A mighty sponge lurks in the deep

Scientists exploring the depths around the Northwestern Hawaiian Islands have discovered the world’s largest sponge, a creature the size of a minivan.

“I was just astonished by the size of it,” said University of Hawaii-Manoa biologist Christopher Kelley, who discovered the animal with a colleague last year.

The scientific journal Marine Biodiversity published a study this week describing the enormous sponge that lives at a depth of 7,000 feet within the Papahanaumokuakea Marine National Monument.

Measured at 12 feet long, 7 feet wide and 5 feet tall, the massive sponge was documented during an expedition aboard the NOAA ship Okeanos Explorer to explore deep-water habitats of the Northwestern Hawaiian Islands using remotely operated vehicles at depths ranging between 2,300 and 16,000 feet.

On Aug. 12, Kelley and Papahaunau-mokuakea research specialist Daniel Wagner were operating a remotely operated vehicle surveying for deep-water corals and sponges on a seamount south of Pearl and Hermes Atoll.

The scientists were focusing the vehicle’s high-definition video camera on a coral when the remote vehicle turned and caught a glimpse of the huge specimen.

“It appeared out of nowhere and completely bowled us over,” Kelley recalled. “It was astonishing.”

The sponge colony was identified as belonging to the hexactinellid family Rossellidae and subfamily Lanuginellinae and is almost certainly a newly discovered species, Kelley said.

“It could be thousands of years old,” said Kelley, the program biologist for UH’s Hawaii Undersea Research Laboratory.

Not much is known about the life span of sponges, he said, although some large species found in shallow waters have been estimated to live more than 2,300 years.

Several marine sponges are known to reach massive sizes, according to the paper. They provide important ecosystem serv-ices, such as filtering large amounts of seawater and serving as key habitat to a variety of invertebrate and microbial species.

The previous record holder for size was a different type of sponge measured at 11 feet long, 3.5 feet wide and 1.6 feet tall, and discovered off Western Canada in 1887.

Kelley said that during a submersible dive in 2003, he spotted a huge sponge he nicknamed “Jabba the Hutt,” the large sluglike character from “Star Wars.” But it was a quarter to a third of the size of the newest find, he said.

Wagner, science lead of the expedition with NOAA’s Office of National Marine Sanctuaries, said the largest portion of the planet is found in deep waters, the vast majority of which has never been explored.

“Finding such an enormous and presumably old sponge emphasizes how much can be learned from studying deep and pristine environments such as those found in the remote Papahanaumokuakea Marine National Monument,” Wagner said in a news release.

The latest find also underscores the need to protect the area using the highest conservation measures available, according to the paper.