What Are Zombie Worms And Why Is Their Absence Worrying Scientists?

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Last Updated:December 31, 2025, 13:25 IST

These deep-sea creatures survive by feeding on the bones of dead whales, but their significance runs deeper. Disappearance of zombie worms may signal a hidden crisis in the oceans

Deep in the dark, silent depths of the ocean, some of the strangest creatures on Earth thrive on death. Known as zombie worms, these deep-sea organisms survive by feeding on the bones of dead whales. When researchers from Ocean Networks Canada (ONC) and the University of Victoria placed humpback whale bones nearly 1,000 metres below the surface, they expected the bone-eating Osedax worms to appear swiftly, just as they usually do in the deep-sea environment.

Using high-resolution underwater cameras, scientists monitored the whale bones for nearly ten years. Surprisingly, not a single zombie worm was detected during this period.

A Warning Sign For Ocean Health

The absence of Osedax is being seen as a serious warning about the health of ocean biodiversity and the marine food cycle.

It suggests that oxygen-minimum zones, areas of the ocean where oxygen levels are dangerously low, are expanding, making it increasingly difficult for marine life to survive.

Why Do Zombie Worms Matter?

Zombie or osedax worms are a unique species found in the deep sea. They feed on the bones of dead whales, playing a crucial role in recycling nutrients within marine ecosystems. This unusual feeding habit is why they are often referred to as ‘zombie worms’.

Osedax worms are about one centimetre long and have no mouth or digestive system. Instead, they use root-like structures to burrow into bones. Symbiotic bacteria living within these roots help extract nutrients from the bone tissue, allowing the worms to survive.

These worms rely heavily on whale carcasses, known as whale falls, for survival. In the past, Osedax species have been found in both the Pacific and Atlantic Oceans, making their complete absence in this study particularly concerning.

Low Oxygen Threatens Worms And Microbes

As stated above, scientists believe the main reason for the disappearance of zombie worms is the expansion of oxygen-minimum zones, a process closely linked to rising ocean temperatures. Barkley Canyon, located on the southwestern coastline of Vancouver Island, British Columbia, where the experiment took place, is naturally low in oxygen and lies along major whale migration routes.

The lack of oxygen affects not only the worms themselves but also the symbiotic microbes they depend on. As oxygen levels drop, both species struggle to survive, placing these specialised ecosystems at risk.

Expert Warning On A Growing Global Crisis

Professor Emeritus Craig Smith from the University of Hawaii, who co-led the experiment, warned that the expansion of oxygen-minimum zones due to ocean warming spells trouble for whale-fall and wood-fall ecosystems along the north-eastern Pacific margin.

Scientists view these findings as a ‘negative outcome’, showing that even naturally low-oxygen environments can become unsuitable for key species. This trend is part of a broader pattern of global marine deoxygenation, which threatens marine life and undermines the United Nations Sustainable Development Goal 14, focused on protecting life below water.

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