extinct and new species started to appear from the mutations that took place over the years. Ancient species did not just disappear. Over the years by a series of mutations, the original characteristics of the ancient fishes faded away and a new species seemed to have developed. The specimens that were discovered clearly show the history of ocean life. The length of the modern fish has also become more adaptive and they have become lighter. These light fishes are able to swim faster in the ocean.

The adapted fishes have differences in their bony structures and modern jaws. Lungfish are another great species of modern adaptations. Traditionally a prehistoric fish, this species is found swimming in the muddy waters of Africa.  Ancient fish had primitive lungs which allowed them to survive in estivation. Like all modern fishes, this fish also breathes through its gills, however, due to the adaptation from its ancestors, it is able to consume oxygen from the air as well. Ancient fish protected themselves by simply laying low, however, the adaptations over the years have enabled them to create protective habitats around themselves.

How did they die out?

Ancient fish did not breed often, they were sparsely populated and spread far across the oceans. These fishes were not great at hiding or protecting themselves. As the years passed by and environmental changes came along, it became difficult for the ancient, prehistoric species to survive in their natural forms. These ancient fishes also took a long time to mature which is probably why their population was so slim.

Over the years as human beings started to expand their livelihood and develop new ways of living, the ancient fishes started to lose their habitat. It was around the same time that modern vertebrates started to appear and take over the seas. Slowly small vertebrates with limbs also began to appear.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for ancient fish then why not take a look at how long do glofish live, or how long do fish live?

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Written by Joan Agie

Bachelor of Science specializing in Human Anatomy

Joan Agie picture

Joan AgieBachelor of Science specializing in Human Anatomy

With 3+ years of research and content writing experience across several niches, especially on education, technology, and business topics. Joan holds a Bachelor’s degree in Human Anatomy from the Federal University of Technology, Akure, Nigeria, and has worked as a researcher and writer for organizations across Nigeria, the US, the UK, and Germany. Joan enjoys meditation, watching movies, and learning new languages in her free time.

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