Buzz
This list explores fish that have existed since ancient, prehistoric times and have managed to survive up until today, still maintaining their ancient appearance. Feel free to point out any fish I may have missed in the comments below.
10. Hagfish
Hagfish have been around for more than 300 million years, predating even the dinosaurs! Living in deeper ocean waters, these creatures are often referred to as slime eels, though they are not true eels and may not even be classified as fish by some experts. Hagfish are incredibly unique; they possess a skull but no backbone, and surprisingly, they have two brains. These creatures are almost blind and feed on the carcasses of large marine animals like fish and cetaceans that sink to the ocean floor. Their nickname comes from their ability to secrete a slippery slime that suffocates predators by clogging their gills, making them almost invulnerable to natural enemies.
9. Lancetfish
The lancetfish presents a distinctly “prehistoric” look, characterized by its sharp, menacing teeth and a sail-like fin along its back, similar to the sails seen in some dinosaurs (though, in the case of the lancetfish, it’s actually an enlarged dorsal fin). Its scientific name, Alepisaurus ferox, also echoes that dinosaurian feel. Reaching up to two meters (6′ 6″), this fearsome predator can be found in all oceans except the polar regions. Extremely carnivorous, it feeds on smaller fish and squid, and occasionally even preys on others of its own kind.
8. Arowana
Part of the ancient Osteoglossid family, these fish have been around since the Jurassic period. Today, they can be found in the Amazon, as well as parts of Africa, Asia, and Australia. Occasionally kept as exotic pets, arowanas are aggressive hunters, preying on any small animal they can catch, including birds and bats, which they often snatch from midair (capable of leaping up to 2 meters or 6′ 6″). In China, they are known as “dragon-fish” because of their dragon-like appearance, and are considered symbols of good fortune.
7. Frilled Shark
This deep-sea predator, one of the most primitive sharks still alive, is a remnant from the Cretaceous period, when dinosaurs dominated the Earth. Rarely seen alive, and only recently filmed, the frilled shark can reach lengths of up to 2 meters (6′ 6″), with females being larger than males. Found in deep waters, they primarily feed on squid. These sharks are harmless to humans, and most spend their entire lives without ever encountering a human. Usually, only deceased or dying specimens are encountered by fishermen or scientists.
6. Sturgeon
A true survivor from the age of dinosaurs (having existed since the early Jurassic), the sturgeon is famous for being a primary source of caviar, made from its roe or egg masses. Unfortunately, due to overfishing, these magnificent, armored fish are now endangered. The largest species of sturgeon can reach lengths of up to 6 meters (19′ 7″), rivaling the size of a great white shark. They feed on small creatures found on the ocean floor and pose no threat to humans, unless provoked. However, their massive size has led to accidents where they unintentionally harm or even kill people by leaping out of the water and landing on boats.
5. Arapaima
A close relative of the arowana (see #8), the Amazonian arapaima is often considered the largest freshwater fish on Earth. Early reports suggest they could grow as long as 4.5 meters (14′ 8″), though today, such giant individuals are rarely found. Most adult arapaimas average 2 meters (6′ 6″) in length. These slow-moving predators hunt smaller fish, crustaceans, and any other small creatures they can swallow. Notably, the arapaima must breathe oxygen from the air to survive, similar to cetaceans. Although they are not dangerous to humans, they are often hunted for their meat, and unfortunately, their numbers are dwindling. The arapaima, though appearing in the Miocene period, belongs to the ancient Osteoglossidae family, which dates back to the age of dinosaurs.
4. Sawfish
This critically endangered species is a living remnant from the Cretaceous period. Found in both saltwater and freshwater environments, sawfish have been spotted as far as 100 kilometers inland. Growing up to 7 meters (23′) in length, sawfish resemble sharks but are more closely related to rays. Their iconic “saw” is not only a weapon, but also a sensory organ, covered in electro-sensitive pores that help them detect prey despite having poor eyesight. While usually peaceful, sawfish can become highly dangerous if threatened. A remarkable fossil discovery reveals that enormous, prehistoric sawfish were likely prey for the giant carnivorous dinosaur, Spinosaurus, as a vertebra from the fish was found lodged in its teeth.
3. Coelacanth
The Coelacanth is widely regarded as the most famous “living fossil,” earning its place as #1 on this list as the quintessential example of a “Lazarus taxon”—species once thought to be extinct but later rediscovered. Coelacanths were believed to have vanished with the dinosaurs during the Cretaceous period, until a live specimen was caught off the coast of South Africa in 1938. Since then, additional specimens have been spotted and photographed, and in 1999, a second species was discovered in Indonesia. These large predators, which can grow up to 2 meters (6′ 6″), feed on smaller fish, including small sharks, and prefer deep, dark waters. Though they rarely become a food source due to their unpalatable taste, coelacanths are now critically endangered.
2. Polypterus Senegalus
These African fish, often called “dinosaur eels” due to their reptilian look and serrated dorsal fin that resembles the spiked backs of certain dinosaurs, are not actually eels but members of the bichir family. Bichirs have existed since the Cretaceous period, making the “dinosaur” label rather fitting. Despite being popular as exotic pets, these “dinosaur eels” are notorious for escaping their tanks. They can survive out of water for extended periods, as long as their skin remains moist, allowing them to travel far from their aquatic homes.
1. Alligator Gar
This imposing, thick-scaled predator is native to the southern US and parts of northern and eastern Mexico, and holds the title of the largest freshwater fish in North America—though it occasionally ventures into the sea. Capable of growing up to 4 meters (13′) in length and weighing as much as 200 kg (440 lbs), the alligator gar gets its name from its reptilian look and elongated jaws, lined with two rows of sharp teeth. As aggressive ambush predators, they have been known to bite humans on rare occasions, although no confirmed fatalities have been reported. Gars are some of the most ancient fish still swimming today, with their lineage dating back to the Cretaceous period.
