The seemingly alien "vampire" is actually a "living fossil" on Earth that existed much earlier than the dinosaurs

Lampreys are one of the oldest vertebrates on Earth, with a history of more than 300 million years. Lampreys are vertebrates that appeared earlier than dinosaurs. They spend their infancy in the mud of rivers, undergo metamorphosis like tadpoles turning into frogs, and spend their adulthood in the sea or lakes.

It has a large round mouth that looks like a suction cup, and the densely packed sharp keratin teeth in its mouth are daunting. Its predatory behavior is also very terrifying - it attaches its suction cup tightly to other fish and sucks blood until the prey is tortured to the point of being weak and even dead. The title of "underwater vampire" comes from this, and it has also become the artistic prototype of underwater murderous monsters in horror science fiction movies.

In appearance, the lamprey resembles an eel, with a slender body, bare skin and no scales, a small dorsal fin, a high front caudal fin that extends backwards and wraps around the end of the body, a single nostril between the two eyes on the top of the head, and 7 gill openings on each side of the body behind the eyes, which is why it is called a "lamprey".

Modern lampreys are one of the few vertebrates that undergo metamorphosis in their individual development history. They have a three-stage life cycle, just like tadpoles turning into frogs. After metamorphosis, they develop from larvae to adults with very different morphology and ecological habits, which also includes fundamental changes in feeding methods. Some larvae do not have suction cups and their mouths are funnel-shaped. They hide in the sand at the bottom of the water, sticking their mouths out of the sand layer, and the water flow will wash some debris and small organisms into their mouths. After a few years, the larvae undergo a metamorphosis process and enter adulthood, leaving the sand layer and starting a new life.

Modern lampreys have a variety of feeding methods. The blood-sucking species (such as the sea lamprey) are the most well-known, while there are fewer carnivorous species. There are also scavengers and species that do not feed after metamorphosis. Different feeding methods correspond to different tooth characteristics.

Lampreys have no bones and their teeth are made of keratin, making them difficult to preserve as fossils. The lamprey fossils in the Yanliao Biota are not only well preserved, but most importantly, their suction cups and teeth are preserved in an almost three-dimensional state, providing rare and precious samples for revealing the evolution of lamprey feeding behavior.

Based on previous understanding of the lineage relationships of modern lampreys and the characteristics of lamprey teeth, it is generally believed that the ancestor of modern lampreys was a blood-sucking type similar to the sea lamprey. However, the research and analysis of the Yanliao eel and the reconstruction of the ancestral state show that the ancestor of modern lampreys is more likely to be a type of carnivorous lamprey, and the characteristics of its teeth are closer to today's sac lamprey.

Lampreys are rich in nutritional value and have long been recognized as a tonic by the people. King Henry I of England was famous for his greed for lampreys. Charles Dickens wrote in "A History of England for Children" that during his inspection in Normandy, the 67-year-old Henry I, despite the doctor's advice, ate too much lampreys and eventually died of indigestion and fever.

References:

[1] Wu Feixiang. The transformation history of the “foodie” lamprey[J]. Science in Art.

[2] Qiu Shi. Biological characteristics and scientific research value of lamprey[J]. Trends and reviews.

[3] Hu Minqi. Revealing the past and present of the “blood-sucking monster” lamprey[J]. Popular Science.