A new fossil discovery is rewriting leech history. Scientists uncovered a 430-million-year-old specimen that proves leeches are far older than once believed. This finding suggests they hunted in oceans long before turning to blood.
The fossil was found in Wisconsin’s Waukesha biota. It shows a teardrop-shaped body with segments and a large tail sucker. Modern leeches also carry this feature.However, this ancient leech lacked the forward sucker that modern species use to pierce skin. This absence points to a very different lifestyle. Instead of draining blood, early leeches likely swallowed soft-bodied prey or drank their fluids.
As paleontologist Karma Nanglu explained, “Blood feeding takes a lot of specialized machinery.” Therefore, early leeches were simpler hunters.
Until now, experts thought leeches appeared only 150–200 million years ago. This fossil pushes their origin back by at least 200 million years. Preserving such a soft-bodied animal is extremely rare.
Leeches lack bones or shells, so fossilization requires unusual conditions. Researchers compared the discovery to “hitting the lottery twice.” Rapid burial and low-oxygen water helped protect the body.
This discovery highlights how much we still have to learn about life’s beginnings. Today, leeches live in fresh water, salt water, and even on land. Their diets range from scavenging to blood feeding.
However, this fossil proves their earliest ancestors thrived in oceans as hunters. As Nanglu noted, “The tree of life has deep roots, and we’re just beginning to map them.”
This ancient leech fossil is a reminder that evolution often surprises us.
Fossil Reveals Leeches Were Ocean Hunters Before Bloodsucking
