Arctic sponges discovered feeding on fossilized remains of extinct animals

Beneath the Arctic ice, on the slopes of dead volcanoes, scientists have found something that shouldn't exist: vast gardens of sea sponges thriving in one of Earth's most inhospitable places. The discovery, reported in Nature Communications by an international research team, reveals a feeding strategy so unusual that it rewrites what we thought possible in the deep ocean.

The sponges live atop the Langseth Ridge, an underwater mountain range near the North Pole. This is a place where sunlight never reaches, where the water is near freezing, and where the normal pathways of food—the rain of organic matter from the surface ocean—deliver less than one percent of what these animals need to survive. Yet here they are, in dense, thriving colonies. Antje Boetius, chief scientist of the expedition from the Max Planck Institute for Marine Microbiology, led the team in collecting samples and mapping the distribution of these sponge gardens across the seafloor. The question was immediate and pressing: what were they eating?

The answer came through chemical analysis of the sponges themselves. The animals were consuming fossilized worm tubes and the hardened remains of other creatures that had died thousands of years ago—the detritus of extinct life, turned to stone and locked in the seafloor. It was a form of feeding no one had documented before in the high Arctic. Teresa Morganti, the study's lead author and a sponge expert at the same institute, explained that the sponges possessed microbial symbionts capable of breaking down this ancient organic matter. The bacteria living inside the sponges were doing the heavy lifting, digesting and dissolving material so hard and chemically resistant that the sponges alone could never access it.

This symbiotic relationship is the engine of the ecosystem. Sponges, despite their plant-like appearance, are animals—simple ones, among the most basic forms of animal life. But they are not simple in their partnerships. The bacteria that colonize their tissues receive shelter and a stable home. In return, they produce antibiotics that protect the sponge's health. More crucially, they break down fossil material into forms the sponge can absorb and use for energy and growth. It is a transaction as old as life itself, refined here into a mechanism for survival in the abyss.

What makes this ecosystem remarkable is not just its existence but its isolation. The sponge gardens are rich in species—soft corals and other organisms cluster around them—yet they operate almost entirely on recycled death. The primary productivity of the water column above them, the photosynthetic energy that drives most ocean food webs, contributes less than one percent of the carbon these sponges require. They have, in effect, abandoned the sun-powered world and learned to feed on geological time itself.

Boetius called it unique, a word chosen carefully. Nothing like it had been seen before in the central high Arctic. Yet the team also noted something sobering: this garden may be transient. The fossils it feeds on are finite. The ecosystem is rich now, but it exists in a state of slow consumption, drawing down a resource that cannot be replenished. How long it will persist, and what will happen when the fossil reserves are exhausted, remains unknown. For now, it stands as a reminder that life finds ways to persist in places we thought impossible, using strategies we are only beginning to understand.