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/ Source: Live Science

They don't have gaping maws or fearsome talons. But don't be fooled. These sponges — though they look like fuzzy twigs — are killers.

Four new species of carnivorous sponges that prey on shrimplike amphipods and other small animals were discovered in deep waters off the Pacific coast of North America, scientists announced.

Most sponges are filter feeders. They use specialized cells called choanocytes, which have tiny, beating tails that help pull in bacteria and single-celled organisms from the surrounding water. But carnivorous sponges lack these water-moving cells. Instead, they've developed a different strategy to snare food.

A close-up view of Asbestopluma monticola, one of four new species of carnivorous sponges discovered off the West Coast of North America.(c) 2006 MBARI

"To keep beating the whiplike tails of the choanocytes takes a lot of energy," study author Lonny Lundsten, a biologist with the Monterey Bay Aquarium Research Institute, said in a statement. "And food is hard to come by in the deep sea. So these sponges trap larger, more nutrient-dense organisms, like crustaceans, using beautiful and intricate microscopic hooks."

Within a few hours, a carnivorous sponge will start digesting the prey in its clutches. Eventually, all that's left is an empty shell.

Lundsten and colleagues discovered four meat-eating sponges with the help of underwater remote-operated vehicles (ROVs) that video-recorded the sponges and plucked samples from the seafloor with a robotic arm.

One species, Asbestopluma monticola, was first collected in 2006 at the top of Davidson Seamount, an ancient underwater volcano off the coast of California. It was living among a community of corals, sponges and echinoderms (a family that includes starfish and sand dollars). The three other new species were all found in extreme chemosynthetic habitats with little light and sparse oxygen.

Scientists didn't discover meat-eating sponges until just 20 years ago. The new species join just seven other types of carnivorous sponges that have been found so far in the Northeast Pacific, including a bizarre species that looks like a harp.

- Megan Gannon, Live Science

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