A carnivorous sponge nicknamed the ‘death ball’ was found 12,000 feet down near Antarctica

Scientists working through the latest Ocean Census project have added a carnivorous sponge nicknamed the “death ball” to a growing catalog of never-before-seen marine life. The animal was found roughly 12,000 feet down in the waters near Antarctica, one of dozens of new deep-sea species pulled from a stretch of ocean that remains almost entirely unmapped. Its discovery adds to a sustained push by marine biologists to systematically survey deep ocean basins that historically drew few research expeditions, largely because they sit far from established shipping lanes and research stations.

A sponge that hunts instead of filtering

Most sponges are filter feeders, pulling in seawater and straining out microscopic food particles without ever moving or actively pursuing prey. The “death ball” sponge belongs to a much smaller, stranger group of carnivorous sponges that abandoned filter-feeding altogether in favor of trapping and digesting small animals directly, a lifestyle that has only evolved in a handful of deep-sea lineages worldwide.

Carnivorous sponges tend to show up in nutrient-poor deep-sea environments, where filtering the water for scarce particles offers a poor return compared with actively snaring the small crustaceans and other invertebrates that drift past.

Biologists studying the broader carnivorous-sponge family have noted that the shift away from filter-feeding likely occurred independently more than once across different lineages, rather than tracing back to a single common ancestor that abandoned filtering. That pattern of repeated, independent evolution toward the same unusual feeding strategy is itself of interest to researchers who study how extreme environments can push otherwise unrelated organisms toward similar solutions.

How microscopic hooks do the work

Rather than a mouth or stomach, the sponge relies on tiny hook-shaped structures on its surface that function much like Velcro, snagging small crustaceans that brush against it. Once an animal is caught, surrounding tissue gradually envelops and digests it externally, a slow process suited to an animal that has no muscles, nerves, or means of chasing prey.

That hook-and-envelop strategy stands in sharp contrast to how most predatory animals capture and process food, since the sponge lacks any of the sensory or muscular systems typically associated with hunting. Instead, the entire process unfolds passively: prey must make physical contact with the sponge’s surface, at which point the hook-shaped structures do the trapping and the surrounding tissue does the rest, often over a span of days rather than the seconds or minutes most active predators require.

Life nearly two miles beneath the surface

At roughly 12,000 feet, the sponge lives in complete darkness under crushing water pressure and near-freezing temperatures, conditions typical of the deep seafloor surrounding Antarctica. Depths like this remain among the least-explored environments on the planet, reachable only with specialized submersibles and remotely operated vehicles built to withstand the pressure and cold.

The Southern Ocean in particular has been undersampled relative to other ocean basins, both because of its remoteness and because expeditions there require ships equipped to operate near sea ice, which has historically limited how much of the seafloor scientists have been able to survey directly.

Even reaching that depth is a logistical undertaking on its own, requiring specialized pressure-rated vehicles, dedicated ship time, and favorable ice conditions that can narrow the usable research season to only a few months each year. Those constraints help explain why so much of the Southern Ocean seafloor remains undocumented even as exploration technology has steadily improved in other parts of the world’s oceans.

One find among more than a thousand new species

The “death ball” sponge was one of roughly thirty previously unknown deep-sea species identified from the same stretch of the Southern Ocean, and part of a much larger tally: Ocean Census researchers documented more than 1,100 new marine species across a single year of fieldwork, working alongside partners including the Nekton Foundation. That total marked a sharp jump over the roughly 728 new species recorded the year before, reflecting both an expanded survey effort and how much of the ocean remains formally undescribed.

Coverage of the findings noted that the pace of discovery says as much about how little of the deep ocean has been systematically surveyed as it does about any recent change in the ocean itself — most of these species were almost certainly already there, simply unobserved until now.

Identifying a specimen as a genuinely new species typically involves comparing its physical structure against known relatives, and increasingly cross-checking genetic material against existing databases to rule out the possibility that an apparently novel organism is simply an unusual variant of something already described. That verification process is part of why large tallies of new species, like the more than 1,100 documented in this latest count, tend to be announced well after the specimens themselves were originally collected in the field.

A race to document life before it disappears

Researchers involved in the project have framed the discoveries against a narrowing window for finding them: deep-sea mining exploration, pollution, and warming waters are all expanding into parts of the ocean that were until recently too remote to draw much industrial interest. That raises the possibility that some newly cataloged species, including ones only just described, could face habitat pressure before scientists have had time to study them in any depth.

Researchers have pointed to seafloor mining prospecting in particular as a pressure point, since many of the mineral deposits of commercial interest sit at depths that overlap with where newly described deep-sea species, including carnivorous sponges, tend to be found. That overlap has fed calls from parts of the marine science community for baseline biological surveys to be completed before large-scale industrial activity expands into deep-sea environments that have barely been cataloged.

Why cataloging deep-sea sponges matters beyond taxonomy

Sponges are also of interest beyond basic classification because many produce unusual chemical compounds as a defense mechanism, some of which have drawn interest from researchers studying new antibiotic or anti-cancer compounds. A newly described carnivorous species adds another data point to that broader chemical library, even before any specific compound from this particular sponge has been studied in detail.

That chemical potential is part of why marine biologists have pushed to preserve tissue and genetic samples from newly described species rather than relying solely on physical specimens, since compounds of pharmaceutical interest can sometimes be identified years after a species was first cataloged. A carnivorous lifestyle in particular has drawn added scientific curiosity, since animals that trap and digest prey externally often rely on specialized enzymes to do so, compounds that carry their own separate research value beyond the novelty of the feeding strategy itself.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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