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ScienceShot: Carnivorous Candelabra of the Deep

With its vertical branches sticking up from the seafloor like a deep-sea candelabra, the harp sponge (Chondrocladia lyra) seems like something out of a Dr. Seuss book. But the newly described invertebrate isn't so benign. Rather than filtering the water for bacteria and other single-celled organisms like most sponges do, the harp sponge employs Velcro-like barbs on its vertical branches to snag tiny crustaceans called copepods as they swim past. Then, cells specialized for digesting prey surround the captured swimmer and slowly start to digest it. These multipurpose branches are also involved in reproduction: The tips of each branch end in knobs filled with packets of sperm that are released into the water when they mature. Once these packets contact another harp sponge, researchers suggest, they make their way along the branch until they find eggs to fertilize. Geologists, not marine biologists, were the first to spot the sponges; in 2000, the researchers were investigating the Gorda Ridge off the northern California coast using remotely operated vehicles run by the Monterey Bay Aquarium Research Institute in Moss Landing, California. There, they observed the sponges anchored via rootlike structures on 3300-meter-deep muddy plains.

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