Leedsichthys problematicus, an extinct pachycormid fish, is believed to be the largest fish ever lived, growing up to 22m in length. It was a planktivore and lived during the Late Jurassic period. Its fossils have been found in England and Germany.
The largest fish that ever lived is Leedsichthys problematicus. It is thought to have grown to a length of 22 m (72 ft), about the length of a school bus, although this estimate cannot be certain because a complete spine has not been found. Regardless, it’s fairly certain that Leedsichthys is the largest ever-living fish that scientists are currently aware of. That’s more than twice the size of the whale shark, the largest fish in today’s seas. The closest living relative of Leedsichthys is the triggerfish.
Leedsichthys problematicus was discovered by fossil collector Alfred Leeds and the species was named in his honour. Leedsichthys means “fish of Leed”, while problematicus is a reference both to the difficulty of imagining a fish of this size, and to the difficulty of classifying it once found. Leedsichthys was a pachycormid, an extinct group of bony fish. Shortly after it was discovered, it was realized that it was the largest fish that ever lived.
Fossils of the fish found in England and Germany have been dated to 155 million years ago, during the Late Jurassic period when dinosaurs roamed the Earth. Like the whale shark and numerous whales, Leedsichthys was a planktivore, meaning it exclusively consumed plankton. It would have been prey to marine carnivores of the time, such as the plesiosaur Liopleurodon.
One of the largest Leedsichthys fossils was found in Peterborough, England, where it was discovered as a tangled mass of fractured bones. Unlike large dinosaurs, Leedsichthys had delicate bones, many of which were crushed by the weight of clay over millions of years. One of the largest specimens, called the Big Meg, has filled over 20 museum drawers with its bones. Its queue alone included over 10,000 fragments.
Investigations of Leedsichthys fossils have shown that 8 – 10% of its body mass was compromised by organic material it consumed, such as algae and plankton.
Pachycormids like Leedsichthys were eventually replaced by a new group called teleosts, which comprise 95% of all fish alive today. Teleosts have produced a greater number of eggs, concentrating less care on each individual, and this evolutionary strategy has proved successful. However, no teleost can claim the title of largest fish ever.
Protect your devices with Threat Protection by NordVPN
