Meeting Abstract
Larvaceans (Class Appendicularia) are found throughout the world’s oceans and affect food webs across trophic levels via elaborate mucus feeding structures they create. Larvaceans swim tethered to their mucus houses, forcing seawater and particles through filters that eventually lead to their mouth. In Monterey Bay, giant larvaceans (Genus Bathochordaeus) can be found between 50 and 400 m, and can build mucus houses as large as 1 m across. While pumping fluid through their mucus houses, giant larvaceans are able to filter as much as 80 L/hr, consume and repackage microplastics, and contribute significantly to carbon cycling in the oceans due to their abandoned, sinking houses. Despite having such an important ecological role, little is known about the structure and function of giant larvacean houses. Using DeepPIV, an instrument that is mounted to a remotely operated vehicle (ROV) that is deployable from the sea surface to 4000 m, we can conduct quantitative in situ measurements of (1) fluid motion and (2) 3D reconstructions of mucus and gelatinous structures. During a deployment of DeepPIV in 2015, we observed a giant larvacean, Bathochordaeus stygius, building its house. In the 25+ year history of ROV observations in Monterey Bay, this behavior has only been partially observed one other time. With DeepPIV, we were able to observe changes in the mucus house over time, which reveals surprising arrangement of structures that have important implications to giant larvacean ecology.
