Swimming hundreds of feet beneath the ocean’s surface in many parts of the world are prolific architects called giant larvaceans.
These zooplankton are not particularly giant themselves (they resemble tadpoles and are about the size of a pinkie finger), but every day, they construct one or more spacious houses” that can exceed three feet in length. The houses are transparent mucus structures that encase the creatures inside. Giant larvaceans beat their tails to pump seawater through these structures, which filter tiny bits of dead or drifting organic matter for the animals to eat. When their filters get clogged, the larvaceans abandon ship and construct a new house. Laden with debris from the water column, old houses rapidly sink to the seafloor.
In a study published in Science Advances on Wednesday, scientists near California’s Monterey Bay have found that, through this process, giant larvaceans can filter all of the bay’s water from about 300 to 1,000 feet deep in less than two weeks, making them the fastest known zooplankton filter feeders. In doing so, the creatures help transfer carbon that has been removed from the atmosphere by photosynthesizing organisms to the deep sea, where it can be buried and stored long term. And given their abundance in other parts of the world, these organisms likely play a crucial role in the global carbon cycle.