Zombie worms are missing and scientists are alarmed
When researchers lowered whale bones into the deep ocean, they expected zombie worms to quickly move in. Instead, after 10 years, none appeared — an unsettling result tied to low-oxygen waters in the region. These worms play a key role in breaking down whale remains and supporting deep-sea life. Their absence hints that climate-driven oxygen loss could unravel entire whale-fall ecosystems.
In horror films, the most frightening threats are often the ones you cannot see. In the deep ocean, scientists are now facing a similar kind of unease, driven by the unexplained absence of a crucial species.
That species is the zombie worm, formally known as "the bone devourer" Osedax. Its disappearance may signal deeper trouble ahead, including species loss and weakening ecosystems linked to long-term climate change.
A Decade-Long Deep-Sea Experiment
Fabio De Leo, a senior staff scientist with Ocean Networks Canada (ONC) and an adjunct assistant professor in the University of Victoria's (UVic) Department of Biology, co-led a long-term experiment off the coast of British Columbia (BC). The study placed humpback whale bones on the deep ocean floor and monitored them for signs of life.
After years of observation, researchers found no trace of zombie worms, despite their well-known role in breaking down whale bones and supporting deep-sea food webs.
How Zombie Worms Feed Without a Digestive System
Osedax worms are unusual creatures. They lack a mouth, anus, and digestive tract, yet they survive by drilling root-like structures into bone. Inside those roots live microbes that extract nutrients, which then nourish the worms.
Because of this unique role, Osedax is considered an ecosystem engineer, helping recycle nutrients and create conditions that allow other species to move in.
Why the Absence Is So Concerning
Over 10 years of high-resolution underwater camera footage from ONC failed to capture any zombie worm colonization. In scientific terms, this kind of outcome is known as a negative result, and it can be just as meaningful as a positive finding.
"This was a remarkable observation in such a long-term experiment," De Leo says. He adds that the absence may be linked to unusually low oxygen levels at the study site.
Low Oxygen Zones and Whale Falls
The whale bones were placed in Barkley Canyon, nearly a thousand meters below the Pacific Ocean surface. This area lies within a naturally low-oxygen zone and along migration routes used by humpback and grey whales.
When whales die from natural causes or human-related threats such as ship strikes or fishing net entanglements, their bodies sink to the seafloor. These events create "whale falls," which normally provide a sudden surge of food that supports rich biodiversity. The lack of zombie worms at Barkley Canyon suggests that expanding oxygen minimum zones (OMZs) in the northeast Pacific and beyond may be disrupting these ecosystems.
Early data from ongoing whale fall research near another ONC NEPTUNE site points to similar concerns elsewhere.
Why Bone Devourers Matter